Distribution,abundance and food of commercial fish in the Black Volta and the Volta man-made lake in Ghana during its first period of filling (1964–1966). I. Mormyridae

Summary As analysed from fish landings for different parts of the Volta Lake, mormyrids have not established themselves in the new lacustrine environment during the first two years after the formation of the Lake. While they form a substantial part of the fish catches in the Black Volta, especially during the dry season, in the Lake they occur regularly in low numbers, only in the northern parts influenced by the river waters. The major factor limiting the establishment of mormyrids in the Volta Lake may be the deoxygenation of the deep water layers, but other factors may also be involved.All mormyrids from the Black Volta are insectivorous and this tendency has not substantially changed in the Lake. Species utilizing to any great extent rheophilic bottom fauna in the Black Volta have an especially low occurrence in Volta Lake catches.     

Nodulation and nitrogen-fixation byHippophaë rhamnoides L. in the field

Summary 1. The extent of nodulation and nitrogen fixation by a population ofHippophaë rhamnoides bushes occurring on a sand dune system on the east coast of England has been studied.2. Nodules were found on all plants (the latter ranged from 3 to 16 years in age) and using the isotope N¹⁵ it was confirmed that these nodules fixed nitrogen. The nodules on the youngest plants were most active in fixation but because of the greater total nodule mass older plants fixed the largest quantities of nitrogen.3. Large increases in total nitrogen (i.e. soil plus plant nitrogen) occurred with increase in age of the plants, such nitrogen increases ranging from 27 kg per hectare per annum in the presence of bushes 0 to 3 years old to 179 kg per hectare per annum in the presence of bushes 13 to 16 years old.4. The N¹⁵-technique indicated that a proportion of the nitrogen accumulated was due to fixation byHippophaë but nitrogen contributions from other sources could not be ruled out.5. The levels of nitrate-nitrogen and ammonium-nitrogen in the soil underHippophaë showed a marked seasonal variation, increasing to a maximum in the winter and to a minimum in the summer. These levels were in general inversely related to the level of average monthly rainfall. Because of the low levels of combined nitrogen in the soil during the summer months it seems unlikely that combined nitrogen should markedly inhibit fixation in this situation.     

Nardo-Agrostion communities in the Krkonoše and West Carpathians Mts.

The montaneNardus-rich acidophilous meadows occurring in the Krkono?e and W. Carpathians Mts. were evaluated. They are classified intoNardo-Agrostion tenuis Sillinger 1933. Five associations were distinguished:Sileno-Nardetum, Homogyno-Nardetum, Hieracio Lachenalii-Nardetum, Phleo alpini-Nardetum, andRanunculo nemorosi-Nardetum, the first occuring in the Krkono?e Mts., the others in the W. Carpathians.     

Glycogen synthetase in the sea mussel Mytilus edulis L.—II. Seasonal changes in glycogen content and glycogen synthetase activity in the mantle tissue

• 1.1. The glycogen content of the mantle tissue reached a maximum in the summer (May–July) with levels of 41.0–53.5% of the dry tissue weight.
• 2.2. Seasonal changes in glycogen synthetase activity showed that the I-activity (independent of G6P) increased up to 10-fold in June as compared with December. The measured I-activity of glycogen synthetase was sufficient to account for the accumulation of mantle glycogen in the summer.
• 3.3. The I-activity of glycogen synthetase declined rapidly in July of each year. A possible role for the inhibition of glycogen synthetase by high levels of tissue glycogen is suggested.
• 4.4. The I-activity in the mantle tissue of mussels on the shore was higher than that for animals starved in the laboratory for 2–3 days. The differences were minimal in early May but increased markedly in late May–July. Starved mussels returned to the shore showed an increase in I-activity of glycogen synthetase.
• 5.5. Injection of 30 μmol glucose into the adductor muscle increased the concentration of glucose in the mantle fluid to 2.0–2.5 mM. A similar injection of 60 μ mol glucose resulted in a time-dependent increase in the I-activity of glycogen synthetase.
• 6.6. Injection of mussels with mammalian insulin or anti-insulin serum had no effect on the activity of glycogen synthetase. Our results are at variance with those of other workers who have used the mammalian hormone in molluscan studies (see Discussion).

