Regulation of cellular adhesion molecule expression in murine oocytes, peri-implant ation and post-implantation embryos

Expression of the adhesion molecules, ICAM-1, VCAM-1, NCAM, CD44, CD49d (VLA-4, a chain), and CDlla (LFA-1, a chain) on mouse oocytes, and pre- and peri-implantation stage embryos was examined by quantitative indirect immunofluorescence microscopy. ICAM-1 was most strongly expressed at the oocyte stage, gradually declining almost to undetectable levels by the expanded blastocyst stage. NCAM, also expressed maximally on the oocyte, declined to undetectable levels beyond the morula stage. On the other hand, CD44 declined from highest expression at the oocyte stage to show a second maximum at the compacted 8-cell/morula. This molecule exhibited high expression around contact areas between trophecto-derm and zona pellucida during blastocyst hatching. CD49d was highly expressed in the oocyte, remained significantly expressed throughout and after blastocyst hatching was expressed on the polar trophecto-derm. Like CD44, CD49d declined to undetectable levels at the blastocyst outgrowth stage. Expression of both     

Estimation of heterozygosity for single-probe multilocus DNA fingerprints

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.      

Extrapair paternity and egg hatchability in tree swallows: evidence for the genetic compatibility hypothesis?

Tree swallows (Tachycineta bicolor) show one of the highestlevels of extrapair paternity in birds, and there is evidencethat females have control over who fathers their offspring.However, it is unclear which benefits female tree swallows obtainfrom mating with multiple males. Using microsatellite DNA fingerprinting,we studied extrapair paternity in relation to nesting successand male, female, and offspring characteristics. More than 70%of all nests contained extrapair young, and more than half ofall offspring were extrapair. Within broods, the extrapair youngwere often fathered by several males. Despite screening allresident and some floater males, we could identify the biologicalfather of only 21% of all extrapair offspring. All identifiedextrapair males were close neighbors. Extrapair males did notdiffer from within-pair males in any of the measured characteristics,except that the former had larger cloacal protuberances than thelatter. Extrapair males were equally successful in gaining paternityin their own broods as males that did not father extra young.In nests with mixed paternity, extrapair young did not differfrom within-pair young in body size or mass. However, nestswith extrapair young had higher hatching success than nestswithout extrapair young. All examined unhatched eggs were fertilizedand thus hatch failure resulted from embryo mortality. The availabledata are in accordance with the genetic diversity and the geneticcompatibility hypothesis, but not with the good genes hypothesis.     

To What did They Consent? Understanding Consent Among Low Literacy Participants in a Microbicide Feasibility Study in Mazabuka,Zambia

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.     

Amino acid size, charge, hydropathy indices and matrices for protein structure analysis

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.     

Sea urchin Hox genes: insights into the ancestral Hox cluster

We describe the Hox cluster in the radially symmetric sea urchin and compare our findings to what is known from clusters in bilaterally symmetric animals. Several Hox genes from the direct-developing sea urchin Heliocidaris erythrogramma are described. CHEF gel analysis shows that the Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA, and only a single cluster is present, as in lower chordates and other nonvertebrate metazoans. Phylogenetic analyses of sea urchin, amphioxus, Drosophila, and selected vertebrate Hox genes confirm that the H. erythrogramma genes, and others previously cloned from other sea urchins, belong to anterior, central, and posterior groups. Despite their radial body plan and lack of cephalization, echinoderms retain at least one of the anterior group Hox genes, an orthologue of Hox3. The structure of the echinoderm Hox cluster suggests that the ancestral deuterostome had a Hox cluster more similar to the current chordate cluster than was expected Sea urchins have at least three Abd-B type genes, suggesting that Abd-B expansion began before the radiation of deuterostomes.      

Two Novel Tau Antibodies Targeting the 396/404 Region Are Primarily Taken Up by Neurons and Reduce Tau Protein Pathology

Aggregated Tau proteins are hallmarks of Alzheimer disease and other tauopathies. Recent studies from our group and others have demonstrated that both active and passive immunizations reduce Tau pathology and prevent cognitive decline in transgenic mice. To determine the efficacy and safety of targeting the prominent 396/404 region, we developed two novel monoclonal antibodies (mAbs) with distinct binding profiles for phospho and non-phospho epitopes. The two mAbs significantly reduced hyperphosphorylated soluble Tau in long term brain slice cultures without apparent toxicity, suggesting the therapeutic importance of targeting the 396/404 region. In mechanistic studies, we found that neurons were the primary cell type that internalized the mAbs, whereas a small amount of mAbs was taken up by microglia cells. Within neurons, the two mAbs were highly colocalized with distinct pathological Tau markers, indicating their affinity toward different stages or forms of pathological Tau. Moreover, the mAbs were largely co-localized with endosomal/lysosomal markers, and partially co-localized with autophagy pathway markers. Additionally, the Fab fragments of the mAbs were able to enter neurons, but unlike the whole antibodies, the fragments were not specifically localized in pathological neurons. In summary, our Tau mAbs were safe and efficient to clear pathological Tau in a brain slice model. Fc-receptor-mediated endocytosis and the endosome/autophagosome/lysosome system are likely to have a critical role in antibody-mediated clearance of Tau pathology.