Studies on Factors which promote Germination of Raspberry Seeds

The germination of raspberry seeds was favoured by applyingcertain combinations of chemical pretreatment before givingup to six weeks of moist-chilling before sowing, by adding 500p.p.m. gibberellic acid just before sowing, and by providingsupplementary light after sowmg. The most useful chemical pretreatmentwas 20 minutes with concentrated sulphuric acid followed bysix days with 1.0 per cent calcium hypochlorite containing anexcess of calcium hydroxide. For some seed samples such pretreatmenteliminated the need for a subsequent period of moist-chilling,but for others a six-week period of moist-chilling was stillrequired. Pretreatment with higher concentrations than 1.0 percent of calcium hypochiorite, 0.5 per cent of sodium hypochlorite,or 1.0 per cent of thiourea, or pretreatment with the statedconcentrations of these chemicals but in each case without theaddition of calcium hydroxide, frequently delayed or preventedgermination. The results of these studies are in accord withthe hypothesis that the germination capacity of raspberry seedsis determined by interactions between growth inhibitors andpromoters. Such substances have been detected m blackberry seedsand it is suggested that a similar situation exists in seedsof the raspberry.     

Movements of self-marked caddisfly larvae, Chyrnda centralis (Trichoptera: Limnephilidae), in a Sierran spring stream, California, U.S.A.

SUMMARY. 1. The tendency of larvae of Chyranda centralis to mark themselves by adding coloured plastic segments to their cases was used to study instream movements of the species. Plastic strips of different colours were placed at measured distances down a small spring stream and larvae cut pieces and incorporated them in their cases.
2. Over 50% of the marked population moved upstream into cooler water prior to pupation in an exceptionally dry year. The greatest distance moved upstream by a single larva was 56.9m, In a wet year, when daytime stream temperatures were cooler, 11–28% of the marked population moved upstream. Downstream movement occurred in both years late in the fifth instar.
3. Larvae selected yellow in preference to other colours in laboratory tests and they preferred heavy, textured plastic to light, smooth plastic as they neared pupation.
4. Upstream movements, found also in Desmana bethula (Trichoptera: Limnephilidae) in the same spring stream, may be an adaptation for avoiding pupation in areas of high temperature, low oxygen concentration, or intermittent flow.     

A Secondary Alcohol Dehydrogenase from Tetrahymena furgasoni1

ABSTRACT. Dehydrogenase activity with hydroxysteroids has been observed in Tetrahymena furgasoni (formerly T. pyriformis strain W), and the enzyme responsible has been isolated from this organism. The purified dehydrogenase is active with a variety of steroid alcohols at apparent K_m values ranging from 0.2 to 4.0 mM. The C-3 hydroxyl of ring A of the steroid nucleus is the preferred position of oxidation. However, a variety of other secondary alcohols are also substrates, with apparent K_m values for 2-butanol, 2-pentanol, and cyclohexanol of 880, 1000. and 150 mM, respectively. With both steroidal and nonsteroidal alcohols. NAD is the preferred co-substrate, although low activity with NADP is observed. Evidence is presented that the activity with secondary alcohols, whether steroidal or not, is the property of a single protein species.     

Diagnostic Genetic Marker That Differentiates Eastern Fox Squirrels From Eastern Gray Squirrels

Abstract The Delmarva fox squirrel (Sciurus niger cinereus) has been listed as endangered by the United States Department of Interior since 1967. A high-priority task for the recovery of this taxon is to determine its current geographic distribution. Toward this end, we have identified a microsatellite locus that unambiguously differentiates Delmarva fox squirrels from eastern gray squirrels (S. carolinensis), which frequently co-occur with Delmarva fox squirrels. Analysis of this marker in noninvasively collected hair samples will allow unequivocal identification of localities occupied by Delmarva fox squirrels with a minimum investment of funds, time, and effort because handling individuals will be unnecessary. This protocol will expedite site review in connection with the Endangered Species Act consultation process.