Physical mapping of inhibin beta-A in domestic cattle

SCO-spondin, a glycoprotein of the subcommissural organ/Reissner's fiber complex: evidence of a potent activity on neuronal development in primary cell cultures

In the cattle, SCO-spondin was shown to be a brain-secreted glycoprotein specifically expressed in the subcommissural organ (SCO), an ependymal differentiation located in the roof of the Sylvian aqueduct. Furthermore, SCO-spondin makes part of Reissner's fiber (RF), a structure present in the central canal of the spinal cord. Sequencing of overlaping cDNA inserts after successive screening of a cattle SCO cDNA expression library allowed characterization of the complete sequence of this novel protein. Conserved domains were identified including twenty-six thrombospondin type 1 repeats (TSRs), nine low-density lipoprotein receptor LDLr type A domains (LDLRA), two epidermal growth factor EGF-like domains, and homologies to mucins and the von Willebrand factor were found in the amino- and carboxy- termini. In addition, SCO-spondin shows a unique arrangement "in mosaic" of these domains. The putative function of SCO-spondin in neuronal differentiation is discussed regarding these features and homologies with other developmental molecules of the central nervous system exhibiting TSR domains, and involved in axonal guidance.To correlate molecular and functional features of SCO-spondin, we tested the effect of oligopeptides whose sequences include highly conserved regions of the TSRs, LDLRA repeats, and a potent site of attachment to glycosaminoglycan, on cortical and spinal cord neurons in primary cell cultures. Peptides corresponding to SCO-spondin TSRs markedly increased adhesivity and neuritic outgrowth of cortical neurons and induced disaggregation of spinal cord neurons. Thus, SCO-spondin is a candidate to interfere with neuronal development and/or axonal guidance during ontogenesis of the central nervous system in modulating side-to-side and side-to-substratum interactions, and in promoting neuritic outgrowth. RF proper has a wide range of activity on neuronal differentiation, including survival, aggregation, and disaggregation effects and neurite extension of cortical and spinal cord neurones "in vitro." Thus, the SCO/RF complex may interact with developmental processes of the central nervous system including the posterior commissure and spinal cord differentiation.

Anchoring of bovine chromosomes 4, 6, 7, 10, and 14 linkage group telomeric ends via FISH analysis of lambda clones

We report the placement of 34 new microsatellite (ms) markers, isolated from a lambda phage genomic clone library, on the bovine genetic map by linkage to published markers. Five of these markers lie at or near the ends of linkage groups and are used to establish chromosomal coverage and orientation. Fluorescence in situ hybridization (FISH) analysis demonstrates that the linkage groups on the U.S. Meat Animal Research Center (MARC) map extend to the telomeric region of Chromosomes (Chrs) 7 and 10. Linkage groups on Chrs 4, 6, and 14 appear to be less inclusive.

Synteny mapping in river buffalo

The cosegregation of ten coding loci has been investigated, in a panel of 37 somatic cell hybrids resulting from the fusion of a hamster cell line and river buffalo lymphocytes, by use of Southern hybridization technique. Five syntenic groups, TCRB-PGY3, ASS-ABL, FUCA1P-CRYG, MBP-YES1, and CGN1-ACTA1, previously assigned to cattle as U13, U16, U17, U28, and U29 respectively, were also found to be syntenic in buffalo. Based on the extensive syntenic conservation and banding homology between cattle and river buffalo, comparative mapping predicts the localization of these syntenic groups on river buffalo Chromosomes (Chrs) :BBU7, BBU12, BBU2q, BBU22, and BBU4q respectively as they have been previously localized on cattle Chrs BTA4, BTA11, BTA2, BTA24 & BTA28.