     

Nucleosides and Nucleotides. 104. Radical and Palladium-Catalyzed Deoxygenation of the Allylic Alcohol Systems in the Sugar Moiety of Pyrimidine Nucleosides§,1

Abstract

New methods for the synthesis of 2′,3′-didehydro-2′,3′-dideoxy-2′ (and 3′)-methyl-5-methyluridines and 2′,3′-dideoxy-2′ (and 3′)-methylidene pyrimidine nucleosides have been developed from the corresponding 2′ (and 3′)-deoxy-2′ (and 3′)-methylidene pyrimidine nucleosides. Treatment of a 3′-deoxy-3′-methylidene-5-methyluridine derivative 8 with 1,1′-thiocarbonyldiimidazole gave the allylic rearranged 2′,3′-didehydro-2′,3′-dideoxy-3′-[(imidazol-1-yl)carbonylthiomethyl] derivative 24. On the other hand, reaction of 8 with methyloxalyl chloride afforded 2′-O-methyloxalyl ester 25. Radical deoxygenation of both 24 and 25 gave 26 exclusively. Palladium-catalyzed reduction of 2′,5′-di-O-acetyl-3′-deoxy-3′-methylidene-5-methyluridine (32) with triethylammonium formate as a hydride donor regioselectively afforded the 2′,3′-dideoxy-3′-methylidene derivative 35 and 2′,3′-didehydro-2′,3′-dideoxy-3′-methyl derivative 34 in a ratio of 95:5 in 78% yield. These reactions were used on the corresponding 2′-deoxy-2′-methylidene derivatives. An alternative synthesis of 2′,3′-dideoxy-2′-methylidene pyrimidine nucleosides (43, 52, and 54) was achieved from the corresponding 1-(3-deoxy-β-D-thero-pentofuranosyl)pyrimidines (44 and 45). The cytotoxicity against L1210 and KB cells and inhibitory activity of the pathogenicity of HIV-1 are also described     

Ethylene and cytokinin interaction in the morphogenesis of Pelargonium × hortorum L.H. Bailey in vitro

Pelargonium × hortorum ‘Grand Prix’ which is susceptible to leaf yellowing and ‘Bergpalais’ which is not susceptible to leaf yellowing were chosen for the experiments. Ethylene production and action as well as the associated morphological response of Pelargonium shoots grown in the presence of a precursor of ethylene biosynthesis 1-aminocyclopropane-1-carboxylic acid (ACC), ethylene inhibitors: α-aminooxyacetic acid (AOA) and silver nitrate (AgNO₃) and different cytokinins: (meta-topolin) (mT) or 6-benzylaminopurine (BAP) were studied. It was found that ‘Grand Prix’ was more sensitive to ethylene than ‘Bergpalais’ and it showed the leaf yellowing in response to 0.1 mg l^?1 ACC. Moreover, it was noted that ACC added separately or together with cytokinin influenced Pelargonium morphogenesis. Depending on the concentration of ACC (0.1–2.0 mg l^?1), it either stimulated or inhibited shoot and root formation as well as the growth of shoots and leaf blades. ACC-induced leaf yellowing in ‘Grand Prix’ was effectively inhibited by mT. In contrast, BAP did not enhance shoot quality. Simultaneously, the presence of mT in the medium resulted in up to a twofold increase in the ethylene production by ‘Grand Prix’ shoots throughout the culture period compared with the shoots growing on the BAP-medium. The inhibitor of ethylene action (AgNO₃) added with cytokinin prevented the yellowing of Pelargonium shoots, but simultaneously influenced the formation of mature shoots with limited long-term multiplication potential. The shoots of P. × hortorum ‘Grand Prix’ treated with AgNO₃ and mT emitted two- and sevenfold more ethylene after 11th and 21st day of culture compared with those treated with AgNO₃ and BAP. It is suggested that mT inhibits the early senescence of Pelargonium in vitro by decreasing its sensitivity to ethylene.     

