Carbon isotope composition of N2-fixing and N-fertilized legumes along an elevational gradient

Dinitrogen-fixing legumes are frequently assumed to be less water-use efficient than plants utilizing soil mineral N, because of the high respiratory requirements for driving N₂ fixation. However, since respiration is assumed not to discriminate against ¹³C, any differences in water-use efficiency exclusively due to respiration should not be apparent in carbon isotope discrimination () values. Our objective was to determine if the source of N (N₂ fixation versus soil N) had any effect on of field-grown grain legumes grown at different elevations. Four legume species, Glycine max, Phaseolus lunatus, P. vulgaris, and Vigna unguiculata, were grown on five field sites spanning a 633 m elevational gradient on the island of Maui, Hawaii. The legumes were either inoculated with a mixture of three effective strains of rhizobia or fertilized weekly with urea at 100 kg N ha^-1 in an attempt to completely suppress symbiotic N₂-fixing activity. In 14 of 20 analyses of stover and 12 of 15 analyses of seed values were significantly higher (p=0.10) in the inoculated plants than the N-fertilized plants. Nitrogen concentrations were generally higher in the fertilized treatments than the inoculated treatments. The different values obtained depending on N-source may have implications in using as an indicator of water-use efficiency or yield potential of legumes.     

Interferon antibodies in patients with infectious diseases

Interferons (IFNs) are generally recognized as the most important therapeutic agent in some infectious diseases such as chronic hepatitis B and C. Since the early clinical trials it was documented that the therapeutic use of IFNs could be complicated by the development of antibodies able to neutralize or to bind to the IFN molecule. After several years of research it is now widely accepted that the presence of circulating anti-IFN antibodies may affect the response to IFN. Here we summarize what is currently know on the clinical significance of antibodies to IFN in IFN-treated viral diseases patients.     

棘豆属刺垫棘豆亚属(豆科)的订正

1971年,N.Ulzijkhutag根据采自阿拉善戈壁(=Bordzon-Go-bi)的标本(1970-07-29,V.I.Grubov,N.Ulzijkhutag et G.Tserendalzhid,无号)发表新种Oxytrops grubovii,并以此建立新组Oxytropis subgen.Traganthoxytropis sect.Monan-thos;1987年,G.P.Yakovlev将O.grubovii归入海绵豆属Spongiocarpella;1988年,张振万同意N.Ulzijkhutag的意见,并根据刺垫棘豆之龙骨瓣无喙等特征将Ulzijkhutag的刺     

A novel approach to the analysis of the initiation of embryo development in gramineae

An in vivo model system to study the initiation of embryo development is presented. From the so-called Salmon system of wheat (alloplasmic lines with a 1BL-1RS chromosome translocation), three completely isogenic and homozygous lines were produced by selection for uniformity in about 20 selfing/backcross generations as well as between sublines of doubled haploids. The line (aestivum)-Salmon is male fertile and sexual. The lines (caudata)-Salmon and (kotschyi)-Salmon are male sterile and have a parthenogenetic capacity of about 90%. The expression of nuclear-cytoplasmic male sterility is different for the two parthenogenetic lines. The initiation of autonomous embryo development at defined developmental stages of the ovaries and the maximum degree of parthenogenesis are identical in both parthenogenetic lines as proved by the auxin test and progeny analyses. The protein patterns from ovary extracts of the three isogenic lines were identical for more than 200 spots of 2-D polyacrylamide gels, confirming their homogeneity. However, one protein (P 115.1) was found 3 days before and during anthesis only in ovaries of the parthenogenetic lines. It seems to be involved in the initiation of parthenogenesis.     

Heterogeneity of heparan sulfate proteoglycans synthesized by PYS-2 cells

Antibodies to the basement membrane proteoglycan produced by the EHS tumor were used to immunoprecipitate [35S]sulfate-labeled protoglycans produced by PYS-2 cells. The immunoprecipitated proteoglycans were subsequently fractionated by CsCl density gradient centrifugation and Sepharose CL-4B chromatography. The culture medium contained a low-density proteoglycan eluting from Sepharose CL-4B at Kav = 0.18, containing heparan sulfate side chains of Mr = 35-40,000. The medium also contained a high-density proteoglycan eluting from Sepharose CL-4B at Kav = 0.23, containing heparan sulfate side chains of Mr = 30,000. The corresponding proteoglycans of the cell layer were all smaller than those in the medium. Since the antibodies used to precipitate those proteoglycans were directed against the protein core, this suggests that these proteoglycans share common antigenic features, and may be derived from a common precursor which undergoes modification by the removal of protein segments and a portion of each heparan sulfate chain.     

Mutant hemoglobin stability depends upon location and nature of single point mutation

The temperature dependence of the rates of heme release from the beta subunits of methemoglobin A and 5 beta mutant methemoglobins has been determined. The rates were largest for two hemoglobins with mutations distal to heme, previously known to be unstable. The other 3 mutants also released heme faster than A. These hemoglobins, with single point mutations at the alpha 1/beta 2 interface, were previously thought to be stable. The low reported yields of the 5 mutant proteins covaries with the relative rates of heme release from the met species.     

Carbon metabolism and gas exchange in leaves of Zea mays L.

The aim of this work was to investigate the mechanism of formation of triose phosphates and 3-phosphoglycerate during photosynthetic induction in leaves of Zea mays. Simultaneous measurements of gas exchange, chlorophyll a fluorescence and metabolite contents of maize leaves were made. Leaves illuminated in the absence of CO₂ showed a build-up of triose phosphates during the first 2 min of illumination which was comparable to the build-up observed in the presence of CO₂. Isolated mesophyll protoplasts, which lack the Calvin cycle, also showed a build-up of triose phosphates upon illumination. Leaves contained amounts of phosphoglycerate mutase and enolase adequate to account for the formation of triose phosphates and 3-phosphoglycerate from intermediates of the C₄ cycle and their precursors.     

Human cytomegalovirus induces a cellular deoxyguanosine kinase, also interacting with Acyclovir

Abstract A cytosol deoxyguanosine kinase (dGK) is induced in either growing or human cytomegalovirus (HCMV, AD169)-infected human fibroblasts (HEF). Data obtained from polyacrylamide gel electrophoresis, heat inactivation and phosphorylation kinetic experiments proved that these dGKs are identical, but completely differ from HCMV-induced thymidine kinase (TK) or deoxycytidine kinase (dCK). In contrast to TK or dCK, only dGK interacts with Acyclovir ( K _i = 590 μ M). It is suggested that dGK is an important enzyme determining the antiviral activity of Acyclovir.     

Cell free synthesis of some storage protein subunits by polyribosomes and RNA isolated from developing seeds of pea (Pisum sativum L.)

Polyribosomes which have template activity in the wheat germ system have been isolated from developing pea seeds. Some of the translation products have identical mobilities to the vicilin and legumin subunits by SDS-PAGE. Certain products were specifically immunoprecipitated with antisera prepared against purified vicilin and legumin fractions. Various RNA fractions including poly A-rich RNA have also been isolated from polyribosomes and shown to direct the synthesis of polyripeptides whose properties are similar to the storage protein subunits. The results are discussed in relationship to other investigations with seed storage protein biosynthesis in vitro.Abbreviations DTT dithiothreitol - SDS-PAGE SDS-polyacrylamide gel electrophoresis - TCA tricarboxylic acid