Regulation of rat ovarian cell growth and steroid secretion

A cultured rat ovarian cell line (31 A-F(2)) was used to study the effect of growth factors (epidermal growth factor [EGF] and fibroblast growth factor [FGF]), a survival factor (ovarian growth factor [OGF]), a hormone (insulin), and an iron-binding protein (transferring) on cell proliferation and steroid production under defined culture conditions. EGF and insulin were shown to be mitogenic (half-maximal response at 0.12 nM and 0.11 muM, respectively) for 31A-F(2) cells incubated in serum-free medium. EGF induced up to three doublings in the cell population, whereas insulin induced an average of one cell population doubling. FGF, OGF, and transferrin were found not to have any prominent effect on cell division when incubated individually with 31A-F(2) cells in serum-free medium. However, a combination of EGF, OGF, insulin, and transferrin stimulated cell division to the same approximate extent as cells incubated in the presence of 5 percent fetal calf serum. EGF or insulin did not significantly affect total cell cholesterol levels (relative to cells incubated in serum-free medium) when incubated individually with 31A-F(2) cells. However, cell cholesterol levels were increased by the addition of OGF (250 percent), FGF (370 percent), or a combination of insulin and EGF (320 percent). Progesterone secretion from 31A-F(2) cells was enhanced by EGF (25 percent), FGF (80 percent), and insulin (115 percent). However, the addition of a mitogenic mixture of EGF, OGF, insulin, and transferrin suppressed progesterone secretion 150 percent) below that of control cultures. These studies have permitted us to determine that EGF and insulin are mitogenic factors that are required for the growth of 31A-F(2) cells and that OGF and transferrin are positive cofactors that enhance growth. Also, additional data suggest that cholesterol and progesterone production in 31A-F(2) cells can be regulated by peptide growth factors and the hormone insulin.     

Coexistence of two species of Binella Motchulsky (Coleoptera: Ptiliidae) and the significance of their adaptation to different temperature ranges

Abstract.

• 1 Ptinella aptera and Ptinella errabunda often coexist where their distributions overlap.
• 2 The ecological requirements of P.aptera and P.errabunda are similar. Both are generalized mycetophages restricted to the same subcortical habitat of trees in a particular state of decay. Relative humidity appears important in determining habitat suitability for both species, neither of which survived in laboratory regimes below approximately 100% relative humidity.
• 3 In laboratory studies the beetles differed in their response to temperature. Recorded maxima for activity and rate of increase were at higher temperatures for P.aptera than for Perrabunda.
• 4 Temperatures which ‘Ptinella were exposed to in the laboratory occur in natural conditions under bark. Their effects on the species’ distributions are considered.
• 5 The differential temperature adaptations of P.aptera and P.errabunda were probably evolved in allopatry, in response to different environmental conditions. In view of this, it is unreasonable to infer past interspecies competition from these niche differences.
• 6 The niche difference between coexisting Ptinella species is discussed in the light of current ideas concerning the relative importance of competition and other factors in natural communities.

     

The association of Xiphinema diversicaudatum (Micoletsky) with strawberry latent ringspot and arabis mosaic viruses in a raspberry plantation

An outbreak of strawberry latent ringspot virus (SLRV) in a plantation of Mailing Jewel raspberry coincided with the greatest abundance of the nematode vector, Xiphinema diversicaudatum. Arabis mosaic virus (AMV) was not detected in the crop but was, together with SLRV, in many weed species present. AMV was transmitted through the seed of Poa annua, Capsella bursa-pastoris and Senecio vulgaris and SLRV through the seed of Mentha arvensis. X. diversicaudatum were more numerous within the rows than between them and vertical sampling showed that most occurred between 4 and 12 in depth in both locations. Monthly sampling showed that egg laying occurred from April to July; populations increased to a peak in late autumn but declined during the winter, resulting in about a twofold annual increase in numbers. Females, males and juveniles transmitted AMV and SLRV to cucumber seedlings, and in the absence of plants the nematode retained AMV for 112 days and SLRV for 84 days.     

