Biomedical subjects

M B Zhang

Publications and source records attributed to M B Zhang.

7 recordsLinked to original sources

PubMed1991

Laboratory transmission of Jamestown Canyon and snowshoe hare viruses (Bunyaviridae: California serogroup) by several species of mosquitoes.

The ability of 14 species of mosquitoes to biologically transmit Jamestown Canyon virus was tested. Four species not previously described as vectors of that virus transmitted to suckling mice. Among membrane-fed mosquitoes with disseminated infections, field-collected Aedes canadensis (1/3), Anopheles punctipennis (1/12), Coquillettidia perturbans (2/14) and a laboratory strain of Ae. epactius (19/67) transmitted virus. Two species were tested for their ability to transmit snowshoe hare virus: field-collected Ae. provocans (4/20) and Ae. abserratus-punctor (2/20) successfully transmitted to suckling mice. Evidence regarding the role of these species as field vectors is summarized.

Aedes↗

PubMed1990

Covalent labeling of the cocaine-sensitive catecholamine transporter.

Xylamine is an alkylating agent that is a substrate for and specific irreversible inhibitor of the cocaine-sensitive catecholamine transporter that functions in catecholamine reuptake into neurons and PC12 cells. [3H]xylamine prominently labels nine PC12 proteins; the relative xylamine-alkylation of a Mr 54,000 protein was decreased by cocaine and increased in the case of a PC12 variant, B9, which is deficient in catecholamine transport. [3H]xylamine labels no such protein in another transport variant, MPT1. We propose that this Mr 54,000 protein 1) is a component of the catecholamine transporter, 2) is present in B9 cells but in a conformation that reduces transporter activity and makes alkylation by xylamine more likely, and 3) is absent in MPT1 cells. Nerve growth factor treatment restores transporter activity in B9 cells but not in other transporter-deficient variants.

Alkylation↗

PubMed1990

Transforming growth factor alpha and a PC12-derived growth factor induce neurites in PC12 cells and enhance the survival of embryonic brain neurons.

We have identified and characterized a 5000-Da protein that induces neurite outgrowth from PC12 pheochromocytoma cells, enhances the survival of embryonic rat brain neurons in primary culture, and induces the multiplication of embryonic rat brain astrocytes in primary culture. The factor is produced by a flat cell PC12 variant that expresses the activated ras oncogene after transfection of the gene. The factor resembles transforming growth factor alpha (TGF alpha) and epidermal growth factor (EGF) in that it induces anchorage-independent colony formation of normal rat kidney cells in soft agar and competes with EGF for binding to the EGF receptor. Rat TGF alpha and human TGF alpha also induce neurite outgrowth from PC12 and enhance the survival of embryonic brain neurons. The PC12 variant-derived factor can be distinguished from TGF alpha and EGF immunologically and by migration rates on reversed-phase high-performance liquid chromatography.

Animals↗

PubMed1990

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-resistant, flat-cell PC12 variants having a partial loss of transformed phenotype.

We have cloned and characterized two variants of PC12 cells. MPT1 cells were selected by their resistance to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and variant 2068 was isolated nonselectively as a large, flat-cell variant commonly occurring in PC12 cultures. Variant 2068 cells also exhibit resistance to MPTP. Karyotype analysis revealed that these variants are true derivatives of wild-type PC12 cells; however, each variant is tetraploid, whereas the wild-type parent is diploid. The two variants contain an altered level and composition of lactate dehydrogenase isoenzymes, which could account for a previously described difference in lactate metabolism. Both variants exhibit a partial loss of transformed phenotype in culture in that they are nonrefractile, grow in monolayers, and fail to multiply in soft agar. We suggest that this alteration in transformed phenotype may result in altered mitochondria and lactate dehydrogenase and thus account for their resistance to MPTP. Compared with wild-type PC12 cells, MPT1 cells have a decreased level of fos mRNA and an increased level of myc mRNA; the latter results from an increased level of transcription of exon 1 of the myc gene. Studies with hybrid cells obtained by fusing MPT1 cells with wild-type-like cells show that most, but not all, of the parameters of the MPT1 phenotype predominate.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

PubMed1990

Isolation of Jamestown Canyon virus (California serogroup) from Aedes mosquitoes in an enzootic focus in Michigan.

Twenty isolates of Jamestown Canyon virus were obtained from adult females of 5 Aedes species collected at the Houghton Lake Wildlife Research Area, Missaukee County, in north-central Michigan between 1985 and 1989. Fourteen were from Aedes provocans, and 6 were from 4 other snowmelt Aedes species. One isolate of trivittatus virus and one Cache Valley-like virus were also obtained. Seasonal succession patterns for numerous mosquito species were recorded over 4 years. The temporal association of adult mosquito emergence, virus isolations, and infection and seroconversion of sentinel deer suggest that Ae. provocans is a primary enzootic vector of Jamestown Canyon virus in that focus. We hypothesize that Ae. provocans provides an overwintering reservoir for Jamestown Canyon virus at the study site. A large dry ice-baited "tent trap" was the most productive method for collecting numerous aedine and other mosquito species.

Aedes↗

PubMed1989

Recently introduced Aedes albopictus in the United States: potential vector of La Crosse virus (Bunyaviridae: California serogroup).

A population of Aedes albopictus collected in 1986 in Harris County, Texas, was evaluated for its vector competence with 4 California serogroup viruses (Jamestown Canyon, Keystone, La Crosse and trivittatus). Rates of midgut infection, dissemination of virus beyond the midgut and oral transmission to suckling mice were markedly different for the 4 viruses in a pattern representative of the antigenic relationships known for the California serogroup. Only La Crosse virus was shown to be efficiently transmitted by this recently introduced mosquito population. The results suggest that populations of Ae. albopictus originating from the Harris County population might well be as efficient in transmitting La Crosse virus as are populations of the natural mosquito vector. Aedes triseriatus, from the midwestern La Crosse virus enzootic region. The public health implications of these results are discussed in relation to the rapid spread of Ae. albopictus throughout the eastern half of the United States and into regions where La Crosse virus is known to be enzootic.

Aedes↗

PubMed1986

PC12 variants deficient in catecholamine transport.

We have isolated PC12 cell variants deficient in transporter-mediated uptake of 3,4-dihydroxyphenylethylamine (dopamine). The variants either were obtained nonselectively, or they were selected by resistance to guanethidine or N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Dopamine uptake into guanethidine-resistant cells occurred with a decreased Vmax; the Km for dopamine and inhibition by guanethidine were normal. MPTP-resistant cells lacked the capacity to take up dopamine. Most of the variants resembled wild-type PC12 in their response to nerve growth factor and the storage and secretion of dopamine. MPTP-resistant cells exhibited several deficiencies in addition to dopamine transport, i.e., no measurable storage of dopamine or acetylcholine and no observable response to nerve growth factor. Wild-type and variant cells were compared with respect to the labeling of cell proteins with [3H]xylamine, which binds covalently to certain proteins apparently only after entering PC12 via the catecholamine transporter. When intact variant cells were used, there was markedly reduced labeling of the proteins by [3H]xylamine. Almost all of these proteins were readily labeled when cell homogenates were exposed to [3H]xylamine. However, MPTP-resistant cells were missing three of these proteins. Northern blot analysis with cDNA clones revealed that the MPTP-resistant cells had markedly reduced levels of several specific mRNA species.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