FISH mapping of the alpha-S2 casein gene on river buffalo and cattle chromosomes identifies a nomenclature discrepancy in the bovine karyotype

A mixture of five genomic clones spanning the alpha-S2 casein gene (CSN1S2) were mapped to river buffalo (Bubalus bubalis L.) and cattle (Bos taurus L.) chromosomes by fluorescence in situ hybridization (FISH) and R-banding. Clear probe hybridization signals were detected on river buffalo chromosome 7q, band 32, and the homologous cattle chromosome. These mapping data allow the indirect assignment of the entire cattle U15 syntenic group to river buffalo chromosome 7. The assignment of U15 to river buffalo chromosome 7 is discussed in the light of chromosomal nomenclature discrepancies involving the homologous cattle chromosome.

Thirteen loci physically assigned to sheep chromosome 2 by cell hybrid analysis and in situ hybridization

Sheep x hamster cell hybrids containing sheep metacentric Chromosome (Chr) 2 were produced by fusing blood leukocytes from normal sheep with hamster auxotrophic Ade F-minus mutants. Cell clones that were isocitrate dehydrogenase 1 (IDH1) positive were cytogenetically characterized, confirming that they contained sheep Chr 2. The following loci were newly assigned by Southern hybridization to sheep Chr 2: lipoprotein lipase (LPL), glycoprotein-4-beta galactosyltransferase 2 (GGTB2), neurofilament light polypeptide (68 kDa; NEFL), surfactant-associated protein 2 (SFTP2), lymphocyte-specific protein tyrosine kinase (LCK), and nebulin (NEB). These new assignments and the in situ localization of gelsolin (GSN) to sheep Chr 2pter-p24 are consistent with the predicted homology of cattle Chr 8 (U18) with sheep Chr 2p, and of cattle Chr 2 (U17) with sheep 2q. In addition, the assignment by cell hybrid analysis of loci previously mapped to Chr 2 in sheep, viz., cholinergic receptor, nicotinic, delta polypeptide (CHRND), collagen type III alpha 1 (COL3A1), fibronectin 1 (FN1), isocitrate dehydrogenase (IDH1), and villin 1 (VIL1), confirmed the localization of sheep syntenic group U11 to this chromosome. By nutritional selection and complementation of the hamster auxotrophic Ade F mutation, the multifunctional enzyme locus phosphoribosylaminoimidazolecarboxamide formyltransferase (AICAR transformylase)/IMP cyclohydrolase (inosinicase) (provisionally given the symbol PRACFT) has also been newly assigned to sheep Chr 2. This report significantly extends the number of loci physically mapped to sheep Chr 2 and confirms its close homology with cattle Chrs 2 and 8.

Seven loci on human chromosome 4 map onto sheep chromosome 6: a proposal to restore the original nomenclature of this sheep chromosome

Seven new loci, casein alpha-S1 (CSN1S1), casein alpha-S2 (CSN1S2), casein beta (CSN2), the Hardy-Zuckerman 4 feline sarcoma viral (v-kit) oncogene homolog (KIT), albumin (ALB), phosphodiesterase cyclic GMP (rod receptor) beta polypeptide (PDEB), and complement component 1 (IF), were assigned to sheep Chromosome (Chr) 6 by Southern hybridization to a panel of chromosomally characterized sheep x hamster cell hybrids. By isotopic in situ hybridization, CSN2 was regionally localized to sheep Chr (OOV) 6q22-q31, anchoring this syntenic group of markers on to OOV6 and confirming its homology at a molecular and cytological level with cattle Chr 6. The assignment of these loci, from PDEB (located on human Chr 4p16.3) to IF (on HSA4q24-q25), and the observation that interleukin 2 (IL2, on HSA4q26-q27) and tryptophan 2,3-dioxygenase (TDO2, on HSA4q31) are not located on OOV6, is further evidence of the close evolutionary relationship of sheep and cattle and the conserved synteny in these species of this extensive region of human Chr 4. On the basis of this conserved synteny, and the similar G- and Q-banding patterns of this chromosome in cattle and sheep, we propose that this sheep chromosome be numbered as 6, not 4 as recommended by ISCNDA (1990).