Biotechnology education and the training of engineer-technologists in the St. Petersburg State Chemical–Pharmaceutical Academy and the State University of Technology and Design

Some facts about biotechnological education in St. Petersburg (Russia) are presented by authors at two different higher schools: the State Chemical–Pharmaceutical Academy and the State University of Technology and Design.     

The progamic phase, embryo and endosperm development in an intraspecific Tulipa gesneriana L. cross and in the incongruent interspecific cross T. gesneriana × T. agenensis DC.

 The development of the embryo and endosperm has been investigated in an intraspecific Tulipa gesneriana cross and in the incongruent cross T. gesneriana ×T. agenensis at intervals of 10 days, from 12 to 82 days after pollination (DAP). In both tulip crosses, the zygote gives rise to an apparently undifferentiated cell mass, the proembryonal cell mass, on which a suspensor then develops. Subsequently, a globular embryo is formed on top of the suspensor. This embryo finally elongates, giving rise to a spindle-shaped embryo. The cellular endosperm fills the whole embryo sac in mature seeds, except for a region immediately around the embryo. In both crosses, aberrant developments were found. In the intraspecific T. gesneriana cross, the pollen tubes did not open in a number of ovules. In other ovules, the pollen tubes seemed to have opened, but an embryo or endosperm was not found or only endosperm was observed. In the cross T. gesneriana ×T. agenensis, fewer pollen tubes entered the ovules than in the intraspecific T. gesneriana cross. The ovules with embryo and endosperm formation of the incongruent interspecific cross showed, in general, retarded development in comparison with the intraspecific T. gesneriana cross. The first globular embryos and spindle-shaped embryos were found at the later fixation dates and the relatively lower number of spindle-shaped embryos at 82 DAP had a shorter average length. The number of ovules with deformations in embryo and/or endosperm development was also higher in the cross T. gesneriana × T. agenensis in comparison with the intraspecific T. gesneriana cross. Between 87% and 100% of the ovules with embryo and endosperm development showed normal development in the intraspecific T. gesneriana cross, while in the incongruent interspecific cross, from 22 DAP, between 17% and 56% of the ovules showed normal development. Of those ovules with aberrations in embryo and/or endosperm formation, about 80% had a deformed endosperm, of which more than 50% also contained a deformed embryo. Embryos of the incongruent cross might be saved by the application of embryo rescue techniques. Received: 10 December 1996 / Revision accepted: 23 April 1997     

L. plantarum,L. fermentum,and B. breve Beads Modified the Intestinal Microbiota and Alleviated the Inflammatory Response in High-Fat Diet–Fed Mice

Probiotics and Antimicrobial Proteins - This paper aims to study the effects of compound microbe-based beads on changes in the intestinal microbiota and alleviation of high-fat (HF)...     

Flight of the honey bee. VIII. Functional elements and mechanics of the “flight motor” and the wing joint – one of the most complicated gear-mechanisms in the animal kingdom

The form and position of the sclerites and important parts of the thorax, as well as the insertion points of the flight muscles, are described in this study with the help of three-dimensional drawings and electron micrographs. Morphological studies are used for functional analysis of the wing joint and flight muscles, and a three-dimensional model of the wing joint of a honey bee is used to demonstrate the automatic forced guidance of the forewings during the upstroke and downstroke. Accepted: 4 February 1998     

Transmembrane orientation of α-helices in the thylakoid membrane and in the light-harvesting complex. A polarized infrared spectroscopy study

