w********2
发帖数: 632 | 1 gmo食品最大的问题是：有些（～0.1%）的基因片段进入人体内没被消化成单个的核酸
。这些dna序列有些就是植入的片段。一般来说植入片段突变比例都比普通dna序列高很
多，如果是transposon之类的，可以在genome内到处跑，导致很多基因失效，还会遗传
。所以这种潜在威胁谁也预测不了。
当年1930年代pesticide出来时也是一致叫好，结果1960年代就傻眼了。epa发展最鼎盛
时期是1960-1990，拜托pesticide。谁敢打包票说gmo食品不出现像pestcide一样的问
题？30年后monsanto的专利正好失效，中国等3类国逐渐掌握了相关技术，到时肯定会
出来很多gmo副作用的报告，有啥用，monsanto的股东钱赚够了，全世界一代人都被污
染了。欧洲本身知道这种玩的套路，所以干脆拖30年再说。 | w********2
发帖数: 632 | 2 Chinese researchers have found small pieces of rice ribonucleic acid (RNA)
in the blood and organs of humans who eat rice. The Nanjing University-based
team showed that this genetic material will bind to receptors in human
liver cells and influence the uptake of cholesterol from the blood.
The type of RNA in question is called microRNA (abbreviated to miRNA) due to
its small size. MiRNAs have been studied extensively since their discovery
ten years ago, and have been implicated as players in several human diseases
including cancer, Alzheimer's, and diabetes. They usually function by
turning down or shutting down certain genes. The Chinese research provides
the first in vivo example of ingested plant miRNA surviving digestion and
influencing human cell function in this way.
Should the research survive scientific scrutiny -- a serious hurdle -- it
could prove a game changer in many fields. It would mean that we're eating
not just vitamins, protein, and fuel, but gene regulators as well.
That knowledge could deepen our understanding of many fields, including
cross-species communication, co-evolution, and predator-prey relationships.
It could illuminate new mechanisms for some metabolic disorders and perhaps
explain how some herbal and modern medicines function.
This study had nothing to do with genetically modified (GM) food, but it
could have implications on that front. The work shows a pathway by which new
food products, such as GM foods, could influence human health in previously
unanticipated ways. | w********2
发帖数: 632 | | M*P
发帖数: 6456 | 4 牛逼。
：gmo食品最大的问题是：有些（～0.1%）的基因片段进入人体内没被消化成单个的核酸
：。这些dna序列有些就是植入的片段。一般来说植入片段突变比例都比普通dna序列高
很多，如果是transposon之类的，可以在genome内到处跑，导致很多基因失效，还会遗
传。所以这种潜在威胁谁也预测不了。 | d*****u
发帖数: 17243 | 5 但是不转基因的食物也有这个问题。
人是杂食动物，啥都吃。 | w********2
发帖数: 632 | 6 普通的dna片段不容易造成突变。genetic engineering专选容易突变的dna 或 rna，所
以有危险。
【在 d*****u 的大作中提到】
: 但是不转基因的食物也有这个问题。
: 人是杂食动物，啥都吃。
| d*****u
发帖数: 17243 | 7 不管是否转基因都有容易突变的片段。只不过转基因可以选择性的改变那些片段。
而且食物里的突变对人体的影响几乎就是白噪声。
【在 w********2 的大作中提到】
: 普通的dna片段不容易造成突变。genetic engineering专选容易突变的dna 或 rna，所
: 以有危险。
| w********2
发帖数: 632 | 8 不是的。如果有mi rna transposon promoter之类的完整进入人体内，就可能对基因表
达甚至genome本身起作用。它们和普通的食物中的基因片段是很不一样的。
【在 d*****u 的大作中提到】
: 不管是否转基因都有容易突变的片段。只不过转基因可以选择性的改变那些片段。
: 而且食物里的突变对人体的影响几乎就是白噪声。
| K*****2
发帖数: 9308 | | w********2
发帖数: 632 | 10 都是分子遗传学家从稀有细菌甚至病毒中找出来再优化，然后植入gmo植物的。绝大部
分人类基本一辈子没机会接触这些dna序列，也没任何免疫机制防备。
【在 w********2 的大作中提到】
: 不是的。如果有mi rna transposon promoter之类的完整进入人体内，就可能对基因表
: 达甚至genome本身起作用。它们和普通的食物中的基因片段是很不一样的。
| | | w********2
发帖数: 632 | 11 Horizontal gene transfer (HGT) is the stable transfer of genetic material
from one organism to another without reproduction or human intervention.
