长白猪、枫泾猪和它们的杂种后代Ag—NOR的研究

4头枫泾猪,3头长白猪和5头长白×枫泾杂一代的NOR平均数分别为3.88、2和2.95。33头长白×枫泾杂二代猪(杂一代互交后代),其中7头黑猪的NOR众数为4,平均数为3.85;9头白猪的NOR众数为2,平均数为2.25;14头白猪的NOR众数为3,平均数为2.86;3头花猪的NOR众数分别为4.3、3,平均数为3.65、3.00和3.08。根据长白、枫泾和长白×枫泾杂一代和杂二代的NOR数目的区别和变化,NOR的遗传符合孟德尔定律。根据NOR数目与毛色的高度相关,提出了决定猪的黑白毛色的基因位于8号染色体并与NOR连锁的假设。猪的毛色除由位于8号染色体上的毛色基因所决定外,还应受其它基因位点的影响。     

Metal concentrations in surficial sediments from hypersaline lakes,Australia

A major drawback to the use in aquaculture of members of the Eubranchiopoda from temporary pool environments is that their eggs do not hatch readily. An investigation of the factors influencing the hatching of eggs of the fairy shrimpStreptocephalus macrourus, showed that light was the only factor of those investigated that was obligatory for hatching. It was found that eggs which had not been desiccated hatched successfully in the presence of absence of adults, while those which had been desiccated showed a block in hatching initially, although this block deteriorated with time and after approximately two months the eggs which had been desiccated showed a similar hatching success to that of the non-desiccated eggs. Exposure of eggs to extremes of heat or cold before incubation did not influence the hatching success of the eggs significantly, but the temperature at which incubation took place was important. The optimal range lay between 14 °C and 20 °C. Eggs hatched and nauplii survived at dissolved oxygen tensions of below 0.5 mg 1^–1     

Photocleavage of myosin subfragment 1 by vanadate

The heavy chain of myosin's subfragment 1 (S1) was cleaved at two distinct sites (termed V1 and V2) after irradiation with UV light in the presence of millimolar concentrations of vanadate and in the absence of nucleotides or divalent metals. The V1 site cleavage appeared to be identical with the previously described active site cleavage at serine-180, which is effected by irradiation of a photomodified form of the S1-MgADP-Vi complex [Cremo, C. R., Grammer, J. C., & Yount, R. G. (1989) J. Biol. Chem. 264, 6608-6011]. The V2 site was cleaved specifically, without cleavage at the V1 site, first by formation of the light-stable S1-Co2+ADP-Vi complex at the active site [Grammer, J. C., Cremo, C. R., & Yount, R. G. (1988) Biochemistry 27, 8408-8415] and then by irradiation in the presence of millimolar vanadate. By gel electrophoresis, the V2 site was localized to a region about 20 kDa from the COOH terminus of the S1 heavy chain. From the results of tryptic digestion experiments, the COOH-terminal V2 cleavage peptide appeared to contain lysine-636 in the linker region between the 50- and 20-kDa tryptic peptides of the heavy chain. This site appeared to be the same site cleaved by irradiation of S1 (not complexed with Co2+ADP-Vi) in the presence of millimolar vanadate as previously described [Mocz, G. (1989) Eur. J. Biochem. 179, 373-378]. Cleavage at the V2 site was inhibited by Co2+ but was not significantly affected by the presence of nucleotides or Mg2+ ions. Tris buffer significantly inhibited V2 cleavage. From the results of UV-visible absorption, 51V NMR, and frozen-solution EPR spectral experiments, it was concluded that irradiation with UV light reduced vanadate +5 to the +4 oxidation state, which was then protected from rapid reoxidation by O2 by complexation with the Tris buffer. The relatively stable reduced form or forms of vanadium were not competent to cleave S1 at either the V1 or the V2 site. 51V NMR titration experiments indicated that a tetrameric species of vanadium preferentially bound to S1 and to the S1-MgADP-Vi complex, whereas no binding of either the monomeric or dimeric species could be detected. These results suggest that the vanadate tetramer was responsible for the photocleavage of S1 which occurred at both the V1 and V2 sites in the absence of nucleotides or divalent metals.     

ULTRASTRUCTURE OF GLANDULAR TRICHOMES OF LEAVES OF NICOTIANA TABACUM L., cv XANTHI

Electron microscopy confirms previous light microscope observations that tobacco leaf trichomes are glandular and that there are two different types. Both the tall trichome (multicellular stalk, unicellular or multicellular head) and the short trichome (unicellular stalk; multicellular head) exhibit characteristics common to gland cells—a dense cytoplasm, numerous mitochondria, and little vacuolation. The tall trichome contains structurally well developed chloroplasts and an elaborate network of endoplasmic reticulum. The short trichome contains undifferentiated plastids and endoplasmic reticulum which parallels the nucleus and plasmalemma. Few dictyosomes are seen either in the short trichome or in the tall trichome. The short trichome appears to undergo structural changes concurrently with the appearance of secretory product within the cells. The most noticeable change is the formation of the extraplasmic space between the cell wall and the plasmalemma. Electron dense secretory product is observed between the plasmalemma and the cell wall and within the intercellular spaces.     

Etude comparee des proprietes physico-chimiques des mannanes de neuf levures

In order to correlate and compare the antigenic relationships observed between nine yeast strains, we have studied their major antigenic determinant represented by the mannans. This material is a constituent of their cell.The compounds that we have isolated are, in reality, glycopeptides. All their polysaccharide fractions consist of mannose only — except for those of the compounds that we have isolated of R. glutinis and C. lipolytica. All these polysaccharides have very close ramified structures; the only one that seems to be very different is that of R. glutinis, and this is in agreement with the antigenic properties of that yeast.The peptidic fractions of these glycopeptides are rich in threonine, serine and aspartic acid and it is very likely that these amino acids make the link with the polysaccharide fraction. The quantity of these amino acids seem to be affected by the conditions of culture of the yeasts, but not their presence or absence.     

The genetics of cell-mediated lympholysis.

The role of HLA antigens in the generation of cytotoxic cells in CML has been investigated. Cytotoxic effector cells were generated in MLC among HLA-A or HLA-A and HLA-B disparate, HLA-D identical siblings, and among HLA-A and HLA-B disparate, MLC identical (%RR less than or equal to 2 3.6) unrelated individual. The data indicate that HLA-D differences and poliferative MLC responses as measured by 3H-thymidine incorporation are not requisite for the in vitro generation of cytotoxic cells and suggest the existence of a CML-S locus (loci) distinct from HLA-A, HLA-B and HLA-D. The degree of cytotoxicity generated in a proliferative versus a "nonproliferative" MLC was comparable. In addition, these studies demonstrate that antigens other than the currently definable HLA-A, HLA-B, HLA-C, and HLA-D can serve as target determinants in cell-mediated lympholysis.     

Levans. II. Light-scattering and sedimentation data of Streptococcus salivarius Levan in water.

The molecular weights and radii of gyration of Streptococcus salivarius levan fractions were obtained from light-scattering measurements in water. Sedimentation coefficients and partial specific volumes of the fractions were also obtained. Double logarithmic plots of [η] versus M?_w and S⁰ versus M?_w yielded slopes having values of 0.17 and 0.62, respectively. The data and various calculated parameters show that levan from Streptococcus salivarius is highly branched and behaves hydrodynamically as a compact particle of spherical symmetry.