XY sex reversal syndrome in the mare: clinical and behavioral studies,H-Y phenotype

Summary An inherited genetic disorder causes XY embryos of the horse to develop as mares. On the basis of our study of 38 such mares, we have identified four grades or classes of XY sex reversal according to this scheme: class I, nearly normal female, of which some are fertile; class II, female with gonadal dysgenesis, normal mullerian development; calss III, intersex mare with gonadal dysgenesis, abnormal mullerian development, enlarged clitoris; class IV, virilized intersex characterized by high levels of testosterone. In general, class I and calss II mares were typed H-Y antigen-negative whereas class III and class IV mares were typed H-Y antigen-positive.     

Lateral segregation of neutrophil chemotactic receptors into actin- and fodrin-rich plasma membrane microdomains depleted in guanyl nucleotide regulatory proteins

Subcellular fractions were prepared from human neutrophils desensitized at 15 degrees C with stimulatory doses of the photoaffinity derivative F-Met-Leu-Phe-N epsilon-(2-(rho-azido[125I]salicylamido)ethyl-1,3'- dithio-propionyl)-Lys. The covalently labeled receptors were found in a membrane fraction of higher density than those from cells preexposed to ligand at 4 degrees C but not desensitized. The denser fraction (rho approximately equal to 1.155 g/cc) was the cellular locus of the membrane associated cytoskeletal proteins, actin, and fodrin, as detected immunologically on western blots. The light fraction (rho approximately equal to 1.135), cosedimented with neutrophil plasma membrane markers, plasma membrane guanyl nucleotide regulatory proteins, and several characteristic polypeptides identified by SDS-PAGE, including a major 72-kD species. The photoaffinity-labeled species in either case showed the same mobility on SDS-PAGE (Mr = 50,000-70,000) corresponding to previously reported values for N-formyl chemotactic receptors. These labeled receptors were sensitive to proteolysis after exposure of the intact photoaffinity-labeled cells to papain at 4 degrees C. We conclude that (a) the fractions isolated are probably derived from different lateral microdomains of the surface of human neutrophils; (b) the higher density fraction contains occupied N-formyl-chemotactic receptors previously shown to have been converted, to a high affinity, slowly dissociating form coisolating with neutrophil cytoskeleton and implicated in the termination of formyl peptide-induced neutrophil activation; and (c) the translocation of receptors to these microdomains may serve to compartmentalize receptors and perhaps regulate the interaction of the receptor/G-protein transduction pair.     

Crystallization and preliminary X-ray analysis of nonglycosylated tissue inhibitor of metalloproteinases-1, N30QN78Q TIMP-1

A nonglycosylated (N₃₀QN₇₈Q) form of the human tissue inhibitor of metalloproteinases, TIMP-1, has been prepared and crystallized in a form suitable for X-ray diffraction analysis. Small single crystals have been grown using sodium tartrate as a precipitant. The crystals are in space group P2₁, with cell dimensions a = 35.28, b = 53.95, c = 48.56, and β = 96.0°. There is a single molecule of TIMP-1 in the asymmetric unit. The crystals diffract to at least 2.3 Å resolution. Complete data have been collected to 2.9 Å and a search for heavymetal derivatives is in progress. © 1993 Wiley-Liss, Inc.     

Reconstitution of a physical complex between the N-formyl chemotactic peptide receptor and G protein. Inhibition by pertussis toxin-catalyzed ADP ribosylation.