Transfer occurs by the passage of donor genetic material across cellular
boundaries, followed by heritable incorporation to the genome of the
recipient organism. In addition to conju- gation, transformation and
transduction, other diverse mechanisms of DNA and RNA uptake occur in nature
. The genome of almost every organism reveals the footprint of many ancient
HGT events. Most commonly, HGT involves the transmission of genes on viruses
or mobile genetic elements. HGT first became an issue of public concern in
the 1970s through the natural spread of antibiotic resistance genes amongst
pathogenic bacteria, and more recently with commercial production of
genetically modified (GM) crops. | w********2
发帖数: 632 | 12 The rapidly growing library of complete genome se- quences reveals that HGT
is a major factor in shaping the genomes of all organisms. Comparison of
three Es- cherichia coli strains reveals that only 39% of the genome is
conserved, and the rest differs, mainly as a consequence of HGT (Welch et al
., 2002). About 50% of the human genome is composed of mobile genetic
elements, which have largely originated through HGT at different times in
our evolutionary past, and undergone varying degrees of expansion through
gene duplication (International Hu- man Genome Sequencing Consortium, 2001). | w********2
发帖数: 632 | 13 The discovery of horizontal gene transfer (HGT) can be traced to 1928 when
Fred Griffith reported the trans- fer of genetic material from heat-killed
virulent Strep- tococcus pneumoniae to an avirulent form of the bac- terium
by a process he described as transformation (Bushman, 2002). It wasn’t
until 1946 that other forms of non-reproductive gene transfer between
organisms were identified and variously described as conjugation, trans-
duction, recombination, rearrangement, linkage disequi- librium, etc. (
Bushman, 2002). Since the 1980s these dif- ferent examples of gene transfer
have become known collectively as either horizontal or lateral gene transfer
(Gogarten et al., 2002; Koonin et al., 2001; Ochman et al., 2000; Syvanen,
1994). Both terms are used to describe gene exchange in nature that occurs
between organisms without recourse to reproduction. | w********2
发帖数: 632 | 14 In the short term, HGT can increase genetic diversity and promote the spread
of novel adaptations between organisms (Marri et al., 2007; Thomason and
Read, 2006). HGT has been a major contributory factor to the rapid spread of
antibiotic re- sistance amongst pathogenic bacteria in the last 50 years (
Mazel and Davies, 1999), and the emergence of in- creased virulence in
bacteria, eukaryotes and viruses (Derbise et al., 2007; Friesen et al., 2006
; Mild et al., 2007). In the long term it has been proposed that HGT has
contributed to the major transitions in evolution (Koonin, 2007). | w********2
发帖数: 632 | 15 Gene transfer refers to the movement of genes within or between individual
organisms. HGT is often used to refer to all forms of gene transfer that do
not involve parent- to-offspring transfer (sexual or asexual). It can occur
ei- ther naturally or by human intervention (e.g. gene tech- nology, embryo
rescue, in vitro fertilization, protoplast fusion, self-cloning). In some
cases, HGT may be tran- sient, and not perpetuated in the offspring. Each
form of HGT comes with different considerations of risk, which in the case
of genetic modification (genetic engineering) is commonly regulated through
legislation. In this review, the focus is on HGT that is perpetuated in the
offspring. | w********2
发帖数: 632 | 16 There are several approaches to identify genetic changes due to HGT,
including:
(1) experimental evidence, whereby a genetic marker is monitored for gene
transfer to a recipient organism;
(2) phylogenetic analysis of gene sequences to identify topological
inconsistencies between different gene families;
(3) nucleotide compositional analysis to identify any gene that has a
nucleotide pattern that differs signifi- cantly from the overall genome; and
(4) evolutionary scenarios to explain the patchy appear- ance of a genetic
signature, sequence or function that is not shared by close relatives. | w********2
发帖数: 632 | 17 Experimental evidence
Many laboratory studies of bacterial conjugation, trans- duction and
transformation over the last 80 years have provided valuable insights into
some of the mechanisms and frequencies of HGT. More recently, field studies
on HGT support many of the laboratory findings (Souza et al., 2002) and
reveal the widespread occurrence of HGT amongst bacteria and viruses (Maeda
et al., 2006; Sander and Schmieger, 2001; van den Eede et al., 2004;
Weinbauer, 2004).
HGT has been recorded in a number of environ- mental situations such as soil
, seawater, freshwater, an- imal and industrial waste products, plant
surfaces, animal intestines, human saliva and food products (Bushman, 2002;
Davison, 1999; Lilley et al., 2003; van den Eede et al., 2004; Wolska, 2003)
. Some settings, such as bac- terial biofilms, reveal highly efficient HGT (
Molin and Tolker-Nielsen, 2003; van Elsas et al., 2003; Wuertz et al., 2004)
, whereas the simplified conditions in labo- ratory studies probably lack
many of the appropriate bi- otic and abiotic signals that facilitate HGT in
nature (Mel and Mekalanos, 1996; Nielsen and van Elsas, 2001). For example,
the presence of algae stimulates the release of bacterial plasmid DNA that
is suitable for HGT (Matsui et al., 2003) and chitin induces natural
competence in Vibrio cholerae (Meibom et al., 2005).
Nevertheless, the number of HGT events is generally many orders of magnitude
lower relative to gene transfer by reproduction (Babic ́ et al., 2008)
. Consequently, ex- perimental screening for HGT has relied on testing organ
- isms such as bacteria and viruses that can be cultivated in vast numbers
and have short generation times. In addi- tion, powerful selection methods
such as the use of antibi- otics have been used to identify rare transfer
events. More recently, other markers like the green fluorescent protein have
been shown to allow monitoring of individual oc- currences of HGT and
provide accurate measures of their frequency (Babic ́ et al., 2008;
Perumbakkam et al., 2006; Sørensen et al., 2005). In some cases, the
transforma- tion frequencies determined from these studies are much greater
than cultivation-based selection systems (Rizzi et al., 2008). | c******g
发帖数: 269 | 18 又是一个什么都吃，吃的里面可能有毒药，所以吃毒药没关系。弱智不是病，是残疾，
不歧视你。
[在 daigaku (๑۩۞۩๑) 的大作中提到：]
:但是不转基因的食物也有这个问题。
:人是杂食动物，啥都吃。 | w********2
发帖数: 632 | 19 Phylogenetic analysis
Phylogenetic analysis of gene or protein sequences for the presence of an
incongruent phylogenetic signal is considered to represent the most rigorous
method for de- tecting past HGT events (Koonin et al., 2001; Syvanen, 1994)
. Smith et al. (1992) established the basic require- ments for application
of the phylogenetic congruency test to identify and support cases of HGT.