Abscisic-acid-deficient mutants at the aba gene locus of Arabidopsis thaliana are impaired in the epoxidation of zeaxanthin

Abstract. The xanthophyll content of wild type and abscisic acid (ABA) - deficient mutants of pea and Arabidopsis thaliana was determined. The wilty mutant of pea was indistinguishable from the non-mutant control. In contrast, plants homozygous for mutant alleles at the aba locus of Arabidopsis were very different from wild type. In these mutants, zeaxanthin accumulated to abnormally high levels. The major carotenoids, violaxanthin and 9'- cis -neoxanthin were virually absent from the mutant chromatograms. It was concluded that the aba genetic lesion impairs the epoxidation of zeaxanthin to violaxanthin and that this results in an inability to accumulate ABA. This provides clear evidence that zeaxanthin is a precursor of ABA.     

Sinapine Leakage from Non-viable Cabbage Seeds

Seeds leak many compounds during the early phases of germinationand seed viability may be associated with differential leakageof specific compounds. Leakage of a fluorescent compound fromnon-viable cabbage (Brassica oleracca var. capitata L.) wasdocumented and studies were performed to identify the fluorescentcompound. Imbibed samples of both heat-killed (HK) and viablecabbage seeds were submerged in a viscous colloidal gel. After2 h to 4 h, a fluorescent halo was observed under U.V. lightaround the heat-killed seed but not around the viable seed.Viable and HK seeds were imbibed in water for 8 h and the pHof the leachate was adjusted to either 7 or 10. The absorptionspectra of leakage from HK seeds revealed peak values at 322nm and 388 nm at pH 7 and 10, respectively. This pattern wasnot observed from viable seed leakage. Two-dimensional paperchromatography was conducted on the HK seed leachate. Four fluorescentspots were observed after development first with BAW (n-butanol:acetic acid: water, 4: 1: 5 by vol.) followed by 6% acetic acid.One of the fluorescent spots (spot 3) was studied further dueto its observed intensity. Sinapine thiocyanate was preparedfrom rapeseed oilmeal and used as a reference sample. Absorptionspectra of spot 3 and sinapine thiocyanate were similar at bothpH 7 and 10. Spot 3 had identical R_F values using three solventsystems and identical colour reactions in five tests comparedto sinapine thiocyanate. It was concluded that sinapine wasthe major compound responsible for the fluorescent leakage fromHK cabbage seeds. Key words: Leachate, viability, Brassica     

Seed Viability Determinations in Cabbage Utilizing Sinapine Leakage and Electrical Conductivity Measurements

A need exists for the development of rapid seed quality teststhat determine viability (defined as the ability to germinate)without the necessity for completion of germination. In cabbage(Brassica oleracea var. capitata L.) the compound sinapine,a choline ester of sinapic acid, has been shown to leak fromheat-killed (HK.) but not from viable seeds. Sinapine leakagewas studied as a more accurate method for identifying viableseeds than the conductivity test. After an 8 h soak, a 26-folddifference in sinapine leakage was detected between HK and viableseeds (as measured by the absorbance at 388 nm at pH 12) comparedto a 4-fold difference measured by electrolyte leakage. Theremainder of the studies were conducted on two seedlots of thesame cultivar. Viability was predicted on the same seed by assessingleakage from individual seeds into the soak water using threemethods; soak water colour, absorbance at 388 nm, and electricalconductivity. This information was compared with the actualgermination of each seed for the two seedlots. For both seedlots,the presence of sinapine in seed soak water (detected eitherby a yellow solution colour at high pH or by high absorbance),identified more seeds that were non-viable than the partitioncoefficient calculated from conductivity measurements (76%,72% and 28% of non-viable seeds were identified, respectively).It is proposed that leakage of sinapine is a better predictorof cabbage seed viability than electrical conductivity. Key words: Seed deterioration, seed leakage, germination prediction     

Resistance to halo-blight in the Cambridge accessions V4604 and V4058 of Phaseolus beans

V4604, a Cambridge University accession of Phaseolus vulgaris, had a high degree of leaf resistance to race 1 of Pseudomonas phaseolicola and partial resistance to race 2. Genetic control of resistance to race 1 was by a major dominant gene which is also present in the cv. Red Mexican. The partial resistance of V4604 to race 2 was under polygenic control, as was the low level resistance to race 2 in V4058.