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61.
In spite of the increasing application of DNA fingerprinting to natural
populations and to the genetic identification of humans, explicit methods
for estimation of basic population genetic parameters from DNA
fingerprinting data have not been developed. Contributing to this omission
is the inability to determine, for multilocus fingerprinting probes,
relatively important genetic information, such as the number of loci, the
number of alleles, and the distribution of these alleles into specific
loci. One of the most useful genetic parameters that could be derived from
such data would be the average heterozygosity, which has traditionally been
employed to measure the level of genetic variation within populations and
to compare genetic variation among different loci. We derive here explicit
formulas for both the estimation of average heterozygosity at multiple
hypervariable loci and a maximum value for this estimate. These estimates
are based upon the DNA restriction-pattern matrices that are typical for
fingerprinting studies of humans and natural populations. For several
empirical data sets from our laboratory, estimates of average and maximal
heterozygosity are shown to be relatively close to each other. Furthermore,
variances of these statistics based on simulation studies are relatively
small. These observations, as well as consideration of the effect of
missing alleles and alternate numbers of loci, suggest that the average
heterozygosity can be accurately estimated using phenotypic DNA fingerprint
patterns, because this parameter is relatively insensitive to the lack of
certain genetic information.
相似文献
62.
Expression of the Th1 chemokine IFN-gamma-inducible protein 10 in the airway alters mucosal allergic sensitization in mice 总被引:2,自引:0,他引:2
Wiley R Palmer K Gajewska B Stämpfli M Alvarez D Coyle A Gutierrez-Ramos J Jordana M 《Journal of immunology (Baltimore, Md. : 1950)》2001,166(4):2750-2759
Although the preliminary characterization of chemokines and their receptors has been prolific, comparatively little is known about the role of chemokines in the evolution of immune responses. We speculate that the preferential recruitment of a particular immune cell population has implications for the short- and long-term features of an adaptive response. To test this hypothesis, we employed adenovirus-mediated gene transfer to express the Th1-affiliated, CXC chemokine IFN-gamma-inducible protein (IP) 10 in the airways of mice undergoing a mucosal sensitization regimen known to result in a Th2-polarized allergic response. This resulted in a approximately 60-75% inhibition of eosinophils in the bronchoalveolar lavage (BAL); these inflammatory changes were accompanied by enhanced IFN-gamma, ablated IL-4, and, peculiarly, unaltered IL-5 and eotaxin levels in the BAL. The effect of IP-10 expression was shown to be dependent on IFN-gamma, as there was no statistically significant reduction in BAL eosinophilia in IFN-gamma knockout mice subjected to the IP-10 intervention. Flow cytometric analysis of mononuclear cells in the lung revealed a approximately 60% reduction in the fraction of CD4(+) cells expressing T1/ST2, a putative Th2 marker, and a parallel increase in the proportion expressing intracellular IFN-gamma following IP-10 treatment. The effect of IP-10 expression at the time of initial Ag encounter is persistent, as mice rechallenged with OVA following the resolution of acute inflammation exhibited reduced eosinophilia and IL-4 in the BAL. Collectively, these data illustrate that local expression of the chemokine IP-10 can introduce Th1 phenomena to a Th2-predisposed context and subvert the development of a Th2 response. 相似文献
63.
Esther Munalula‐Nkandu Paul Ndebele Seter Siziya JC Munthali 《Developing world bioethics》2015,15(3):248-256
We conducted a study to review the consenting process in a vaginal Microbicide feasibility study conducted in Mazabuka, Zambia. Participants were drawn from those participating in the microbicide study. A questionnaire and focus group discussion were used to collect information on participants understanding of study aims, risks and benefits. Altogether, 200 participants took part in this study. The results of the study showed that while all participants signed or endorsed their thumbprints to the consent forms, full informed consent was not attained from most of the participants since 77% (n = 154) of the participants had numerous questions about the study and 34% (n = 68) did not know who to get in touch with concerning the study. Study objectives were not fully understood by over 61% of the participants. Sixty four percent of the participants were not sure of the risks of taking part in the microbicide study. A significant number thought the study was all about determining their HIV status. Some participants were concerned that their partners were not on the trial as they were convinced that being on the study meant that that they had a lifetime protection from HIV infection. The process of obtaining consent was inadequate as various phases of the study were not fully understood. We recommend the need for researchers to reinforce the consenting process in all studies and more so when studies are conducted in low literacy populations. 相似文献
64.
JC Biro 《Theoretical biology & medical modelling》2006,3(1):15-12
Background
Prediction of protein folding and specific interactions from only the sequence (ab initio) is a major challenge in bioinformatics. It is believed that such prediction will prove possible if Anfinsen's thermodynamic principle is correct for all kinds of proteins, and all the information necessary to form a concrete 3D structure is indeed present in the sequence. 相似文献65.
Microsatellite allele frequencies in humans and chimpanzees, with implications for constraints on allele size 总被引:24,自引:6,他引:18
The distributions of allele sizes at eight simple-sequence repeat (SSR) or
microsatellite loci in chimpanzees are found and compared with the
distributions previously obtained from several human populations. At
several loci, the differences in average allele size between chimpanzees
and humans are sufficiently small that there might be a constraint on the
evolution of average allele size. Furthermore, a model that allows for a
bias in the mutation process shows that for some loci a weak bias can
account for the observations. Several alleles at one of the loci (Mfd 59)
were sequenced. Differences between alleles of different lengths were found
to be more complex than previously assumed. An 8-base-pair deletion was
present in the nonvariable region of the chimpanzee locus. This locus
contains a previously unrecognized repeated region, which is imperfect in
humans and perfect in chimpanzees. The apparently greater opportunity for
mutation conferred by the two perfect repeat regions in chimpanzees is
reflected in the higher variance in repeat number at Mfd 59 in chimpanzees
than in humans. These data indicate that interspecific differences in
allele length are not always attributable to simple changes in the number
of repeats.
相似文献
66.
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70.
Structure and organization of the bovine beta-globin genes 总被引:1,自引:0,他引:1
Genomic clones spanning the entire cow beta-globin gene locus have been
isolated and characterized. These clones demonstrate that the linkage of
embryonic-like (epsilon) genes and pseudogenes (psi) to the previously
described fetal (gamma) and adult (beta) genes is as follows: 5'-epsilon
3-epsilon 4-psi 3-beta-epsilon 1-epsilon 2-psi 1- psi 2-gamma-3'. Present
data indicate that, like that of the goat, the fetal and adult genes arose
via block duplication of an ancestral four- gene set:
epsilon-epsilon-psi-beta. This duplication event preceded the divergence of
cows and goats, which occurred greater than or equal to 18-20 Myr ago.
However, cows do not have the additional four-gene block containing a
preadult/stress globin gene (beta C). Furthermore, the cow fetal cluster
contains an extra beta-like pseudogene, which apparently arose by a
small-scale duplication. The fixation of this duplication may indicate a
possible evolutionary role for pseudogenes.
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