Susceptibility to erbB-induced erythroblastosis is a dominant trait of 151 chickens.

Rous-associated virus-1 (RAV-1)-induced erythroblastosis results from proviral insertions into or viral transductions of the c-erbB region of the epidermal growth factor gene. Most chickens develop low incidences (less than 5%) of RAV-1-induced erythroblastosis. However, an inbred line of chickens (151) suffers high incidences (approximately 80%) of RAV-1-induced erythroblastosis. Analysis of 151, K28, and (K28 X 151) X K28 chickens for susceptibility to RAV-1-induced erythroblastosis revealed that susceptibility to RAV-1-induced erythroblastosis is a dominant trait of line 151 chickens. Analysis of 151 X K28 and K28 chicks for susceptibility to the induction of erythroblastosis by two new c-erbB-transducing viruses (avian erythroblastosis virus strains AEV-5005 and AEV-5009) revealed that susceptibility to transformation by new c-erbB-transducing viruses is also a dominant trait of 151 chickens. We think it is likely that both of these dominant traits are encoded by the same gene or genes. Our hypothesis is that this gene (or genes) potentiates the ability of the transmembrane and cytoplasmic domains of the epidermal growth factor receptor to transform cells.     

Streptomycin resistance is inherited as a recessive Mendelian trait in a Nicotiana sylvestris line

Summary The SR180 cell line has been isolated in a callus culture derived from a haploid Nicotiana sylvestris (n = X = 12) plant by its ability to proliferate on a selective medium containing 2,000 g/ml streptomycin sulphate. From the cell line diploid plants have been regenerated. The SR180 selfs are resistant to streptomycin. Streptomycin sensitivity in F1, and a 31 (sensitive to resistant) segregation in F2 indicate that resistance in the SR180 mutant is the result of a recessive Mendelian mutation.     

Identification and mapping of a major dominant quantitative trait locus controlling seeds per silique as a single Mendelian factor in Brassica napus L.

One putative quantitative trait locus (QTL) for seeds per silique (SS), cqSS.A8, was identified using a double haploid (DH) population in Brassica napus, and near-isogenic lines (NILs; BC(3)F(1)) for cqSS.A8 were developed. However, the flanking markers from cqSS.A8 showed no significant difference using single-marker analysis, even though the frequency distribution of SS in the BC(3)F(1) was bimodal, suggesting that one novel locus existed. In this study, we characterized the effects of this locus in the NILs and used a published linkage map to determine its location. A three-step approach was designed for mapping the locus in the NILs (BC(3)F(2)): (1) determining the individual BC(3)F(2) genotype at the locus using a progeny test; (2) identifying amplified fragment length polymorphism (AFLP) markers linked to the locus using a combination of AFLP and bulked segregant analysis; and (3) determining the location and effects of this locus. QTL analysis in the BC(3)F(2) revealed that this locus explained 85.8 and 55.7 % of phenotypic variance for SS and SL, respectively. Its additive and dominant effects on SS were 6.1 and 5.7, respectively. The locus was validated using a DH population by composite interval mapping and located to linkage group C9 (designated as qSS.C9). Mapping qSS.C9 was undertaken using 230 extremely low-SS plants of a BC(4)F(1) population containing 807 plants. We found that qSS.C9 delimited a 1.005-Mb interval including 218 predicted genes in the reference Brassica rapa (Chiifu-401). These results will greatly facilitate map-based cloning of qSS.C9 and seed yield improvement in rapeseed.     

Minireview. Evidence that dopamine is a neurotransmitter in peripheral tissues

In the CNS, dopamine (DA) is a recognized neurotransmitter as well as a precursor for norepinephrine (NE) and epinephrine (EPI). In contrast to the CNS, DA has been assumed to be only a precursor in peripheral tissues. There is now, however, considerable evidence to support the hypothesis that it may function as a neurotransmitter and/or cotransmitter in peripheral tissues in addition to being a precursor. In this minireview we summarize evidence supporting the view that DA plays a role of its own in peripheral neurotransmission.     

Evidence that polygalacturonase is a virulence determinant in Erwinia carotovora.

Polygalacturonase (PG) was purified from Erwinia carotovora EC. A hybrid cosmid, pSH711, that encodes PG activity but not pectate lyase activity was identified from an E. carotovora genomic library by an immunological screening method. A cell extract of Escherichia coli cells containing pSH711 was able to produce plant tissue maceration when spotted on carrot, potato, or turnip slices. In addition, the E. coli strain containing this plasmid was able to macerate carrot, potato, and turnip slices. Our results suggest that PG plays an important role in soft-rot disease.     

Evidence that bombesin releases extragastric gastrin in man

Bombesin-induced gastrin release from extragastric sources has been investigated in two groups of patients without gastric antrum: 11 patients with total gastrectomy and 11 patients with subtotal (Billroth II) gastrectomy. A 30-min bombesin infusion (5 ng . kg-1 . min-1) caused a prompt significant gastrin increase (P less than 0.05) in both groups of patients. The gastrin response to bombesin was significantly (P less than 0.005) lower in patients without antral tissue than in the control group (n = 7). The individual peak gastrin responses, in totally (TG) and subtotally (SG) gastrectomized patients, were significantly over basal levels (TG: peak 100.3 +/- 12 vs. basal 62.8 +/- 9.1, P less than 0.005; SG: peak 96.9 +/- 9.4 vs. basal 72.4 +/- 6.8, P less than 0.001; pg/ml, mean +/- S.E.M.). These data indicate that bombesin acts not only on antral G cells, but on all gastrin cells in the gastrointestinal tract.     