The structure and orientation of the major protein constituent of photosynthetic membranes in green plants, the chlorophyll $\text{a}\text{b}$ light-harvesting complex (LHC) have been investigated by ultraviolet circular dichroism (CD) and polarized infrared spectroscopies. The isolated purified LHC has been reconstituted into phosphatidylcholine vesicles and has been compared to the pea thylakoid membrane. The native orientation of the pigments in the LHC reconstituted in vesicles was characterized by monitoring the low-temperature polarized absorption and fluorescence spectra of reconstituted membranes. Conformational analysis of thylakoid and LHC indicate that a large proportion of the thylakoid protein is in the α-helical structure (56 ± 4%), while the LHC is for 44 ± 7% α-helical. By measuring the infrared dichroism of the amide absorption bands of air-dried oriented multilayers of thylakoids and LHC reconstituted in vesicles, we have estimated the degree of orientation of the α-helical chains with respect to the membrane normal. Infrared dichroism data demonstrate that transmembrane α-helices are present in both thylakoid and LHC with the α-helix axes tilted at less than 30° in LHC and 40° in thylakoid with respect to the membrane normal. In thylakoids, an orientation of the polar C=O ester groups of the lipids parallel to the membrane plane is detected. Our results are consistent with the existence of 3–5 transmembrane α-helical segments in the LHC molecules.     

Sunflower stem weevil and its larval parasitoids in native sunflowers: is parasitoid abundance and diversity greater in the U.S. Southwest?

Classical biological control programs often target a pest's region of origin as a likely source for new biological control agents. Here, we use this approach to search for biological control agents of the sunflower stem weevil (Cylindrocopturus adspersus LeConte), an economically important pest of commercial sunflower. We conducted surveys of weevil natural enemy diversity and abundance across a transect running from the northern Great Plains to the southwestern U.S. (the presumed area of endemism of annual sunflower species in the genus Helianthus). Accordingly, natural enemy diversity and abundance were expected to be greater in the southwestern U.S. C. adspersus and their larval parasitoids were collected from stems of four native sunflower species (Helianthus annuus, H. nuttallii, H. pauciflorus, and H. petiolaris) from 147 sites across eight states. Native H. annuus constituted the majority of the sunflower populations. Mean weevil densities were significantly higher in sunflower stalks that were larger in diameter. Mean weevil densities within sites did not differ across the range of longitudes and latitudes sampled. After accounting for the effects of stalk diameter and location, weevil densities did not differ among the four sunflower species nor did they differ as a function of elevation. C. adspersus in H. annuus and H. petiolaris were attacked by seven species of parasitoids. No parasitoids were found attacking C. adspersus in H. nuttallii or H. pauciflorus stalks. C. adspersus were twice as likely to be attacked by a parasitoid when feeding on H. petiolaris than H. annuus. Furthermore, the likelihood that C. adspersus would be parasitized decreased with increasing elevation and increasing stem diameters. All parasitoid species have been previously reported attacking C. adspersus larvae in cultivated sunflower. Species richness was less diverse in these collections than from previous studies of cultivated sunflower. Our findings suggest that the species of larval parasitoids attacking C. adspersus in native sunflowers have successfully made the transition to cultivated sunflower.     

Novel and recurrent mutations in the tyrosinase gene and the P gene in the German albino population

Albinism is a heterogeneous group of genetic disorders resulting from deficiencies in pigmentation. Clinically, it is divided into ocular (OA) and oculocutaneous albinism (OCA). OCA involves lack of pigment in the skin, hair, and eyes and results from mutations in the tyrosinase gene or in the P gene. OA mainly affects pigmentation in the visual system and may be a mild form of OCA or may be caused by other genetic defects. Clinical diagnosis of albinism type is difficult, because of the observed range of phenotypic variation. Thus, genetic analysis may be helpful with respect to a more accurate diagnosis. Here, we report the mutational profile, determined by genetic analysis of the tyrosinase and P genes, of a large German albino population. We have revealed a total of 42 distinct mutations, 19 of which are novel. Of the 74 unrelated patients screened, 32 (43%) had mutations in the tyrosinase gene, 16 (22%) had P gene mutations, and 26 (35%) patients had no detectable genetic abnormalities. This defines a population of albino patients who are tyrosinase-gene- and P-gene-negative and who thus may represent a good study group for searching for additional genes associated with albinism.