Growth and photosynthetic response of the cyanobacterium Microcystis aeruginosa in relation to photoperiodicity and irradiance

Growth and photosynthetic characteristics, P _max (maximum light-saturated oxygen production rate) and (photosynthetic affinity), of Microcystis aeruginosa were studied in continuous cultures under a range of photoperiod lengths and growth irradiances. Microcystis showed a low specific maintenance rate constant and a high growth affinity for light (typical cyanobacterial features), but required a dark period to obtain maximum growth rate. P _max and per unit dry weight increased, as did pigment content, when less light became available. By regulation in and P _max (crucial in light-limiting and high-light conditions, respectively) this buoyant species can flourish in low light, but also in high-light environments which may arise when buoyancy is lost.The two different types of light conditions affected growth, and photosynthesis, in different ways. One needs thus to discriminate between photoperiod- and irradiance-limitation, which restricts the utility of simple algal growth models. It was emphasized that photosynthetic adaptation patterns of light-limited species may resemble short-term nutrient uptake kinetics of nutrient-limited organisms.With prior knowledge of the growth limitation, we were able to assess the growth rate of a natural population of Microcystis from its photosynthetic response and from data of laboratory cultures of a known physiological state.     

IL-33 induces antigen-specific IL-5+ T cells and promotes allergic-induced airway inflammation independent of IL-4

Type 2 cytokines (IL-4, IL-5, and IL-13) play a pivotal role in helminthic infection and allergic disorders. CD4(+) T cells which produce type 2 cytokines can be generated via IL-4-dependent and -independent pathways. Although the IL-4-dependent pathway is well documented, factors that drive IL-4-independent Th2 cell differentiation remain obscure. We report here that the new cytokine IL-33, in the presence of Ag, polarizes murine and human naive CD4(+) T cells into a population of T cells which produce mainly IL-5 but not IL-4. This polarization requires IL-1R-related molecule and MyD88 but not IL-4 or STAT6. The IL-33-induced T cell differentiation is also dependent on the phosphorylation of MAPKs and NF-kappaB but not the induction of GATA3 or T-bet. In vivo, ST2(-/-) mice developed attenuated airway inflammation and IL-5 production in a murine model of asthma. Conversely, IL-33 administration induced the IL-5-producing T cells and exacerbated allergen-induced airway inflammation in wild-type as well as IL-4(-/-) mice. Finally, adoptive transfer of IL-33-polarized IL-5(+)IL-4(-)T cells triggered airway inflammation in naive IL-4(-/-) mice. Thus, we demonstrate here that, in the presence of Ag, IL-33 induces IL-5-producing T cells and promotes airway inflammation independent of IL-4.     

First phylogenetic analysis of the tribe Oligaphorurini (Collembola: Onychiuridae) inferred from morphological data,with implications for generic classification

Oligaphorurini represent tribe of the subfamily Onychiurinae, which currently comprises 5 genera and 53 species. The present study evaluated the monophyly of Oligaphorurini genera. We investigated phylogenetic relationships among 39 species, representing all extant genera of Oligaphorurini. Both equal- and implied-weighting parsimony analyses were used in phylogenetic reconstruction. The cladistic analyses were based on comprehensive survey of adults’ morphological characters because specimens suitable for molecular studies were not available for the majority taxa. The phylogenetic analysis resulted in the recognition of a monophyletic Chribellphorura, and strongly supported non-monophyly of the previously recognized genera Archaphorura, Dimorphaphorura, Micraphorura, and Oligaphorura. The following new synonymy is recognized: Oligaphorura = Dimorphaphorura syn. nov., = Micraphorura syn. nov., = Archaphorura syn. nov. The general classification of Oligaphorurini is followed by the diagnoses of genera and key to the all known species.     

Gibberellin-photoaffinity labeling of wild oat (Avena fatua L.) aleurone protoplasts

Aleurone protoplasts of wild oat (Avena fatua L.), and subcellular fractions isolated from them, were photoaffinity labeled using the synthetic gibberellin (GA) derivative GA₄-17-yl-1-(1-thia)propan-3-ol-4-azido-5-[¹²⁵I]iodosalicylate. Labeled polypeptides were identified by electrophoresis under denaturing conditions followed by autoradiography. GA-photoaffinity labeling of both intact protoplasts and isolated subcellular fractions led to the covalent attachment of the reagent to many polypeptides. A 50 kD polypeptide in the soluble fraction of homogenates of aleurone protoplasts GA-photoaffinity labeled in vivo showed specific binding. The biologically active GA₁, GA₄ and GA₄-17-yl-1(1-thia)propan-3-ol-4-azidosalicylate completed for binding whereas the biologically inactive GA₈ and GA₃₄ did not. The GA-photoaffinity labeling characteristics of this polypeptide suggested that it might interact specifically with biologically active GAs in vivo. Attempts to detect specific GA-binding in in vitro GA-photoaffinity labeling experiments met with only limited success perhaps indicating the labile nature of specific binding observed in vivo. The potential of GA-photoaffinity labeling for identifying GA-binding proteins in aleurone and other GA-responsive tissues is discussed.Abbreviations azido IAA = 5-azido-7-[³H]indole-3-acetic acid - azido NPA = 5-azido-[3,6-³H]1-N-napthylpthalamic acid - BTP = 1,3-bis(Tris(hydroxymethyl)methylamino)-propane - GA₄-O-ASA = GA₄-17-yl-1-(1-thia)propane-3-ol-4-azidosalicylate - [¹²⁵I]GA₄-O-ASA = GA₄-17-yl-1-(1-thia)propan-3-ol-4-azido-5-[¹²⁵I]iodosalicylate - NPA = 1-Naphthylphthalmic acid - PAGE = Polyacrylamide gel electrophoresis - PMSF = phenylmethylsulfonyl fluoride - SDS = Sodium dodecyl sulphate - TLCK = L-1-Chloro-3-(4-tosylamido)-7-amino-2-heptanone-HCl     