Photoaffinity-labeled N-formyl chemotactic peptide receptors from human neutrophils solubilized in octyl glucoside exhibit two forms upon sucrose density gradient sedimentation, with apparent sedimentation coefficients of approximately 4 and 7 S. The 7 S form can be converted to the 4 S form by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) with an EC50 of approximately 20 nM, suggesting that the 7 S form may represent a physical complex of the receptor with endogenous G protein (Jesaitis, A. J., Tolley, J. O., Bokoch, G. M., and Allen, R. A. (1989) J. Cell Biol. 109, 2783-2790). To probe the nature of the 7 S form, we reconstituted the 7 S form from the 4 S form by adding purified G protein. The 4 S form, obtained by solubilizing GTP gamma S-treated neutrophil plasma membranes, was incubated with purified (greater than 95%) Gi protein from bovine brain (containing both Gi alpha 1 and Gi alpha 2) or with neutrophil G protein (Gn), and formation of the 7 S complex was analyzed on sucrose density gradients. The EC50 of 7 S complex formation induced by the two G proteins was 70 +/- 25 and 170 +/- 40 nM for Gn and Gi, respectively. No complexation was measurable when bovine transducin (Gt) was used up to 30 times the EC50 for Gn. The EC50 for Gi was the same for receptors, obtained from formyl peptide-stimulated or unstimulated cells. The addition of 10 microM GTP gamma S to the reconstituted 7 S complex caused a complete revision of the receptor to the 4 S form, and anti-Gi peptide antisera immunosedimented the 7 S form. ADP-ribosylation of Gi prevented formation of the 7 S form even at 20 times the concentration of unribosylated Gi normally used to attain 50% conversion to the 7 S form. These observations suggest that the 7 S species is a physical complex containing N-formyl chemotactic peptide receptor and G protein.     

Assignment to chromosome 16 of a gene necessary for the expression of human mitochondrial glutamate oxaloacetate transaminase (aspartate aminotransferase) (E.C. 2.6.1.1.)

A gene necessary for the expression of human mitochondrial glutamate oxaloacetate transaminase (GOT-2) has been assigned to chromosome 16 on the basis of an immunochemical analysis of human-mouse somatic cell hybrids. Mitochondrial GOT cosegregates with adenine phosphoribosyl transferase (E.C. 2.4.2.7.).     

Presence of two forms of fumarase (fumarate hydratase E.C. 4.2.1.2) in mammalian cells: Immunological characterization and genetic analysis in somatic cell hybrids. Confirmation of the assignment of a gene necessary for the enzyme expression to human chromosome 1

Two major forms of fumarate hydratase have been resolved in extracts prepared from a wide variety of mammalian cells by electrophoresis. Fractionation experiments with human and mouse cells suggest that one form (the slower migrating) is localized in the mitochondria, whereas the other form is predominant in the cytoplasm. Analysis of the segregation of the enzyme forms in human-mouse somatic cell hybrids indicates that a gene(s) necessary for the expression of both forms can be assigned to human chromosome 1 (confirmation of a previous assignment by van Someren et al., 1974). Electrophoretic analysis suggests that the two forms may be interrelated. Furthermore, they both exhibit identical reactivity toward anti-fumarate hydratase antiserum. It is suggested that a modification of one form may occur in vivo and that the modification may be important in determining the intracellular localization of the enzyme.     

African Herald snakes,Crotaphopeltis, show population structure for a widespread generalist but deep genetic divergence for forest specialists

The African colubrid snake genus Crotaphopeltis currently comprises six species and occurs throughout sub-Saharan Africa. The most widespread of these, Crotaphopeltis hotamboeia, inhabits most biomes, aside from rainforest and hyper-arid regions, and its catholic niche has presumably facilitated substantial gene flow. Despite this, the geographical range is large enough that ecological or physical barriers might exist, facilitating allopatric diversification. In contrast, most of the other species are habitat specialists with limited distributions (e.g., Crotaphopeltis tornieri) and would be expected to show strong genetic structure. We therefore examined species boundaries within Crotaphopeltis in a phylogenetic context using five markers (16S, cyt b, ND4, c-mos, and RAG-1) for four of the six species. Species delimitation methods included two coalescent-based and one barcoding approach. Widespread geographical sampling of C. hotamboeia allowed examination of genetic structuring across its range. The species status of Crotaphopeltis barotseensis, C. degeni, and C. hotamboeia was confirmed, whereas the Afromontane species C. tornieri comprised two candidate species. Crotaphopeltis hotamboeia did not show cryptic speciation, although its phylogeographic structure corresponded with the spatiotemporal pattern of the African savanna. Our results show how the heterogeneous African environment could influence genetic partitioning of habitat specialist and generalist species at broad geographical scales.