Altitudinal changes in the incidence of crassulacean acid metabolism in vascular epiphytes and related life forms in Papua New Guinea

Summary The occurrence of Crassulacean acid metabolism (CAM), as judged from w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C values, was investigated in epiphytes and some related plant species at a series of sites covering the approximate altitudinal range of epiphytes in Papua New Guinea. Comprehensive collections were made at each site and the occurrence of water storage tissue and blade thickness was also determined. Some 26% of epiphytic orchids from a lowland rainforest (2–300 m.a.s.l) showed w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C values typical of obligate CAM and possessed leaves thicker than 1 mm. A second group of orchids, mostly with succulent leaves, possessed intermediate w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C values between -23 and -26% and accounted for 25% of the total species number. Some species of this group may exhibit weak CAM or be facultative CAM plants. The remainder of the lowland rainforest species appeared to be C₃ plants with w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C values between -28 and -35%. and generally possessed thin leaves. Obligate CAM species of orchids from a lower montane rainforest (1175 m.a.s.l) comprised 26% of the species total and mostly possessed thick leaves. The remainder of the species were generally thin-leaved with w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C values between -26 and -35%. largely indicative of C₃ photosynthesis. Orchids with intermediate w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C values were not found in the lower montane rainforest. Obligate CAM appeared to be lacking in highland epiphytes from an upper montane rainforest and subalpine rainforest (2600–3600 m.a.s.l). However the fern, Microsorium cromwellii had a w471737329457681/xxlarge948.gif" alt="delta" align="BASELINE" BORDER="0">¹³C value of -21.28%. suggesting some measure of CAM activity. Other highland ferns and orchids showed more negative °¹³C values, up to-33%., typical of C₃ photosynthesis. The highland epiphytic orchids possessed a greater mean leaf thickness than their lowland C₃ counterparts due to the frequent occurrence of water storage tissue located on the adaxial side of the leaf. It is suggested that low daytime temperatures in the highland microhabitats is a major factor in explaining the absence of CAM. The increased frequency of water storage tissue in highland epiphytes may be an adaptation to periodic water stress events in the dry season and/or an adaptation to increased levels of UV light in the tropicalpine environment.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAcw5q276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3]Galß1-4Glc and GalNAcß1-4[NeuAcw5q276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3w5q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyllactose (NeuAcw5q276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3Galß1-4Glc) and 3w5q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyl-N-acetyllactosamine (NeuAcw5q276245v4/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3w5q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyl-N-acetyllactosamine was highly active whereas that formed with 3w5q276245v4/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-sialyllactose had only weak activity.     

Specificity towards oligomannoside and hybrid type glycans of the endo-β-N-acetylglucosaminidase B from the basidiomy ceteSporotrichum dimorphosporum

We have previously shown that an endo-w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-N-acetylglucosaminidase (EC 3.2.1.96) named w/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">Endo Bw/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0">, isolated from culture filtrates of the basidiomyceteSporotrichum dimorphosporum cleaves asialo-, and to some extent, monosialylated bi-antennary glycans of theN-acetyllactosamine type linked to the asparagine residue of peptide or protein moieties [Bouquelet S, Strecker G, Montreuil J, Spik G (1980) Biochimie 62:43–49]. In the present paper, the substrate specificity of the enzyme towards oligomannoside and hybrid type glycans has been analyzed. The results obtained indicate that ovalbumin glycopeptides containing four to seven mannose residues and bovine lactotransferrin glycopeptides containing four to nine mannose residues were completely hydrolyzed by the enzyme. The degree of cleavage was variable among hybrid type structures, since glycopeptides containing the following glycans: (Gal)₁(GlcNAc)₃(Man)₅(GlcNAc)₂; (GlcNAc)₃(Man)₅(GlcNAc)₂; (GlcNAc)₃(Man)₄(GlcNAc)₂ were not hydrolyzed by the enzyme while the percentage of hydrolysis of a glycopeptide containing (GlcNAc)₂(Man)₅(GlcNAc)₂ glycan reached 90%. The bovine lactotransferrin was partially deglycosylated (40%) in the absence of non-ionic detergent while native ovalbumin glycoprotein was not hydrolyzed by the enzyme.The oligomannoside-and theN-acetyllactosamine-type degrading activities present in the culture filtrates were not separated at any step of the purification procedure. Both activities were eluted as a single component with an apparent molecular mass of 89 kDa suggesting that they are located on the same enzyme molecule.Endo B represents a powerful tool for removing oligomannoside-andN-acetyllactosamine-type glycans fromN-glycopeptides andN-glycoproteins. Moreover, advantages in the use of Endo B in a soluble form as well as in an immobilized form result in its high activity and in its stability to heat denaturation and storage.Abbreviations Gal d-galactose - Man d-mannose - GlcNAc N-acetyl-d-glucosamine - Con A concanavalin A - Asn asparagine - GLC gas liquid chromatography - TLC thin layer chromatography - Endo endo-w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-N-acetylglucosaminidase - Endo B endo-w/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-N-acetylglucosaminidase isolated fromSporotrichum dimorphosporum - PBE polybuffer exchanger - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis     