The test com- pares the phylogenetic tree constructed from a specific
protein or gene sequence with the known phylogeny for the species. Therefore
, if a bacterial gene groups with homologs from a particular eukaryotic
lineage and only distantly with homologs from other bacteria, then HGT seems
likely.
However, the construction of unambiguous trees is time-consuming and
susceptible to a number of confounding factors such as gene loss,
insufficient phy- logenetic signal, rapid nucleotide changes in some lin-
eages, strongly biased nucleotide composition, poor se- quence alignments,
inadequate algorithms, evolution not following the most parsimonious path,
saturation where multiple changes can lead to revertants, long branch at-
traction, insufficient gene sampling, inclusion of paralogs and uncertain
species tree (Koonin et al., 2001; Lebrun et al., 2006). | w********2
发帖数: 632 | 20 Anomalous nucleotide composition
HGT inferred from anomalous nucleotide composition is based on the premise
that genomes evolve to species- specific values due to replication,
transcription and trans- lation biases, variations in nucleotide and amino
acid pools, and different DNA repair preferences. Thus, if codon usage, GC
content or oligonucleotide signatures differ significantly from the mean for
a given genome, then HGT may be invoked (Dufraigne et al., 2005; Hooper and
Berg, 2002; Kanaya et al., 2001; Karlin et al., 1998; Lawrence and Ochman,
1998; Sandberg et al., 2001; Tsirigos and Rigoutsos, 2005). A significant
fraction of many prokaryote genomes, up to 20%, has been classified as
recent HGTs according to these criteria (Garcia-Vallve et al., 2003).
The advantage of detecting HGT by anomalous nu- cleotide composition is that
it requires only a single genome to examine and is very rapid to assess.
However, it usually detects more recent changes and requires the genome of
the donor organism to be distinctive relative to the recipient genome. In
addition, some native genes may also show atypical patterns due to chance,
gene-specific selection pressure or some higher-order structural con-
straints on chromosome structure (Koski et al., 2001). | | | w********2
发帖数: 632 | 21 Inconsistent evolutionary scenarios
Deriving a parsimonious evolutionary scenario is based on the premise that
over time, genetic change is relent- less, such that distant relatives are
expected to have fewer features in common than close relatives (Koonin et al
., 2001). Therefore, the presence of some distinguishing ge- netic signal in
a distant relative but absent from more closely related organisms
contradicts this expectation. The most common causes of these anomalies are
loss of the genetic signal in close relatives or gene acquisition in a
distant relative.
In practice, genomes provide a wealth of data that can be used as a source
of distinctive features that have re- vealed unexpected relationships
indicative of HGT. Some of these features include biochemical/biological
prop- erties (Pierce et al., 2003; Wenzl et al., 2005), recom- bination
signals in closely related organisms (Escobar- Páramo et al., 2004;
Hakenbeck et al., 2001), presence of mobile genetic elements (MGEs) or viral
sequences (Burrus and Waldor, 2004; Paulsen et al., 2003; Welchet al., 2002
), gene content pattern (Hall et al., 2005; Hao and Golding, 2004; Homma et
al., 2007; Hong et al., 2004; Korbel et al., 2002), presence/absence of
genomic features (Gupta and Griffiths, 2002; Kroll et al., 1998; Snyder et
al., 2007), database searches for nearest rela- tives (Aravind et al., 1998;
Parkinson and Blaxter, 2003; Ragan and Charlebois, 2002) and unequal rates
of genetic divergence (Bromham and Penny, 2003; Novichkov et al., 2004).
Typically, all of these methods for detecting HGT uncover different sets of
genes (Ragan, 2001) and may miss true HGT events (false negatives) and incor
- rectly identify other putative HGT events (false posi- tives) (Canbä
ck et al., 2004; Daubin and Ochman, 2004; Daubin and Perrière, 2003;
Gogarten and Olendzenski, 1999; Guindon and Perrière, 2001; Koski and
Golding, 2001; Koski et al., 2001; Mira et al., 2002). Differ- ent methods
can also detect HGT of different relative ages (Ragan et al., 2006).
Therefore, a combination of approaches may be necessary to identify and
confirm HGT (Eisen, 2000; Lawrence and Ochman, 2002; Ragan, 2001).
In addition, HGT can be difficult to distinguish from other forms of gene
transfer. For example, the large scale intra-genomic transfer of genes from
the chloro- plast or mitochondrion to the nucleus (Martin, 2003) can
confound the detection of bacterium-to-eukaryote transfers by HGT. Also,
false diagnosis of gene absence (Zhaxybayeva et al., 2007) or experimental
errors, such as contamination of DNA samples, may give misleading
indications of HGT (DeMarco et al., 2007). | w********2
发帖数: 632 | 22 PATHWAYS FOR HORIZONTAL GENE TRANSFER
HGT can occur between closely related, but also dis- tantly related
organisms such as viruses and animals (Filée et al., 2002; Hughes and
Friedman, 2003) or plants and bacteria (Aoki and Syo ̄no, 1999;
Intrieri and Buiatti, 2001; Koonin et al., 2001; White et al., 1983).
