Low responsiveness of six-rowed genotypes to androgenesis in barley does not have a pleiotropic basis.

A heterozygous mutant for the two- and six-rowed character was isolated in the barley cultivar Igri through application of sodium azide to isolated microspore cultures and posterior regeneration. Six-rowed and two-rowed homozygotic plants were subsequently identified in the self-pollinated M2 progenies of the original heterozygous M1. Detailed molecular markers confirmed the isogenic nature of this recovered mutant and the original cultivar Igri. A comparative study of the anther culture response of this six-rowed induced mutant vs. diploid 'Igri' was performed to assess whether the two- or six-rowed gene influences anther culture response in barley through a pleiotropic effect or via linkage disequilibrium. No significant differences for any of the recorded variables throughout the in vitro regeneration process were detected between the 'Igri' six-rowed mutant and any of their two-rowed isogenic lines. This suggests that row-type association with anther culture response in barley cultivars is due to the effect of a tight linkage with other genes directly responsible for androgenic response.     

Goldston syndrome: report of a case.

Cerebrohepatorenal malformation is a rare familial disorder characterized by typical renal lesions combined with Dandy-Walker malformation, and congenital hepatic fibrosis. In this case report, a male premie with the diagnosis of cerebrorenal syndrome or so called Goldston syndrome is presented. Besides the rarity of this syndrome, this case is the second reported patient diagnosed prenatally.     

Effects of antimutagenic flavourings on SCEs induced by chemical mutagens in cultured Chinese hamster cells

Effects of antimutagenic flavourings such as vanillin, ethylvanillin, anisaldehyde, cinnamaldehyde, coumarin and umbelliferone on the induction of SCEs by MMC were investigated in cultured Chinese hamster ovary cells. None of these 6 flavourings showed any SCE-inducing activity by themselves. However, an obvious increase in the frequencies of SCEs was observed when MMC-pretreated cells were cultured in the presence of each flavouring. All these compounds have either an alpha, beta-unsaturated carbonyl group or a carbonyl functionality neighbouring the phenyl group which may react with an enzyme SH-group and cause higher-order structure changes. SCE-enhancing effects of vanillin were further investigated on 6 other kinds of mutagens. Vanillin was also effective on SCEs induced by EMS, ENNG, ENU or MNU. On the other hand, MMS- or MNNG-induced SCEs were not influenced at all by vanillin. SCE-enhancing effects of vanillin seemed to be dependent on the quality of lesions in DNA.     

Evidence for the retention of genetic variation in Erodium seed dormancy by variable rainfall

Summary The periodic occurrence of summer/early autumn precipitation in the California annual grassland can result in the formation of early and late emerging cohorts of Erodium botrys and E. brachycarpum. The occurrence of early rainfall and the timing of such rainfall are highly variable from year to year. A series of field watering experiments in 1980–81 were used to simulate early emergence conditions that would result from significant rainfall (1 cm) occurring in mid-July, late August, and mid-September. Net reproduction was used to estimate fitness differentials between Erodium cohorts emerging in response to a watering treatment (early emerging cohorts) and Erodium cohorts emerging with the onset of winter rains in mid-October (late emerging cohorts). Survival was lower and gross reproduction was higher among early emerging cohorts than late emerging cohorts. For both species, net reproduction of the early cohort was lower than that of the late cohort under the July watering treatment and higher than that of the late cohort under the August watering treatment.Early cohorts, formed in response to rainfall in mid-September, 1982, were also compared demographically to later cohorts emerging in October. Compared to late cohorts, net reproduction, gross reproduction and survival were higher for the early cohorts.Common garden experiments indicate that differences in the duration of seed dormancy between the progenies of early and late emerging plants reflect a significant genetic component. Progency produced by early cohorts of E. brachycarpum from all three watering treatments possessed more extended seed dormancy than progeny of late cohorts. In E. botrys, progeny from early cohorts emerging in response to the July watering treatment were also more dormant than late progeny. In contrast, early cohorts of E. botrys emerging in response to the September watering treatment produced seed less dormant than seed produced by late cohorts. When combined with demographic data, indicating that fitness differentials between early and late cohorts varied with changes in the date of early emergence, genetic results suggest that year to year variation in early rainfall may act to retain genetic variation in the duration of seed dormancy.     

Water and sodium transport: effects of calcium channel blocker and calmodulin antagonists on the apical and basolateral membranes of amphibian epithelia

Ca2+ channel blocker (sensit) and calmodulin antagonists (thioridazine, perphenazine, oxyprothepine) applied to the mucosal side of frog urinary bladder, weakened the response of epithelial cells to vasopressin. Thioridazine (2.7 X 10(-5) mol X l-1) and sensit (1.7 X 10(-4) mol X l-1) applied to the serosal side rapidly increased the permeability of the epithelia for sodium and potassium ions along the concentration gradient (from serosa to mucosa). The same concentrations of these blockers when applied to the mucosal side of frog urinary bladder selectively decreased vasopressin stimulated water permeability and did not influence ionic permeability. Both thioridazine and sensit decreased the short-circuit current across frog skin. The results show that the Ca2+ channel blocker and the calmodulin antagonists tested influenced water and ionic transport across the epithelial cell membranes, and had different effects upon the apical and the basolateral cell membranes.     

Detailed structural analysis of exposed domains of membrane-bound Na+,K+-ATPase. A model of transmembrane arrangement

Exposed regions of the alpha- and beta-subunits of membrane-bound Na+,K+-ATPase were in turn hydrolyzed with trypsin. Resistance of the beta-subunit to proteolysis was shown to be due mainly to the presence of disulfide bridge(s) in the molecule. A model for the spatial organisation of the enzyme in the membrane was proposed on the basis of detailed structural analysis of extramembrane regions of both subunits.     

Immunoaffinity-purified opiate receptor specifically binds the delta-class opiate receptor ligand, cis-(+)-3-methylfentanylisothiocyanate, SUPERFIT

Using an antibody generated against the opiate receptor on NG108-15 cells, we recently purified the putative receptor from this hybrid cell line. We herein report that the purified receptor complex specifically binds tritiated cis-(+)-3-methylfentanylisothiocyanate (SUPERFIT), with the predominant binding associated with a 58 kDa polypeptide chain. Consistent with these findings is the in situ labeling of a 58 kDa protein with [3H]SUPERFIT on NG108-15 cells.     

Genetic Hitchhiking and the Evolution of Reduced Genetic Activity of the Y Sex Chromosome

We report experiments designed to test homology dependence for gene conversion between duplicated chromosomal sequences in cultured mammalian cells. The experimental system is such that gene conversion events not associated with reciprocal exchange are recoverable. For this study four plasmids were constructed. Each contains a different duplication of the herpes simplex virus thymidine kinase (HSV tk) gene sequence. In particular, the interacting sequences share different lengths of homology. Our results indicate that for shared homologies between 295 base pairs (bp) and 1.8 kilobase pairs (kbp) in length, conversion is efficient with the rate being directly proportional to the extent of homology. In contrast, conversion with either 200 bp or 95 bp of homology is inefficient, and the rate is reduced at least seven- or 100-fold, respectively, relative to that observed with 295 bp of homology. These results are consistent with the notion that greater than 200 bp of homology are required for efficient gene conversion between repeated chromosomal sequences in mammalian cells.