Preparation and polypeptide composition of plasma membrane and other subcellular fractions from wild oat (Avena fatua) aleurone

Plasma membranes can be isolated from a variety of plant tissues by first preparing a post-mitochondrial membrane fraction enriched in plasma membranes, by differential centrifugation, and partitioning this on a dextran-polyethylene glycol two-phase system. With wild oat aleurone, however, we observed that differential centrifugation could not be used to produce a microsomal fraction enriched in plasma membrane. Approximately 70% of the plasma membrane in aleurone homogenates was pelleted by sequential centrifugation at 100 g× 10 min and 1000 g× 10 min. The remainder sedimented at 112 000 g× 1 h. All the material that was pelletable by centrifugation was, therefore, subjected to dextran-polyethylene glycol two-phase partitioning. The plasma membrane marker enzymes glucan synthase II (GSII, EC 2. 4. 1. 34) and UDP-glucose:sterol glucosyltransferase (SGT, EC 2. 4. 1.) were enriched in the upper phase, whereas cytochrome c oxidase activity (EC 1. 9. 3. 1), a mitochondrial marker enzyme, was depleted. The presence of endoplasmic reticulum (ER) and protein body membranes in the phase system was assessed by probing western blots, of SDS-PAGE separated proteins, with polyclonal antiserum either to binding protein (BiP, an ER marker) or to tonoplast intrinsic protein (TIP, a protein body membrane marker). BiP and TIP were present in the lower phase, but were not detected in the upper phase. In addition, the polypeptide patterns of material in the upper and lower phases were very different. These observations suggested that high purity aleurone plasma membrane had been isolated. Although the procedure for isolating plasma membranes was applicable to both aleurone protoplasts and layers, the polypeptide patterns of plasma membranes prepared from these sources were very different. The major protein components of wild oat aleurone were 7 S and 12 S storage globulins. These proteins were present in the lower phase, but not in the plasma membrane enriched upper phase, after aqueous two-phase partitioning. Differential centrifugation studies showed that it was necessary to homogenise aleurone in a buffer of pH 6. 0 or less if a soluble protein fraction, essentially devoid of storage globulins, was to be obtained. The use of these fractionation techniques is discussed in relation to photoaffinity labelling of gibberellin (GA)-binding proteins in aleurone.     

Possibilities of using the European bison (<Emphasis Type=Italic>Bison bonasus)</Emphasis> epididymal spermatozoa collected post-mortem for cryopreservation and artificial insemination: a pilot study

Background  

European bison is the largest mammal in Europe with the population of approximately 4000 individuals. However, there is no report of post-mortem spermatozoa collection and cryopreservation from this species and the aim of this study was to test if the epididymal spermatozoa collected post-mortem from European bison are suitable for cryopreservation and artificial insemination (AI).     

Molecular analysis of VCA1008: a putative phosphoporin of Vibrio cholerae

The PhoB/PhoR-dependent response to inorganic phosphate (Pi)-starvation in Vibrio cholerae O1 includes the expression of vc0719 for the response regulator PhoB, vca0033 for an alkaline phosphatase and vca1008 for an outer membrane protein (OMP). Sequences with high identity to these genes have been found in the genome of clinical and environmental strains, suggesting that the Pi-starvation response in V. cholerae is well conserved. VCA1008, an uncharacterized OMP involved in V. cholerae pathogenicity, presents sequence similarity to porins of Gram-negative bacteria such as phosphoporin PhoE from Escherichia coli . A three-dimensional model shows that VCA1008 is a 16-stranded pore-forming β-barrel protein that shares three of the four conserved lysine residues responsible for PhoE anionic specificity with PhoE. VCA1008 β-barrel apparently forms trimers that collapse into monomers by heating. Properties such as heat modifiability and resistance to denaturation by sodium dodecyl sulfate at lower temperatures permitted us to suggest that VCA1008 is a classical porin, more precisely, a phosphoporin due to its Pi starvation-induced PhoB-dependent expression, demonstrated by electrophoretic mobility shift assay and promoter fusion- lacZ assays.     

Identification of a nuclear antigen with molecular weight of 48,000 differentially expressed in tumour and normal cells

A non-histone protein with mol. wt of 48,000 differentially expressed in normal and tumour cells was identified using immunological criteria. Antibodies were raised against a component specific for Kirkman-Robbins hepatoma of mol. wt about 48,000 separated from hepatoma non-histone proteins by preparative electrophoresis in polyacrylamide gel. It was demonstrated by immunoblotting that Morris hepatoma 7777 and Ehrlich ascites cells share an antigenic non-histone protein with Kirman-Robbins hepatoma. Tumour cells when compared with normal cells, i.e. hamster and rat liver, are characterized by significant enrichment of this component. Intracellular distribution of the polypeptide with mol. wt 48,000 suggests that this component may be a structural protein the biosynthesis of which increases or the antigenic determinants of which change in tumour cells.