An overview of the major pathways for HGT between donor and recipient is
depicted in Figure 1. The relative impact of each pathway also indicates
that MGEs are one of the most important conduits for HGT between organ- isms
(van Elsas and Bailey, 2002; Zaneveld et al., 2008). | w********2
发帖数: 632 | 23 Mobile genetic elements
MGEs are non-essential (accessory) genomic elements composed of genes and
structural features that facil- itate their spread both within and between
organisms (Doolittle and Sapienza, 1980; Orgel and Crick, 1980). They are
found in the genomes of all prokaryotes and eukaryotes. MGEs share many
features and often share a common ancestry with viruses. The main difference
is that viruses are usually capable of extracellular persis- tence.
MGEs, including defective forms, are a dominant feature of most genomes.
MGEs constitute 35% of the genome of E. coli strain CFT073 (Welch et al.,
2002), about 50% of the human genome (International Human Genome Sequencing
Consortium, 2001) and about 80% of the maize genome (Whitelaw et al., 2003).
Major types of MGE include DNA transposons, retro- transposons, plasmids,
composite mobile elements such as conjugative transposons, genomic islands,
pathogenic- ity islands, integrative conjugative plasmids, mobilis- able
transposons (Burrus and Waldor, 2004; Osborn and Böltner, 2002), mobile
introns/inteins (Lambowitz and Zimmerly, 2004; Poulter et al., 2007;
Yamanaka et al., 2002) and non-autonomous mobile elements that lack encoded
enzymes or suitable recognition sequences necessary for mobility. For
example, the miniature inverted-repeat transposable elements (MITE,
Feschotte et al., 2002), short interspersed nuclear elements (SINE, Moran
and Gilbert, 2002) and processed pseudogenes (Kazazian, 2004) all lack a
recombinase or reverse transcriptase gene necessary for independent mobil-
ity. Other important groups of non-autonomous self- ish elements include
restriction-modification systems (Kobayashi, 2001) and integrons. The basic
integron structure consists of an integrase gene and an out- ward facing
promoter, which together act as an efficient gene capture/gene expression
system in bacteria (Michael et al., 2004). When associated with autonomous
MGEs, integrons provide an important mechanism for HGT of genes for
antibiotic resistance, pathogenicity and other adaptive functions (Boucher
et al., 2007; Carattoli, 2001; Ochman et al., 2000; Rowe-Magnus and Mazel,
2001). | w********2
发帖数: 632 | 24 MGEs are drivers of genomic and biological diversity (Böhne et al.,
2008) and play a significant role in HGT in several ways:
(1) MGEshaveevolvedmechanismsthatenhancethepo- tential for gene transfer
between organisms. For ex- ample, conjugative elements have evolved highly
ef- ficient mechanisms for the passage of genes into a recipient cell.
(2) MGEs can alter the function of genes in the vicin- ity of the insertion
in the host genome. These alter- ations can include disruption or
inactivation of genes at the site of insertion. Conversely, insertional muta
- genesis by an MGE can also result in benefits to the host such as
provision of regulatory sequences, re- pair of double-stranded DNA breaks,
telomere main- tenance in Drosophila, foetal implantation in mam- mals, or
genome restructuring and speciation (Jordan et al., 2003; McClure, 2000;
Peaston et al., 2004).
(3) MGEs contribute novel structural and functional ge- netic material that
is often further spread throughout the genome (Touchon and Rocha, 2007), and
in some cases may promote further horizontal dissemination of genes (Beaber
et al., 2004).
(4) HGT of MGEs can result in the transfer of addi- tional genes through
genetic piggy-backing. For ex- ample, MGEs are the primary vehicle for the
spread of antibiotic-resistance genes, pathogenicity determi- nants and
biodegradation pathways amongst bacteria (de la Cruz and Davies, 2000). | w********2
发帖数: 632 | 25 HGT involving prokaryotes
Many studies support the significant role of HGT in the evolution of
prokaryotes (Gogarten et al., 2002; Jain et al., 2003; Kunin and Ouzounis,
2003). The principle sources of novel genes are provided by other prokary-
otes, viruses and MGEs (Fig. 1). In particular, plasmids and composite
mobile elements contribute significantly to HGT between prokaryotes. In some
cases, composite elements and megaplasmids are composed of more than 100
genes (Bentley et al., 2002; Hacker et al., 1997), and account for much of
the genomic variation between bac- terial strains of the same species (Welch
et al., 2002). In contrast, DNA transposases, retrotransposons and mobile
introns/inteins carry few genes, and are primarily associ- ated with intra-
genomic gene movement.
Viruses contribute to prokaryotic genomes, both di- rectly, in the form of
viral (prophage) insertions (typ- ically 1–10 copies) that are found in
most bacterial genomes, and indirectly, through packaging additional
cellular genes during the infection cycle. Prokaryote genomes also contain
many ORFs with no dectectable homology to other ORFs in the databases. Some
of these are postulated to have been obtained from viruses (Daubin and
Ochman, 2004; Yin and Fischer, 2006).
More surprisingly is the apparent rarity of eukary- otic genes in
prokaryotic genomes (Andersson, 2005; Guljamow et al., 2007; Pilhofer et al.
, 2007; Rogers et al., 2007). The abundant opportunities for prokaryotes to
en- counter eukaryotic genetic material suggest that signifi- cant
functional (e.g. the presence of introns in eukaryotic genes, inefficient
gene transfer mechanisms) and selec- tive barriers have restricted the long-
term acquisition of eukaryotic genes by bacteria.