Abnormal expression ofα-L-fucosidase in lymphoid cell lines of fucosidosis patients

Fucosidosis is an autosomal recessive lysosomal storage disease due to a deficiency ofw567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase activity in tissues and body fluids. Exponentially growing lymphoid cell cultures from four fucosidosis patients had 2.7-fold to 15.6-fold less extracellularw567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase protein and 28.8-fold to 144.0-fold less intracellularw567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase protein with negligible catalytic activity, compared to the mean of 19 control cultures. The percentage of totalw567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase protein released extracellularly by cultures from the four patients was 64 to 85%, compared to 35±9% for control cultures. Intracellular and extracellular enzyme forms in fucosidosis and control cell lines were glycoproteins containing polypeptide chains ofM _r=52,000. During a 1.5-hr pulse-label with³⁵S-methionine,w567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase was synthesized by control cells and two fucosidosis cell lines as an intracellular form withM _r=58,000. During a subsequent 21-hr chase with unlabeled methionine, mutant enzyme was almost entirely processed to an extracellular form withM _r=62,000. In contrast, only 25–30% of control enzyme was processed to an extracellular form (M _r=62,000), with the remainder retained intracellularly (M _r=60,000). In the other two fucosidosis cell lines,w567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase was synthesized as an intracellular form withM _r=56,000 that was processed to an extracellular form withM _r=60,000. In summary, the fucosidosis mutation(s) affected the catalytic activity, quantity, and extracellular release ofw567836/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-L-fucosidase as expressed by lymphoid cells.This work was funded by NIH Grants DK 32161 to R. A. DiCioccio and GM 28428 to J. K. Darby.     

An immunodominant site of γ-zein1 is in the region of tandem hexapeptide repeats

The immunochemical data from studies with polyclonal antisera to w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁, the 27 kD component of the maize prolamin, indicated that the region containing 8 tandem repeats of the sequence PPPVHL is an immunodominant site. In one case, the entire antibody repertoire of an antiserum recognized epitope(s) within this region. Three 17-mer oligopeptides corresponding to the predicted antigenic epitopes of w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁ were synthesized and reacted with three different anti-w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁ sera in order to map antigenic sites in the intact protein. These antisera yielded positive reactions with a 17-mer peptide (peptide 37), which was not in a hydrophilic maximum but derived from the repeat region. The same antisera gave little or no reaction with other peptides (peptides 38 and 39), both of which were in a hydrophilic maximum. In addition, an antiserum to peptide 37 reacted strongly with both the homologous antigen and the intact w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁. Peptide 37 also blocked the binding of antisera to w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁ in competition assays. Subsequently, the shorter 6-mer (peptide 82) and 12-mer (peptide 80) versions of peptide 37 were synthesized, and both reacted with anti-peptide 37 serum and also with each of the three anti-w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁ sera. In these reactions and in competition assays, the reactivity and the blocking ability increased in proportion to the length of the peptide. Based on these data, it was concluded that the repeat region of w477tv54581/xxlarge947.gif" alt="gamma" align="MIDDLE" BORDER="0">-zein₁ is the site of one or more continuous immunodominant epitopes. The data also suggest that the repeat region is exposed on the surface of the folded protein and probably occur as a mobile, random coil.     

