Application of the imidate procedure to α-d-galactosyltion

Using the imidate procedure, 2,3,4,6-tetra-O-benzyl-1-O-(N-methylacetimidoyl)-β-d-galactopyranose was condensed with various monosaccharides to provide, in good yield and with high stereoselectivity, α-linked disaccharides.     

Protein secondary structure of the isolated photosystem II reaction center and conformational changes studied by Fourier transform infrared spectroscopy.

The secondary structure of the photosystem II (PSII) reaction center isolated from pea chloroplasts has been characterized by Fourier transform infrared (FTIR) spectroscopy. Spectra were recorded in aqueous buffers containing H2O or D2O; the detergent present for most measurements was dodecyl maltoside. The broad amide I and amide II bands were analyzed by using second-derivative and deconvolution procedures. Absorption bands were assigned to the presence of alpha-helices, beta-sheets, turns, or random structure. Quantitative analysis revealed that this complex contained a high proportion of alpha-helices (67%) and some antiparallel beta-sheets (9%) and turns (11%). An irreversible decrease in the intensity of the band associated with the alpha-helices occurs upon exposure of the isolated PSII reaction center to bright illumination. This loss of alpha-helical content gave rise to an increase in other secondary structures, particularly beta-sheets. After similar pretreatment with light, sodium dodecyl sulfate polyacrylamide gel electrophoresis reveals lower mobility and solubility of constituent D1 and D2 polypeptides of the PSII reaction center. Some degradation of these polypeptides also occurs. In contrast, there is no change in the mobility of the two subunits of cytochrome b559. In the absence of illumination, the PSII reaction center exchanged into dodecyl maltoside shows good thermal stability as compared with samples in Triton X-100. Only at a temperature of about 60 degrees C do spectral changes take place that are indicative of denaturation.     

The effects of sediment type on growth rate and shell allometry in the soft shelled clam Mya arenaria L

Hatchery-reared juvenile Mya arenaria L. were grown for 11 wk in replicated gravel, sand, mud, and pearl net treatments under flow-through sea-water conditions in Maine. Analyses of variance showed significant differences between sediment treatments for final shell length, dry meat weight, chondrophore growth increment, and percent shell weight. Growth of juvenile M. arenaria was more rapid in fine sediments than in coarse sediments or nets.Regression slopes of shell length-shell height and shell length-shell depth varied significantly between sediment treatments. Slower-growing clams from nets and gravel were more globose than clams from sand or mud treatments. Clams grown in sand were longer and narrower than those from mud. Differences in growth rates and shell form were attributed primarily to the physical properties of the substrata, and their effects on the scope for growth of M. arenaria.     

Bacterial productivity in the water column and sediments of the Georgia (USA) coastal zone: Estimates via direct counting and parallel measurement of thymidine incorporation

Three methods of estimating bacterial productivity were compared using parallel samples of Atlantic Ocean water (within 0.25–15 km of the Georgia coast). The frequency-of-dividing cells (FDC) method and the [³H]thymidine incorporation method gave results which were strongly correlated (r=0.97), but the FDC estimates were always higher (X2 to X7) than the [³H]thymidine estimates. Estimates of bacterial productivity ranged from 2–4×10⁸ cells·l^–1·h^–1 at 0.25 km from shore to 1–9×10⁷cells·l^–1·h^–1 at 15 km. A method involving incubation of 3-m filtrates and direct counting gave results that could not be easily translated into estimates of bacterial productivity. Application of the FDC method to sediment samples gave high productivity estimates, which could be not reconciled with productivity estimates based on sediment oxygen uptake.     

Taxonomy of the genusGlycine,domestication and uses of soybeans

The genusGlycine has had a stormy taxonomic history. Recent studies of herbarium specimens and cytological and morphological analyses of living collections, coupled with chemotaxonomic investigations, have made it necessary to revise the genus. In the first part of this paper the current taxonomic status of the genusGlycine is reviewed. The soybean was domesticated in China. It is unfortunate that the literature concerned with the antiquity and historical development of the soybean is obscured by legends and myths. In the second section of the paper, the archeological, historical, agricultural and botanical literature is summarized in order to present all the known evidence as to when, where and by whom the soybean was domesticated. The soybean is the world’s premier source of dietary vegetable oil and is nutritionally an excellent and inexpensive source of protein for use either as human food or animal feed. In addition, the soybean has numerous industrial uses. In the last section of this paper the traditional uses of fermented and nonfermented soybeans in the East as well as the high-technology-developed uses of soybeans in the West are summarized.     

Seed coat variation in Glycine Willd. subgenus Glycine (Leguminosae) by SEM

Seed of the genusGlycine Willd. typically exhibits a muriculate appearance resulting from adherence to the true seed coat of the perisperm or inner pod wall layer. Thickened cell walls of the perisperm superimpose a reticulate network on the seed coat, the type of network ranging from alveolate to stellate depending on the shape of the perisperm cells. Tubercles distributed at intervals give the seed its roughened appearance. Seed lacking an attached perisperm appears smooth and shiny. Seed morphology of 62 collections representing the six species of the subgenusGlycine is examined in detail to elucidate inter-and intraspecific variability. Seed perisperm pattern appears to be characteristic for each species, but there are exceptions.Glycine canescens F. J. Herrn. andG. clandestina Willd. seeds possess a reticulate network and tubercles of irregular shape, the perisperm appearing granular inG. clandestina. Seeds ofG. latrobeana (Meissn.) Benth. andG. tabacina (Labill.) Benth. lack a distinct network and have stellate tubercles; the perisperm is granular inG. latrobeana and some plants ofG. tabacina. A few collections ofG. clandestina approachG. tabacina in seed appearance.Glycine tomentella Hayata seeds exhibit a regularly alveolate arrangement, while those ofG. falcata Benth. lack a perisperm layer altogether. Variation in seed coat within a species can usually be linked to differences in chromosome number or some aspect of gross morphology. Diploid collections ofG. tomentella (2n = 40) exhibit recognizable differences in seed morphology compared with tetraploids (2n = 80), coincident with other striking dissimilarities in gross morphology. An incompletely attached perisperm is accompanied by aneuploidy in severalG. tomentella accessions, while other 78 and 38 chromosome aneuploids produce normal seeds.     

The lack of mitogenic response of neuraminidase-treated and untreated human blood lymphocytes to divalent, hexavalent, or insoluble Helix pomatia a hemagglutinin

The mitogenic effects on human blood lymphocytes of Helix pomatia A hemagglutinin (HP) were measured by assaying incorporation of [¹⁴C]thymidine into cellular DNA. This highly purified lectin binds to human lymphocytes, treated with neuraminidase, but not to untreated lymphocytes. HP, which is hexavalent in its native form, totally failed to induce DNA synthesis in neuraminidase-treated as well as in untreated cells. Divalent HP, prepared by partial reduction and alkylation, and HP insolubilized by coupling to nylon sheets, also lacked mitogenicity. Control experiments indicated that neuraminidase-treated lymphocytes responded well to mitogenic lectins such as PHA. The lack of mitogenicity of HP was in contrast to the effects of soy bean agglutinin (SBA), which resembled HP in regard to carbohydrate specificity and ability to bind to neuraminidase-treated lymphocytes only. SBA was strongly mitogenic for neuraminidase-treated lymphocytes. The mitogenic effects of SBA were not inhibited by including varying doses of HP in the incubation mixtures. The results indicate that binding of lectin to carbohydrate receptors on the lymphocyte surface is not by itself sufficient to trigger DNA-synthesis.