One minor pathway for HGT to prokaryotes is the di- rect uptake of
extracellular DNA. Natural genetic trans- formation is a feature of many
bacteria. Although cell ly- sis of any organism can contribute to this
extracellular DNA pool, several studies suggest that secretion of DNA from
living bacteria may also be an important source of genetic material (Draghi
and Turner, 2006; Vlassov et al., 2007). | C**********e
发帖数: 23303 | 26 说得很对
所以中国更要加紧研究
这是基因武器的基础
未来大杀器 | w********2
发帖数: 632 | 27 大国都知道这个，经济学人刚出来了一篇讲gene drive，就是谈基因武器的可能性。
小八路回国说不定就被软禁，以后真的成为钱八路了。LOL
【在 C**********e 的大作中提到】
: 说得很对
: 所以中国更要加紧研究
: 这是基因武器的基础
: 未来大杀器
| w********2
发帖数: 632 | 28 你这中宣部高级特工赶紧退党吧，未来还有更大的杀气等着党员们呢。
【在 C**********e 的大作中提到】
: 说得很对
: 所以中国更要加紧研究
: 这是基因武器的基础
: 未来大杀器
| w********2
发帖数: 632 | 29 HGT involving viruses
Viruses undergo frequent HGT but this is typically re- stricted to gene
exchange between viral genomes present in the same infection. Many viral
genomes have few genes (less than 10), which constrains the number and types
of genes that can be expected to increase or even maintain fitness.
Consequently, viruses with small genomes have been rarely reported to
contain non- virally derived genetic elements (Agranovsky et al., 1991;
Becker, 2000; Khatchikian et al., 1989; Masuta et al., 1992; Mayo and Jolly,
1991; Meyers et al., 1991).
The genomes of viruses with large DNA genomes show more examples of host
gene acquisitions by HGT (Fu et al., 2008; Hughes and Friedman, 2003; Raoult
et al., 2004). However, the repertoire of host genes present in the viral
genome is restricted to relatively few gene types. In addition, many viral
genes appear to closely follow the evolution of the host, such as the
thymidine kinase gene of poxviruses (Boyle et al., 1987). HGT events that
result in the acquisition of genes from distantly-related species are
relatively infrequent and are more likely to have occurred over evolutionary
time scales that reflect millions of years (Gibbs, 1987). | C**********e
发帖数: 23303 | 30 所以说
哥是大力支持中国也要加强研究的
: 大国都知道这个，经济学人刚出来了一篇讲gene drive，就是谈基因武器的可能
性。
: 小八路回国说不定就被软禁，以后真的成为钱八路了。LOL
【在 w********2 的大作中提到】
: HGT involving viruses
: Viruses undergo frequent HGT but this is typically re- stricted to gene
: exchange between viral genomes present in the same infection. Many viral
: genomes have few genes (less than 10), which constrains the number and types
: of genes that can be expected to increase or even maintain fitness.
: Consequently, viruses with small genomes have been rarely reported to
: contain non- virally derived genetic elements (Agranovsky et al., 1991;
: Becker, 2000; Khatchikian et al., 1989; Masuta et al., 1992; Mayo and Jolly,
: 1991; Meyers et al., 1991).
: The genomes of viruses with large DNA genomes show more examples of host
| | | w********2
发帖数: 632 | 31 你赶紧退党吧，说不定有个针对中共党员的gene drive很快会出来了。lol
【在 C**********e 的大作中提到】
: 所以说
: 哥是大力支持中国也要加强研究的
:
:
: 大国都知道这个，经济学人刚出来了一篇讲gene drive，就是谈基因武器的可能
: 性。
:
: 小八路回国说不定就被软禁，以后真的成为钱八路了。LOL
:
| C**********e
发帖数: 23303 | 32 这种基因灭绝武器
只要是黄种人都不能幸免
美华也躲不开的
所幸运的是听说中国也在研发针对白人基因的同类武器
那就无所谓了
: 你赶紧退党吧，说不定有个针对中共党员的gene drive很快会出来了。lol
【在 w********2 的大作中提到】
: 你赶紧退党吧，说不定有个针对中共党员的gene drive很快会出来了。lol
| d*****u
发帖数: 17243 | 33 智商素质双低的蠢驴
讨论基因片段的摄入和吃毒药有个屁的关系
【在 c******g 的大作中提到】
: 又是一个什么都吃，吃的里面可能有毒药，所以吃毒药没关系。弱智不是病，是残疾，
: 不歧视你。
: [在 daigaku (๑۩۞۩๑) 的大作中提到：]
: :但是不转基因的食物也有这个问题。
: :人是杂食动物，啥都吃。
| w********2
发帖数: 632 | 34 你想拉普通中国人垫背还真不行。这次的灭党gene drive专门清除中共假恶斗基因，嘿
嘿，你不退党跑不了。不信你就看看，一种强大的疾病很快会来消灭中共党员。话搁着
这儿。
【在 C**********e 的大作中提到】
: 这种基因灭绝武器
: 只要是黄种人都不能幸免
: 美华也躲不开的
: 所幸运的是听说中国也在研发针对白人基因的同类武器
: 那就无所谓了
:
:
: 你赶紧退党吧，说不定有个针对中共党员的gene drive很快会出来了。lol
:
| C**********e
发帖数: 23303 | 35 哈哈哈