Evidence that gonadotrophin surge-attenuating factor exists in man

This review article summarizes the evidence provided by in-vivo and in-vitro studies suggesting that the human ovary produces a nonsteroidal factor distinct from inhibin which participates in the control of gonadotrophin secretion from the pituitary. This factor has been called gonadotrophin surge-attenuating factor (GnSAF) and is defined as attenuating the endogenous surge in luteinizing hormone (LH) in superovulated women by reducing the pituitary response to LH-releasing hormone. In-vivo bioactivity of GnSAF has been detected during the follicular phase of superovulated cycles; in-vitro studies have shown activity of this factor in human follicular fluid. From a physiological point of view, a hypothesis is proposed that GnSAF attenuates the amplitude of the positive effect of oestradiol on gonadotrophin secretion during the follicular phase of the human menstrual cycle and therefore plays an important role in controlling ovulation. If GnSAF is isolated, it may have several clinical applications including contraception.     

Evidence that type I diabetes and thyrogastric autoimmunity have different genetic determinants.

The prevalences of autoimmune endocrine disease and relevant organ-specific autoantibodies were determined in 141 patients with type I (insulin-dependent) diabetes and their families. All available members of the families were genotyped for HLA. Islet-cell antibody was found in 10 (4%) out of 248 unaffected siblings, all of whom were genetically potential cases of diabetes. One developed classical symptoms six months later. In contrast, thyroid and gastric parietal-cell antibodies occurred independent of the HLA-linked susceptibility to diabetes. These results suggest that different genes control the production of these autoantibodies and the susceptibility to type I diabetes.     

Evidence that autoimmunity in NZB mice is caused by a defect in immune specificity rather than a generalized defect in tolerance of self-antigens

NZB mice which were already producing anti-erythrocyte autoantibodies were not able to respond to their own liver F antigen, thus providing evidence that their autoimmunity is not caused by a generalized breakdown in self-tolerance mechanisms. The specificity of autoantibodies produced in the spontaneous hemolytic anemia was different from that of antierythrocyte antibodies induced in normal mice and in young NZB mice by injections of rat erythrocytes. This indicates that the B-cell clones which can be triggered by heterologous antigen are different from those responsible for the NZB disease; the latter clones may not exist in normal mice.     

Evidence that tamoxifen is a histamine antagonist

Recently we reported that both the triphenylethylene antiestrogen tamoxifen, and the novel compound N,N-diethyl-2-[(4 phenylmethyl)-phenoxy]-ethanamine. HCl (DPPE), which is selective for the antiestrogen binding site, may be histamine antagonists and have suggested that the antiestrogen binding site may be a growth-promoting histamine receptor different from H1 and H2 (?H3). We now show that along with established H1-antagonists, tamoxifen and DPPE specifically block the histamine-induced (H1) contraction of canine tracheal smooth muscle in the order: pyrilamine = hydroxyzine greater than tamoxifen = 4-hydroxytamoxifen greater than DPPE. The H1-antagonist hydroxyzine, which competes about equally with DPPE for the antiestrogen binding site, is up to 10(3) times stronger than DPPE in blocking histamine-induced muscle contraction. This shows that H1 antagonism is distinct from binding to the antiestrogen binding site and suggests that if the latter is a histamine receptor, it is not H1; presumably tamoxifen and DPPE compete for this novel site in addition to, and with greater affinity than, H1.     

Evidence that cortical granule formation is a periovulatory event in marsupials.

Formation of cortical granules was examined in superovulated oocytes from three marsupial species, brushtail possums (Trichosurus vulpecula) tammar wallabies (Macropus eugeniii) and grey short-tailed opossums (Monodelphis domestica) and in oocytes obtained during natural cycles in Macropus eugenii. Superovulation was induced by pregnant mares' serum gonadotrophin/gonadotrophin-releasing hormone (PMSG/GnRH) protocols and natural ovulation by removal of pouch young. Oocytes were collected after ovariectomy or by laparoscopically guided follicle aspiration into Hanks balanced salt solution (HBSS) supplemented with either 2.5% fetal calf serum (FCS) or 2.5% bovine serum albumin (BSA). Ovulated oocytes were collected by removing and flushing the oviducts with HBSS and fixed immediately for electron microscopy. There were no differences in the morphology or timing of formation of cortical granules between superovulated and naturally cycling animals. Cortical granules were absent from germinal vesicle (GV) stage follicular oocytes before the luteinizing hormone (LH) surge in all species. Dark cortical granules, similar in appearance to those seen in the oocytes of eutherian mammals, were found just beneath the plasma membrane (9 per 100 microns of plasma membrane) of preovulatory oocytes at germinal vesicle, metaphase 1 or anaphase 1 stages. In addition, they contained a number of less electron-dense cortical granules (12 per 100 microns plasma membrane). The cortical cytoplasm of preovulatory oocytes was rich in Golgi complexes actively involved in vesicle formation. Large numbers of dark cortical granules (90 per 100 microns plasma membrane) were found only in ovulated oocytes. A small number of cortical granules of lighter electron density were also present in ovulated oocytes. This suggests that the marsupial oocyte is following a very different timetable for cortical granule formation and accumulation from eutherian mammals and that oocytes of marsupials may not achieve cytoplasmic maturity until after ovulation. The significance of these events for fertilization and development remains to be established.