Associations between heterozygosity and morphological variance

Recent studies have contrasted the expression of phenotypic traits, such as variance in morphological characters, with levels of genetic variation (heterozygosity) as determined by electrophoretic analysis of protein-coding loci. The theoretical basis for interpreting significant covariation stems in part from Lerner's work on genetic homeostasis, which predicts that within populations increased heterozygosity will produce decreased morphological variance, owing to a buffering effect of heterosis during development. However, the prediction for the relationship between genic heterozygosity and the variance of morphological traits among populations is unclear. To determine if a relationship existed between heterozygosity and morphological variance, we compared estimates of heterozygosity and morphological variance across 15 population samples of the fox sparrow and 17 samples of the pocket gopher. The estimates of morphological variance included coefficients of variation for each character and the variance of individual scores about the population mean in a principal components analysis. Although several recent studies have reported a significant relationship between heterozygosity and morphological variance, we found that the two measures do not covary significantly.     

Gel electrophoretic analysis of proteins in human milk and colostrum

Protein patterns of skim milk and fat globule phases were relatively unchanging throughout 9 months lactation, the only notable differences being a rise in lysozyme and a decline up to 6 months with increase thereafter in lactoferrin. Profound changes in protein patterns of the breast secretion were observed during the first week postpartum. True colostrum, in which peptides of sIgA dominate the protein patterns, exists for at most the 2 initial days of secretion. Proteins of mature milk are not coordinated to appear in the colostral secretion simultaneously. A band corresponding to alpha-lactalbumin is present from the initial secretion; that for beta-casein emerges approximately 2 days layer.     

Enterotoxemia in rabbits.

The presence of Clostridium perfringens Type E iota toxin was confirmed from the cecal contents of 23 of 46 rabbits which died of enteritis complex. The most consistent lesions observed were hemorrhage and edema in the cecum. Rabbit toxicity tests showed the toxic cecal contents were lethal for young rabbits unless incubated with Clostridium perfringens Type E antiserum.     

Cutaneous and pulmonary aspergillosis in rabbits.

Cutaneous and pulmonary aspergillosis was diagnosed in rabbits. Dichotomous branching, septate hyphae typical of Aspergillus spp were observed in cystic hair follicles. Atypical, short, knobby mycelia with radiating projections were seen in nodular lesions in the lung.     

Differences between individuals in high-molecular weight glycoproteins from mammary epithelia of several species

Milk fat globules are secreted by envelopment in plasma membrane of the lactating cell. SDS-gel electrophoresis of proteins from this membrane has revealed differences between milk donors in two mucin-like glycoproteins. One of these glycoproteins resolves in 3% acrylamide stacking gel and the other in 4% running gel. The proteins vary in number of bands (one or two) and band mobilities. This polymorphism arises, at least in part, from expression of hypervariable genes. In this study, gel electrophoretic evidence of similar polymorphism in glycoproteins from cow, chimpanzee, horse and human milks is presented. In distinction to the other species, the cow expressed only one of these proteins which was detected in the running gel at Mr 180,000 to 200,000. The electrophoresis pattern for this protein from six cows was highly varied with respect to number (one or two) and position of bands. Peanut agglutinin, wheat germ agglutinin and concanavalin A all were bound specifically by bands of the bovine glycoprotein. Binding of concanavalin A distinguishes the bovine protein from the two human glycoproteins. Further studies of species differences should help shed light on the evolution of these unique glycoproteins and their possible functions in mother and young.     

Basement membrane assembly, stability and activities observed through a developmental lens.

Basement membranes are cell surface associated extracellular matrices containing laminins, type IV collagens, nidogens, perlecan, agrin, and other macromolecules. Biochemical and ultrastructural studies have suggested that basement membrane assembly and integrity is provided through multiple component interactions consisting of self-polymerizations, inter-component binding, and cell surface adhesions. Mutagenesis in vertebrate embryos and embryoid bodies have led to revisions of this model, providing evidence that laminins are essential for the formation of an initial polymeric scaffold of cell-attached matrix which matures in stability, ligand diversity, and functional complexity as additional matrix components are integrated into the scaffold. These studies also demonstrate that basement membrane components differentially promote cell polarization, organize and compartmentalize developing tissues, and maintain adult tissue function.     

Identification of a series of C(21)O(2) pregnanes from fecal extracts of a pregnant black rhinoceros (Diceros bicornis minor).

Fecal extracts from a pregnant black rhinoceros, Diceros bicornis, were analyzed by radioimmunoassay, HPLC, and by GC-mass spectrometry. From 40 g of dried feces a total of 33 pregnanes in the C(21)O(2) series, including a number of novel 17 alpha epimers were identified. No progesterone was recovered. The principal progesterone metabolite by mass was 5 alpha-pregnan-3 beta,20 alpha-diol (44.5%), which did not cross react with the antibody used in our RIA. The antibody recognized progesterone and pregnanes with 20-one configuration, which when combined made up less than 15% of the total C(21)O(2) steroid mass. Of the 33 pregnanes in the C(21)O(2) series identified, 81%, by mass, were in the 5 alpha-configuration. These results are compared with studies in other rhinoceros species (Asian and Sumatran) in which pregnanes in the 5 beta-configuration are the major fecal metabolites, and the white rhinoceros in which pregnanes in the 5 alpha-configuration are the dominant form.     

The 3'-terminal consensus sequence of rotavirus mRNA is the minimal promoter of negative-strand RNA synthesis.

We used an in vitro template-dependent replicase assay (D. Chen, C. Zeng, M. Wentz, M. Gorziglia, M. Estes, and R. Ramig. J. Virol. 68:7030-7039, 1994) to identify the cis-acting signals required for replication of a genome segment 9 template from the group A rotavirus strain OSU. The replicase phenotypes for a panel of templates with internal deletions or 3'-terminal truncations indicated that no essential replication signals were present within the open reading frame and that key elements were present in the 5' and 3' noncoding regions. Chimeric constructs containing portions of viral sequence ligated to a nonviral backbone were generated to further map the regions required for in vitro replication of segment 9. The data from these constructs showed that the 3'-terminal seven nucleotides of the segment 9 mRNA provided the minimum requirement for replication (minimal promoter). Analysis of additional chimeric templates demonstrated that sequences capable of enhancing replication from the minimal promoter were located immediately upstream of the minimal promoter and at the extreme 5' terminus of the template. Mutational analysis of the minimal promoter revealed that the 3'-terminal -CC residues are required for efficient replication. Comparison of the replication levels for templates with guanosines and uridines at nucleotides -4 to -6 from the 3' terminus compared with levels for templates containing neither of these residues at these positions indicated that either or both residues must be present in this region for efficient replication in vitro.