前面还靠谱 后面就扯淡了
难道你真是轮子？
原子弹下无冤魂
: 你想拉普通中国人垫背还真不行。这次的灭党gene drive专门清除中共假
恶斗基
因，嘿
: 嘿，你不退党跑不了。不信你就看看，一种强大的疾病很快会来消灭中共
党员。
话搁着
: 这儿。
【在 w********2 的大作中提到】
: 你想拉普通中国人垫背还真不行。这次的灭党gene drive专门清除中共假恶斗基因，嘿
: 嘿，你不退党跑不了。不信你就看看，一种强大的疾病很快会来消灭中共党员。话搁着
: 这儿。
| w********2
发帖数: 632 | 36 gene drive比热核武器精确的多，可以消灭你一个家族而不影响任何别人。就这么精确。
【在 C**********e 的大作中提到】
: 哈哈哈
: 前面还靠谱 后面就扯淡了
: 难道你真是轮子？
: 原子弹下无冤魂
:
:
: 你想拉普通中国人垫背还真不行。这次的灭党gene drive专门清除中共假
: 恶斗基
: 因，嘿
:
: 嘿，你不退党跑不了。不信你就看看，一种强大的疾病很快会来消灭中共
: 党员。
| C**********e
发帖数: 23303 | 37 是的
确实精确厉害
所以中国才大力研究搞平衡
: gene drive比热核武器精确的多，可以消灭你一个家族而不影响任何别人。就这
么精确。
【在 w********2 的大作中提到】
: gene drive比热核武器精确的多，可以消灭你一个家族而不影响任何别人。就这么精确。
| w********2
发帖数: 632 | 38 你这么多年为中共站台造了不少孽，赶紧退党还有希望，一旦出事，后悔也来不及了，
连你的家族后人都会一起还孽债。中共党员的基因都是有记号的，把这种snp作为gene
drive的启动因子，你和你的家族就玩完了。
【在 C**********e 的大作中提到】
: 是的
: 确实精确厉害
: 所以中国才大力研究搞平衡
:
:
: gene drive比热核武器精确的多，可以消灭你一个家族而不影响任何别人。就这
: 么精确。
:
| C**********e
发帖数: 23303 | 39 刚大学时因为被人举报生活作风问题没入成共党
但是确实支持中共活摘轮子下水废物利用
扫除汉奸老将
你叫嚣也没用 法力在哪里呢？
: 你这么多年为中共站台造了不少孽，赶紧退党还有希望，一旦出事，后悔也来不
及了，
: 连你的家族后人都会一起还孽债。中共党员的基因都是有记号的，把这种snp作
为gene
: drive的启动因子，你和你的家族就玩完了。
【在 w********2 的大作中提到】
: 你这么多年为中共站台造了不少孽，赶紧退党还有希望，一旦出事，后悔也来不及了，
: 连你的家族后人都会一起还孽债。中共党员的基因都是有记号的，把这种snp作为gene
: drive的启动因子，你和你的家族就玩完了。
| w********2
发帖数: 632 | 40 像你这种认同活摘人体的人渣，genome肯定有记号，等着被gene drive消灭吧。
【在 C**********e 的大作中提到】
: 刚大学时因为被人举报生活作风问题没入成共党
: 但是确实支持中共活摘轮子下水废物利用
: 扫除汉奸老将
: 你叫嚣也没用 法力在哪里呢？
:
:
: 你这么多年为中共站台造了不少孽，赶紧退党还有希望，一旦出事，后悔也来不
: 及了，
:
: 连你的家族后人都会一起还孽债。中共党员的基因都是有记号的，把这种snp作
: 为gene
:
: drive的启动因子，你和你的家族就玩完了。
| | | C**********e
发帖数: 23303 | 41 哥等着哈
你是不是也承认轮子没有法力啦？
否则还等个屁？
: 像你这种认同活摘人体的人渣，genome肯定有记号，等着被gene drive消灭吧。
【在 w********2 的大作中提到】
: 像你这种认同活摘人体的人渣，genome肯定有记号，等着被gene drive消灭吧。
| w********2
发帖数: 632 | 42 陈毅说的那句记得吧：不是不报，时候未到。别高兴的太早了，等着见棺材吧。
【在 C**********e 的大作中提到】
: 哥等着哈
: 你是不是也承认轮子没有法力啦？
: 否则还等个屁？
:
:
: 像你这种认同活摘人体的人渣，genome肯定有记号，等着被gene drive消灭吧。
:
| C**********e
发帖数: 23303 | 43 是的
被活摘的轮子都是遭报应了吗？说不通啊？
: 陈毅说的那句记得吧：不是不报，时候未到。别高兴的太早了，等着见棺材吧。
【在 w********2 的大作中提到】
: 陈毅说的那句记得吧：不是不报，时候未到。别高兴的太早了，等着见棺材吧。
| I********x
发帖数: 858 | 44 尼玛的千老,几年前小崔反转的时候一堆老将千在菌斑讲科学，讲得是天花乱坠，信誓
旦旦好像不吃转基因就对不起科学。现在又转过头来讲科学，谁他妈吃转基因就是傻逼？
：都是分子遗传学家从稀有细菌甚至病毒中找出来再优化，然后植入gmo植物的。绝大部
：分人类基本一辈子没机会接触这些dna序列，也没任何免疫机制防备。 | w********2
发帖数: 632 | 45 哥当时不在场，不然就翻桌子了。这gmo食品一开始就争议很大。不是现在才有。
逼？
大部
【在 I********x 的大作中提到】
: 尼玛的千老,几年前小崔反转的时候一堆老将千在菌斑讲科学，讲得是天花乱坠，信誓
: 旦旦好像不吃转基因就对不起科学。现在又转过头来讲科学，谁他妈吃转基因就是傻逼？
:
: ：都是分子遗传学家从稀有细菌甚至病毒中找出来再优化，然后植入gmo植物的。绝大部
: ：分人类基本一辈子没机会接触这些dna序列，也没任何免疫机制防备。
| w********2
发帖数: 632 | 46 你现在嘴硬，以后有哭的时候，等着看自己家族为你的行为顶罪吧。
【在 C**********e 的大作中提到】
: 是的
: 被活摘的轮子都是遭报应了吗？说不通啊？
:
:
: 陈毅说的那句记得吧：不是不报，时候未到。别高兴的太早了，等着见棺材吧。
:
| w********2
发帖数: 632 | 47 HGT involving eukaryotes
The best recognized examples of HGT in eukaryotes in- clude the wholesale
absorption of bacterial genomes that once existed as endosymbionts or
parasites and now ex- ist as remnant genomes, such as mitochondria and plas-
tids (Gray, 1993). This process of ‘you are what you eat’ (Doolittle,
1998) has continued throughout evolu- tion and includes gene acquisitions
from both prokary- otic (Hotopp et al., 2007) and eukaryotic endosymbionts (
Li et al., 2006; Nosenko and Bhattacharya, 2007). For example, the
nucleomorph organelle of Guillardia theta was originally an absorbed algal
cell and is now a ves- tigal nucleus that contributes 302 genes to the host
genome, including genes necessary for photosynthesis (Douglas et al., 2001).
Cellular takeover of an endosym- biont genome may proceed over long
evolutionary time periods, and some examples may be in the early phase of
genetic piracy (Johnson et al., 2007). Bacterial para- sites have also
contributed to eukaryote evolution (Suzuki et al., 2002).
