Divergence of mate recognition systems among conspecific populations of the plethodontid salamander Desmognathus santeetlah (Amphibia: Plethodontidae)

The disjunct geographic distribution of plethodontid salamanders of the genus Desmognathus provides excellent opportunities to test whether populations diverge in mate recognition systems so as to result in sexual incompatibility. Previous work has shown that sexual incompatibility may exist both among conspecific populations and between different species in this genus. Populations of the Santeetlah dusky salamander, Desmognathus santeetlah , are found at higher elevations in three mountain ranges in the southern Appalachian Mountains of eastern North America, where they are sympatric with congeneric species of similar body size. We report that statistically significant levels of sexual incompatibility exist among populations of D. santeetlah collected from across the species' range. Contrary to popular belief, but in accord with a growing body of empirical literature, aspects of mate recognition systems can diverge among conspecific populations of salamanders, resulting in incidental sexual incompatibility.     

Natural and experimental hybridization inArmeria (Plumbaginaceae):A. villosa subsp.carratracensis

An experimental crossing program was carried out in order to test the hypothesis thatArmeria villosa subsp.carratracensis, a serpentine endemic from Southern Spain, is of hybrid origin. Fruit-set and mainly pollen stainability data in artificial hybrids demonstrate that internal interspecific barriers are weak. Two generations of backcrossing with the two putative parents —A. colorata andA. villosa subsp.longiaristata— can restore pollen stainability to an average of 83.2 and 68.7, respectively. A morphometric analysis of 148 specimens belonging to parental species, different artificial hybrid generations and wild putative hybrid race shows that (1) morphological characters have a strong genetic basis and thus are good markers in identifying hybrids and introgression inArmeria; (2) artificial backcrossing produces in morphometrical characters a variation which conforms in both trend and magnitude to what is commonly attributed in the wild to introgression; (3) the position of the putative hybrid race is intermediate between the two parental species used in the program. These results are in accordance with the hypothesis of hybrid origin ofA. villosa subsp.carratracensis. Natural and experimental hybridization inArmeria, I     

PCR cloning of a protein-coding part of the thioredoxin gene fromStreptomyces aureofaciens

Summary The method of two-stage half-specific amplification was described and successfully used in the isolation of the protein-coding part of the thioredoxin gene from Streptomyces aureofaciens BMK. The efficiency of a new PCR modification for the specific amplification of the target DNA fragments (genes) with unknown sequences is compared with the used half-specific PCR. The determined target sequence demonstrates the highest homology with the thioredoxin genes from Corynebacterium nephridii C-1 and Anabaena 7119.     

Isolation and preliminary characterization of ferritin from clover seeds

Ferritin from clover (Trifolium subterraneum) seeds was isolated and characterized. It was shown to contain polypeptide units of 28–26.5 kDa. The apparent molecular mass of the native protein was 560 kDa. The average iron cores were 4 nm in diameter and contained 1300 iron atoms, with Fe:P = 4:1. Purified clover apoferritin was shown to be functional by means of iron uptake experiments. Plots of initial velocities of iron uptake (at pH 6.7) into clover and horse spleen apoferritins were found to have similar profiles.     

湖南、江西铀矿床区土壤中(B.cereus)分离及形态学比较

从湖南、江西两地铀矿床区采集土壤样品 13份 ,用选择性培养基从 10 -3 稀释的平板中分离到卵黄反应阳性菌 2 38株 (其中xw1,xw2 无该菌 )。从中筛选 8株 ,经纯化培养 ,对 8株进行了显微镜和电镜的形态观察 ,其形态为典型的杆菌 ,大小为 1.2～ 1.4μm× 2 .6～ 3.4μm ,芽孢为椭圆或橄榄果实形。没有孢囊和伴孢晶体 ,周生鞭毛。生理生化分析结果证明 ,8株均为典型的蜡状芽孢杆菌 (Bacilluscereus)。     

Improved yield of apple leaf protoplasts from in vitro cultured shoots by using very young leaves and adding L-methionine to the shoot medium

Protoplast isolation from apple leaf tissue of in-vitro cultured shoots is possible if very young leaves from buds are used. Digestible leaves are found in apple shoots of the subculture kerö 14 days after transferring the shoot and of M26 some days later.The yield of protoplasts is considerably improved if the apple shoots are cultured in a medium containing L-methionine (0.5 mM).     

Isolation and culture of soybean hypocotyl protoplasts

Summary Protoplasts were isolated seedling hypocotyls of soybean (Glycine max), and cultured in both liquid and agarose-solidified, modified K8P medium. Nuclear staining revealed that only 2% of protoplasts lacked a nucleus, 93% contained a single nucleus, and 5% contained more than one. Maximum protoplast yields and subsequent division frequencies, in liquid medium, were obtained from 5 days-old seedlings. Maximum division frequencies (54%) were obtained from hypocotyl protoplasts plated at a density of 5×10⁴ ml⁻¹. Using different osmolality reduction régimes for liquid cultures, hypocotyl protoplasts developed into green, nodular callus, similar to that which has previously given rise to shoot buds in perennialGlycine species. This tissue, however, did not produce shoot buds in soybean. N. H. was supported by a SERC CASE studentship and a postdoctoral fellowship from Shell Research Ltd., Sittingbourne, Kent, UK.     

The isolation and identification of the prosthetic group released from a bound form of abscisic acid

A bound form of abscisic acid, herein called adduct, has been isolated from peas and barley and has been shown to release methyl abscisate upon mild acid hydrolysis. Mass spectrometry of the methyl abscisate released by ²H₂SO₄ in ²H₂O showed that the remainder of adduct was linked as an enolate of the ketone of the moiety that releases methyl abscisate. Some evidence is adduced to suggest that adduct is a metabolic precursor of abscisic acid. The implications of the distribution of adduct between roots and shoots for the plant's response to stress is discussed.     

Sex pheromones of Spilonota ocellana and Spilonota laricana

The sex pheromones of Spilonota ocellana D. & S. and Spilonota laricana Hein. (Lepidoptera: Tortricidae) were identified by chemical analysis and field trapping. Female moths of the two species produce (Z)-8-tetradecenyl acetate, (Z)-8-tetradecen-1-ol and dodecyl acetate in almost the same proportions (98:1:1 and 97:3:1). Males of both species were best attracted to a blend of 10:1 to 1:1 Z8-14Ac:Z8-14OH. This indicates that mating barriers other than sex pheromones exist between sympatric populations.