Nucleotide sequences of transfer RNA genes in the Pisum sativum chloroplast DNA

Summary Eight transfer RNA (tRNA) genes which were previously mapped to five regions of the Pisum sativum (pea) chloroplast DNA (ctDNA) have been sequenced. They have been identified as tRNA^Val(GAC), tRNA^Asn(GUU), tRNA^Arg(ACG), tRNA^Leu(CAA), tRNA^Tyr(GUA), tRNA^Glu(UUC), tRNA^His(GUG), and tRNA^Arg(UCU) by their anticodons and by their similarity to other previously identified tRNA genes from the chloroplast DNAs of higher plants or from E. gracilis. In addition,two other tRNA genes, tRNA^Gly (UCC) and tRNA^Ile(GAU), have been partially sequenced. The tRNA genes are compared to other known chloroplast tRNA genes from higher plants and are found to be 90–100% homologous. In addition there are similarities in the overall arrangement of the individual genes between different plants. The 5 flanking regions and the internal sequences of tRNA genes have been studied for conserved regions and consensus sequences. Two unusual features have been found: there is an apparent intron in the D-loop of the tRNA^Gly(UCC), and the tRNA^Glu(UUC) contains GATTC in its T-loop.     

Vibration and sound communication in solitary bees and wasps

ABSTRACT. Females of solitary bees ( Colletes cunicularius L.) and of digger wasps ( Bembix rostrata L.) produce buzzing sounds and are known to secrete volatile odours when digging their way from the subterranean nests to the soil surface. The odours allow patrolling males to determine the approximate position of the digging virgin female. The buzzes are measured as substrate-borne sound (soil buzz vibrations) and as air-borne sound (soil buzz sounds). Play-back experiments suggest that the soil buzzes are used by the males as additional cues for localization. Faint buzz sounds are emitted regularly by the male during genital contact in copulation. They may serve to change the receptivity of the female. Intense and broadband buzz sounds are produced by bees of either sex, if restrained from moving, perhaps serving to deter predators.     

Correlation between infection by Rhizobium leguminosarum and lectin on the surface of Pisum sativum L. roots

The lectin on the surface of 4- and 5-dold pea roots was located by the use of indirect immunofluorescence. Specific antibodies raised in rabbits against pea seed isolectin 2, which crossreact with root lectins, were used as primary immunoglobulins and were visualized with fluorescein- or tetramethylrhodamine-isothiocyanate-labeled goat antirabbit immunoglobulin G. Lectin was observed on the tips of newly formed, growing root hairs and on epidermal cells located just below the young hairs. On both types of cells, lectin was concentrated in dense small patches rather than uniformly distributed. Lectin-positive young hairs were grouped opposite the (proto)xylematic poles. Older but still-elongating root hairs presented only traces of lectin or none at all. A similar pattern of distribution was found in different pea cultivars, as well as in a supernodulating and a non-nodulating pea mutant. Growth in a nitrate concentration which inhibits nodulation did not affect lectin distribution on the surface of pea roots of this age. We tested whether or not the root zones where lectin was observed were susceptible to infection by Rhizobium leguminosarum. When low inoculum doses (consisting of less than 10⁶ bacteria·ml^-1) were placed next to lectin-positive epidermal cells and on newly formed root hairs, nodules on the primary roots were formed in 73% and 90% of the plants, respectively. Only a few plants showed primary root nodulation when the inoculum was placed on the root zone where lectin was scarce or absent. These results show that lectin is present at those sites on the pea root that are susceptible to infection by the bacterial symbiont.Abbreviations FITC fluorescein isothiocyanate - TRIC tetramethylrhodamine isothiocyanate     

Pregnant mares' serum gonadotropin source influences fertilization and fresh or thawed embryo development,but the effect is genotype specific

The influence of the source of pregnant mares' serum gonadotropin (PMSG) on the num ber, quality, and in vitro development of mouse embryos before and after freezing was evaluated among three genotypes: N:NIH(S), C57BL/6N, and C3H/HeN-MTV^?. Immature females were given PMSG from one of five commercial sources. Following col lection ( 116 hr later), embryos were evaluated for stage of development, and four-to eight-cell embryos were pooled within genotype and assigned to standardized fresh or freeze-thaw culture trials. Different PMSG sources stimulated the production of different num bers of total embryos (P < 0.05) but not necessarily more embryos suitable for freezing. Differences in embryo production among genotypes indicated that absolute embryo num bers using a single mouse genotype may not accurately reflect the potency of a specific gonadotropin source. The PMSG source also affected the ability of an embryo to survive in culture either immediately after collection or after frozen storage. The effect, however, was genotype specific, with some mouse strains being relatively insensitive to PMSG source, whereas gonadotropin source played a major role in determining in vitro viability in others. Development rates for freshly collected embryos differed, often inconsistently, from those of thawed embryos regardless of the PMSG source used, demonstrating that fresh embryo development cannot be used to estimate expected post-thaw survival. In vitro development of thawed embryos is influenced not only by genotype, but also the source of the gonadotropin used to promote follicular development and oocyte maturation. These findings may explain, in part, the wide variation in embryo viability and culture rates reported among laboratories and intraspecies animal populations.     