HGT involving gene transfers to eukaryotes has been more controversial (
Doolittle et al., 1990; Kurland et al., 2003; Syvanen, 1994). Nevertheless,
fungi and unicellu- lar eukaryotes appear to have participated in many gene
exchanges with bacteria (Andersson et al., 2007; Huang et al., 2004;
Rosewich and Kistler, 2000). The full se- quencing of eukaryotic genomes is
likely to considerably add to the knowledge of past HGT events. For example,
one group of metazoans, bdelloid rotifers, appear to be subject to far
greater HGT than is typical of most other multicellular organisms (Gladyshev
et al., 2008). | c******g
发帖数: 269 | 48 你认错人了，老子不是你爹那条智商素质双低的蠢驴，你看不懂这个analogy，因为你
遗传了吃转基因吃坏脑子的那条蠢驴的基因。
[在 daigaku (๑۩۞۩๑) 的大作中提到：]
:智商素质双低的蠢驴
:讨论基因片段的摄入和吃毒药有个屁的关系 | w********2
发帖数: 632 | 49 Indirect HGT
In addition to direct HGT between organisms as de- picted in Figure 1, forms
of indirect HGT have been observed, which involve an additional
intermediary or- ganism in gene transfer from a host organism to the final
recipient organism. The most notable are virus- mediated gene transfer (
transduction) between bacteria (Weinbauer, 2004), retrotransfer of a plasmid
to a sec- ond bacterium, acquiring host genes and returning to the original
bacterium (Ronchel et al., 2000), the spread of donor genetic material
between several different bacte- ria coexisting in complex communities or
biofilms (Molin and Tolker-Nielsen, 2003; van Elsas et al., 2003; Wuertz et
al., 2004); or from virus to virus via sequences inte- grated into a common
host organism. | w********2
发帖数: 632 | 50 MECHANISMS OF HORIZONTAL GENE TRANSFER
HGT is a two-step process with mechanistically and bio- chemically distinct
phases. Firstly, there is passage of donor genetic material across the cell
membrane(s) of the recipient cell, including other envelope structures such
as a cell wall or nuclear membrane. Secondly, there is sta- ble
incorporation of the donor genetic material into the genome of the recipient
organism such that the new gene may be perpetuated through the offspring.
In the case of multicellular organisms this involves gene transfer to germ
line cells, which are both fewer and less accessible than somatic cells in
most animals and plants. Each HGT event may be accompanied by expression of
the donor genetic material or changes to expression of endogenous genes in
the recipient organism. | | | w********2
发帖数: 632 | 51 Translocation of genetic material
The major mechanisms of HGT described in the literature include conjugation,
cellular competency (natural trans- formation) and virus-mediated
transduction (Chen et al., 2005; Dreiseikelmann, 1994; Dubnau, 1999).
However, these mechanisms only refer to the first step of any suc- cessful
gene transfer event, namely the passage of ge- netic material across
cellular barriers. Independent mech- anisms are involved in integrating the
new genes into the genome of the recipient organism.
Conjugation – Bacterial conjugation systems belong to a subfamily of type
IV secretory pathways that medi- ate the transport of DNA, proteins and
toxins across the cell envelope of bacterial, plant or animal cells (
Cascales and Christie, 2004; Ding et al., 2003; Gomis-Rüth et al., 2004).
Conjugation is widespread throughout bac- teria and is the most important
mechanism for translo- cating DNA between bacteria (Espinosa-Urgel, 2004;
Grohmann et al., 2003). In the natural environment conju- gation occurs
primarily between closely-related strains or species. However, it can occur
between distantly-related species, even between members of different domains
of the prokaryotes, the Archaea and Bacteria (Koonin et al., 2001).
