Intracellular cyclic AMP produces effects opposite to those of cyclic GMP and calcium on shape and motility of neuroblastoma cells.

We have directly evaluated the effects of various intracellular second messengers including cyclic nucleotides, calcium ion, and inositol polyphosphates on shape and motility of differentiating mouse neuroblastoma cells. The messengers were microinjected into cells and the responses of the soma, neurite, and growth cone were monitored using time-lapse video microscopy. Each messenger altered cell shape and motility in a characteristic manner. Cyclic AMP promoted lamellipodial expansion, neurite outgrowth, and motility. The other injected messengers opposed motility. Cyclic GMP caused motile structures to freeze and to retract permanently, while the inhibitory effects of calcium injection were concentration-dependent. Small calcium injections affected specifically actin-containing motile structures which froze and retracted temporarily. Intermediate calcium injections caused a strong contraction at the site of injection in all cells. With large injections, cells retracted long neurites, rounded up, and frequently began vigorous blebbing that continued to cell death. Injections of the inositol polyphosphates IP3(1,4,5) and IP4(1,4,5,6) mimicked the effects of small calcium injections, as did electrical stimulation that elicited action potentials. The results suggest that in mouse neuroblastoma cells, intracellular cAMP elevation increases cytoskeletal organization and promotes neurite extension perhaps through an enhancement of cell-substratum adhesion. On the other hand, a rise of intracellular cGMP or intracellular calcium interferes directly with the function and organization of the actin-microfilament system. The integrated action of these second messenger systems may, therefore, operate in vivo to allow substances released from neighboring cells to regulate neuronal architecture.     

Genetic localization of Hao-1, blind-sterile (bs), and Emv-13 on mouse chromosome 2.

The blind-sterile (bs) mutation in the mouse was localized on Chromosome 2 between Hao-1 and Emv-13. N2 progeny from a backcross between congenic female 129.AKR-bs Emv-13 mice and (129.AKR-bs/bs x Mus musculus molossinus) F1 male mice were typed by analysis of isozyme variants for Hao-1, visible inspection for bs, and restriction fragment length polymorphism for Emv-13 and Emv-15. Comparison between markers on mouse Chromosome 2 and corresponding markers on human chromosomes suggest that the human homolog of bs will be located on 20q11-q13.     

An interspecific linkage map of mouse chromosome 15 positioned with respect to the centromere

We have used an interspecific backcross between C57BL/6J and Mus spretus to derive a molecular genetic linkage map of chromosome 15 that includes 25 molecular markers and spans 93% of the estimated length of chromosome 15. Using a second interspecific backcross that was analyzed with a centromere-specific marker, we were also able to position our map with respect to the chromosome 15 centromere. This map provides molecular access to many discrete regions on chromosome 15, thus providing a framework for establishing relationships between cloned DNA markers and known mouse mutations and for identifying homologous genes in mice and humans that may be involved in disease.     

A molecular genetic linkage map of mouse chromosome 18 reveals extensive linkage conservation with human chromosomes 5 and 18

An interspecific backcross between C57BL/6J and Mus spretus was used to generate a molecular genetic linkage map of mouse chromosome 18 that includes 23 molecular markers and spans approximately 86% of the estimated length of the chromosome. The Apc, Camk2a, D18Fcr1, D18Fcr2, D18Leh1, D18Leh2, Dcc, Emb-rs3, Fgfa, Fim-2/Csfmr, Gnal, Grl-1, Grp, Hk-1rs1, Ii, Kns, Lmnb, Mbp, Mcc, Mtv-38, Palb, Pdgfrb, and Tpl-2 genes were mapped relative to each other in one interspecific backcross. A second interspecific backcross and a centromere-specific DNA satellite probe were used to determine the distance of the most proximal chromosome 18 marker to the centromere. The interspecific map extends the known regions of linkage homology between mouse chromosome 18 and human chromosomes 5 and 18 and identifies a new homology segment with human chromosome 10p. It also provides molecular access to many regions of mouse chromosome 18 for the first time.     

Assignment of a novel protein tyrosine phosphatase gene (Hcph) to mouse chromosome 6.

Hematopoietic cell phosphatase (Hcph) was identified by amplification of conserved protein tyrosine phosphatase sequences from a myeloid cell line and is predominantly expressed in hematopoietic cells. Hcph is unique in containing two, tandemly repeated, src-homology 2 domains in the amino terminal region of the phosphatase. Using a genomic probe in interspecific backcross analysis, the murine Hcph gene maps to mouse Chromosome 6 and is tightly linked to the Tnfr-2 and Ly-4 genes.     

Localization of the human gene allowing infection by gibbon ape leukemia virus to human chromosome region 2q11-q14 and to the homologous region on mouse chromosome 2.

Retrovirus receptors remain a largely unexplored group of proteins. Of the receptors which allow infection of human and murine cells by various retroviruses, only three have been identified at the molecular level. These receptors include CD4 for human immunodeficiency virus, Rec-1 for murine ecotropic virus, and GLVR1 for gibbon ape leukemia virus. These three proteins show no homology to one another at the DNA or protein level. Therefore, work to date has not shown any general relationship or structural theme shared by retroviral receptors. Genes for two of these receptors (CD4 and Rec-1) and several others which have not yet been cloned have been localized to specific chromosomes. In order to assess the relationship between GLVR1 and other retroviral receptors, we mapped the chromosome location of GLVR1 in human and mouse. GLVR1 was found to map to human chromosome 2q11-q14 by in situ hybridization and somatic-cell hybrid analysis. This location is distinct from those known for receptors for retroviruses infecting human cells. Glvr-1 was then mapped in the mouse by interspecies backcrosses and found to map to chromosome 2 in a region of linkage conservation with human chromosome 2. This mouse chromosome carries Rec-2, the likely receptor for M813, a retrovirus derived from a feral Asian mouse. These data raise the interesting possibility that Rec-2 and Glvr-1 are structurally related.     

Effect of treatment with glutaraldehyde-fixed myelin basic protein-liposomes on active induction and passive transfer of experimental allergic encephalomyelitis in Lewis rats

Guinea pig myelin basic protein (MBP)-liposomes were prepared and fixed with 0.2% glutaraldehyde (GA). Lewis rats were treated with glutaraldehyde-fixed MBP-liposomes (MBP-L-GA) or with cytochrome-c-liposomes (CYC-L-GA), 7 days before and 7 days after challenge with MBP in CFA. Rats treated with MBP-L-GA, but not with CYC-L-GA, were very well protected against the clinical manifestations of EAE. The protection was better than that obtained after treatment with conventional MBP-liposomes (without glutaraldehyde). Furthermore, when grown in vitro for 72 hr in the presence of MBP, lymphocytes from rats treated with MBP-L-GA and challenged with MBP in CFA exhibited a marked decrease in their ability to transfer EAE to normal syngeneic recipients.     

Vernonia galamensis,Potential new crop source of epoxy acid

Vernonia galamensis is a good source of seed oil rich in epoxy acid, which can be used to manufacture plastic formulations, protective coatings, and other products. Seed from a natural stand in Ethiopia contained 31% epoxy acid. Under cultivation in Kenya, this unimproved germplasm produced a substantial yield of seed with 32% epoxy acid. This African species has good natural seed retention and is a promising new crop for semiarid tropical areas.