Pollination biology of two species ofKielmeyera (Guttiferae) from Brazilian cerrado vegetation

The pollination biology and breeding systems ofKielmeyera coriacea andK. speciosa, two sympatric woody species common in the cerrado vegetation of C. Brazil, were studied. Both species have similar nectarless, polystemonous w4n894/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">Papaver-typew4n894/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> flowers which are visited by a similar spectrum of insects, though they bloom in different seasons and are thus phenologically isolated. Large carpenter bees seem to be the most important pollinators and these and other bees effect w4n894/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">buzz pollenw4n894/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> retrieval despite the fact that anthers are not poricidal. Both species ofKielmeyera possess strong xenogamous breeding systems. The presence of staminate flowers and andromonoecy inK. coriacea, as well as the longevity ofK. speciosa flowers are discussed as alternative strategies to improve pollination success and reproductive efficacy.     

Nitrite reduction in Bacteroids of Rhizobium “hedysari” strain HCNT 1

Ex planta, bacteroids of the sulla-symbiont Rhizobium w104718766/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">hedysariw104718766/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> strain HCNT 1 terminated reduction of nitrite at nitrous oxide irrespective of the presence or absence of acetylene. Nitrate was not reduced during the experimental period, but slight nitrate reductase activity occurred if incubation with nitrate was prolonged (up to 15 h). As was observed in free-living cells, exposure of the bacteroids to the metal chelator, diethyldithiocarbamate, prevented reduction of nitrite, indicating the presence of a copper-containing nitrite reductase. Pulses of 10–75 w104718766/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">M nitrite transiently impeded O₂ uptake in bacteroids, which resumed consumption of O₂ when the nitrite had been reduced. Exposure to >1.0 mM nitrite for 24h greatly inhibited nitrogenase activity (assayed as acetylene reduction activity) of bacteroids in planta. Exposure to the same concentrations of nitrite after 1h of incubation in the presence of acetylene almost completely stopped ongoing ethylene production in bacteroids of strain HCNT 1 extracted from nodules. Free cells of the non-nitrite-reducing R. w104718766/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">hedysariw104718766/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> strain CC 1335 were lacking in nitrogenase (acetylene-reduction) activity, whereas identically cultured (low-oxygen) strain HCNT 1 cells reduced both nitrite and acetylene.Abbreviations PMS phenazine methosulfate - DDC diethyldithiocarbamate     

Immobilization of enzymes on alumina by means of pyridoxal 5′-phosphate

A number of proteases have been immobilized on alumina in a two-step procedure: the first step converted them into semisynthetic phosphoproteins which, in the second step, spontaneously bonded to alumina through their phosphate function. The immobilized enzymes thus obtained showed the physical properties typical of the inorganic carrier and a high activity on low molecular weight substrates.     

2-Aminopurine and 5-bromouracil induce alleviation of type I restriction in Escherichia coli: Mismatches function as inducing signals?

Summary The EcoK restriction of unmodified phage w54535r2w63283/xxlarge955.gif" alt="lambda" align="BASELINE" BORDER="0"> is 1000-fold alleviated in Escherichia coli grown in the presence of base analogs 2-aminopurine (2AP) and 5-bromouracil (5BU). 2AP treatment of bacteria affects specificially the type I restriction systems (EcoA, EcoB, EcoD and EcoK) and does not influence type II (EcoRI) and type III (EcoP1) restriction. 2AP-induced alleviation of restriction occurs in bacteria which are deficient in the SOS response (recA and lexA) and mismatch repair (mutH, mutL and mutS) and can be distinguished from the alleviation of restriction observed in dam ^- strains. We suggest that mismatches induced by 2AP and 5BU may function as an inducing signal for the alleviation of restriction observed in the presence of base analogs.