The conjugation machinery is also used by the bac- terial phytopathogen
Agrobacterium to insert DNA into plant cells as part of the infection
process. DNA transfer from Agrobacterium to its host has been co-opted by
gene technology to introduce genes into plants and has been studied in
considerable detail (Gelvin, 2003; Tzfira et al., 2004; Zupan et al., 2000).
This mechanism of translo- cating genetic material across the eukaryotic
membrane has been experimentally adapted to introduce genes into yeast (
Bundock et al., 1995; Piers et al., 1996), filamen- tous fungi (de Groot et
al., 1998) and mammalian cells (Kunik et al., 2001). Other types of bacteria
have also been modified to transfer genes to yeast or plants by the same
mechanism (Broothaerts et al., 2005; Heinemann and Sprague, 1989). | w********2
发帖数: 632 | 52 Cellular competency (natural transformation) refers to the active uptake of
free (extracellular) DNA across the cell wall and cell membrane(s) using
cellular machinery designed to facilitate the process (Dubnau, 1999; Lorenz
and Wackernagel, 1994). It is a highly regulated physio- logical state that
is often sensitive to environmental cues (Molin and Tolker-Nielsen, 2003).
When the DNA is her- itably incorporated into the recipient’s genome, the
pro- cess is known as transformation.
Bacterial competency has been closely studied in many systems and is
associated with three steps, (1) re- lease of DNA into the environment, (2)
binding to spe- cific sites on the bacterial cell surface, and (3) transport
across the cell membrane through a specific pore, cou- pled to degradation
of one of the DNA strands. Many of the competency genes are related to those
of the type IV secretory pathway used in conjugation (Dubnau, 1999).
Although DNA uptake by competent cells has been observed for many bacteria (
Lorenz and Wackernagel, 1994), equivalent processes may occur with
eukaryotic cells. There is a growing number of reports of sponta- neous DNA
uptake by eukaryotes, such as DNA from human erythrocytes by malaria
parasites (Deitsch et al., 2001). However, it has not yet been established
that eu- karyotes have specialized systems equivalent to bacterial
competency genes for transporting DNA across the cell membrane.
Transduction – Viruses are able to package genes from the genome of one
bacterial host within their cap- sids and transfer these donor genes to a
second bacte- rial cell. Generalized transduction involves the transport of
any bacterial gene, whereas specialized transduction transports only
selected genes that are close to the attach- ment site where the virus was
integrated in the host bac- terial genome.
Marine environments are a major setting for virus-mediated gene transfer
between bacteria, where there is an estimated abundance of greater than 1029
virus particles (Hendrix et al., 1999; Weinbauer and Rassoulzadegan, 2004).
For example, virus-mediated gene transfer frequencies of around 10−8
have been re- ported from the Tampa Bay estuary, corresponding to around 3.6
× 1011 HGT events each day in the estuary (Jiang and Paul, 1998).
In addition to conjugation, transformation and trans- duction, other less
well recognised mechanisms of DNA uptake occur in nature, while other
mechanisms of HGT are probably yet to be elucidated, in particular, DNA up-
take by eukaryotes:
– Vesicle-mediated translocation by a range of Gram- negative bacteria such
as Neisseria gonorrheae, E. coli and Pseudomonas aeruginosa, which can bud
off vesicle structures that contain genetic material (e.g. antibiotic
resistance and virulence genes) and then fuse with another bacterium (
Dorward et al., 1989; Kadurugamuwa and Beveridge, 1997; Yaron et al., 2000).
– Virus-likeparticles(genetransferagent)formedfrom proteins encoded by some
bacterial genomes, which can trap random fragments of the genome (about
4400–13 600 base pairs) and transmit them to a sec- ond bacterium (
Dykhuizen and Baranton, 2001; Lang and Beatty, 2001; Marrs, 1974).
– Cellular fusion (fusion between cell membranes) that allows mixing of
entire genomes, can occur with some fungi, multicellular bacteria and
between membrane-bound viruses and their host (Hijri and Sanders, 2005;
Knipe and Howley, 2001).
– Phagocytosis/endocytosis, by which certain unicellu- lar eukaryotes (e.g.
amoeba) engulf entire cells that may be prokaryotic or eukaryotic (
Doolittle, 1998).
– Lysis of intracellular pathogens/endosymbionts has been shown to deliver
DNA into mammalian cells (Grillot-Courvalin et al., 2002).
– Cellular channels may account for some HGT events between parasitic
plants and their host (Haupt et al., 2001; Mower et al., 2004); this is
commonly used by plant viruses, which encode a movement protein that
modifies the plasmodesmata, allowing spread of virus between cells in a
plant (Hofmann et al., 2007).
– Vector-mediated translocation has been postulated as a mechanism for the
indirect transport of genes between eukaryotes, such as gene transfer
between Drosophila species by mites that feed on the eggs (Houck et al.,
1991) or via other biological vectors such as pollen, fungi, bacteria and
nematodes.
– Adventitious uptake of genetic material can occur when the cell membrane
is accidentally breached, whether mechanically, chemically or electrically,
such as in the entry by viruses after physical damage of a plant or animal
cell (Bos, 1999), by lightning in a manner analogous to genetic modification
by elec- troporation (Demanèche et al., 2001) or desiccation (Gladyshev et
al., 2008). |
|