虫生真菌蝉拟青霉的研究

观察了蝉拟青霉的无性世代,在24℃下载片培养结果,分生孢子经8hr萌发,24hr普遍形成菌丝,36hr出现产孢结构和产生次代分生孢子。该菌生长合适温度24—26℃,分生孢子萌芽要求相对湿度在90%以上。pH4—12范围均见生长,但以5—6为佳。对10种碳源和9种无机氮源利用检测结果,用葡萄糖作碳源孢子产量高,用果糖作碳源菌丝体产量高。不利用菊糖、L-山梨糖、L-鼠李糖。对KNO_3利用佳,但不能利用NaNO_2,和硫脲。该菌能较强抗紫外辐射。     

Rhizosphere pH along different root zones of Douglas-fir (Pseudotsuga menziesii), as affected by source of nitrogen

Douglas-fir, grown on strongly acid soil (pH-H₂O 3.87), was fertilized with ammonium, nitrate or ammonium nitrate as N-source. Rhizosphere pH along the root axis was measured with microelectrodes. Pure ammonium supply resulted in acidification of the rhizosphere, almost along the entire root axis; only the extreme root tip was slightly alkaline compared with the bulk soil. With nitrate supply, the alkalization of the rhizosphere at the root tip was considerably stronger than with ammonium supply and the length of the alkalization zone greater, extending over the entire growth zone of the root. Acidification of the rhizosphere along the older parts of the root was less pronounced in the case of nitrate. It is concluded that nitrate nutrition enables the plant to protect its most essential root zone from the adverse effects of strong acidity by locally raising the rhizosphere pH.     

Occurrence and localization of an uptake hydrogenase in the filamentous heterocystous cyanobacteriumNostoc PCC 73102

Summary Free-living nitrogen-fixingNostoc PCC 73102, a filamentous heterocystous cyanobacterium originally isolated from coralloid roots of the cycadMacrozamia sp., were examined for the presence of an uptake hydrogenase (H₂ase) enzyme. In vivo and in vitro hydrogen uptake measurements were used to study activities and SDS-PAGE and Western immunoblots to reveal occurrence of the hydrogenase protein. Also, transmission electron microscopy and immunocytological labeling were used to study the cellular and subcellular distribution of H₂ase in theNostoc cells. In vivo measurements demonstrated an active uptake of hydrogen in both light and darkness. Light stimulated in vivo hydrogen uptake with approximately 100%, and this was further doubled by increasing the pH₂, from 56 to 208 M H₂. An in vitro hydrogen uptake of 1.1 mol H₂/ mg (protein)/h was observed when using phenazinemethosulphate as e^–-acceptor. Western immunoblots revealed that a polypeptide with a molecular weight of about 55 kDa was immunologically related to uptake H₂ase holoenzyme purified fromAlcaligenes latus. Immunolocalization demonstrated that the H₂ase protein was located both in heterocysts and vegetative cells. A higher specific labeling was associated with the cytoplasmic membranes where the vegetative cells are in contact with each other and where they actually are dividing into two vegetative cells. Using the particle analysis of an image processor, approximately equal H₂ase-gold labeling per cell area was observed in the nitrogen-fixing heterocysts compared to the photosynthetic vegetative cells. This study also shows that there was no correlation between presence of phycoerythrin and uptake H₂ase activity.Abbreviations H₂ase hydrogenase - IgG immunoglobulin G     

The isolation and characterization of gibberellin-deficient mutants in tomato

Summary In tomato, nine independent EMS-induced mutants representing recessive mutations at three different loci (gib-1, gib-2, and gib-3) were isolated. Six of these have an almost absolute gibberellin requirement for seed germination and elongation growth. In addition, the leaves are darker green, smaller, and changed in structure as compared to wild type. The three other mutants, which germinate without GA, are allelic to specific, nongerminating mutants and have less severe mutant characteristics. The respective loci are situated on three different chromosomes. The genes identified by these mutants control steps in gibberellin biosynthesis, as endogenous gibberellins are strongly reduced.