Complementation analysis of the inorganic carbon concentrating mechanism of Chlamydomonas reinhardtii

Summary Six independently isolated mutants of Chlamydomonas reinhardtii that require elevated CO₂ for photoautotrophic growth were tested by complementation analysis. These mutants are likely to be defective in some aspect of the algal concentrating mechanism for inorganic carbon as they exhibit CO₂ fixation and inorganic carbon accumulation properties different from the wild-type. Four of the six mutants defined a single complementation group and appear to be defective in an intracellular carbonic anhydrase. The other two mutations represent two additional complementation groups.Abbreviations HS high salt medium which has 13 mM phosphate at pH 6.8 - HSA high salt plus 36 mM acetate medium - YA high salt medium with 4 g yeast extract per L and 36mM acetate - Arg arginine - cia^- CO₂ accumulation mutants that cannot grow on low CO₂ - C_i inorganic carbon (CO₂+HCO _- ³ ) - CA carbonic anhydrase - mt mating type Supported in part by the McKnight Foundation and by NSF grant PCM 8005917 and published as journal article 11924 from the Michigan State Agriculatural Experiment Station     

Enhancement of Oxygen-Evolution in Photosystem II-Phycobilisome Particles from Porphyridium cruentum

Oxygen-evolving photosystem II-phycobilisome particles froma red alga were inhibited 50–80% by aging, dilution, lowpH and salt-washing. Bovine serum albumin, and dithiothreitolwere found to stimulate activity in all but salt-washed particles.CaCl₂ and MnCl₂ partially restored activity lost after agingor dilution. ¹Current address: Waksman Institute of Microbiology, RutgersUniversity, Piscataway, New Jersey 08854-0759, U.S.A. (Received October 5, 1985; Accepted March 31, 1986)     

Three related centromere proteins are absent from the inactive centromere of a stable isodicentric chromosome

We developed an aqueous spreading procedure that permits simultaneous analysis of human chromosomes by Q-banding and indirect immunofluorescence. Using this methodology and anticentromere antibodies from an autoimmune patient we compared the active and inactive centromeres of an isodicentric X chromosome. We show that a family of structurally related human centromere proteins (CENP-A, CENP-B, and CENP-C) is detectable only at the active centromere. These antigens therefore may be regarded both as morphological and functional markers for active centromeres.     

Release of AMP and adenosine from rat heart mitochondria

Release of AMP and adenosine from rat heart mitochondria was studied. The rate of appearance of extramitochondrial adenosine was independent of the extramitochondrial phosphate concentration between 5 and 20 mM. In the absence of exogenous, respiratory substrates or in the presence of glutamate/malate plus rotenone, the rate of appearance of adenosine was relatively low when phosphate was not added. The appearance of extramitochondrial AMP + adenosine was found to be directly proportional to the extra-mitochondrial phosphate concentration. Zn2+ (10 mM) decreased the rate of adenosine appearance by 90% and increased the rate of AMP appearance 6-fold. The mitochondrial preparations dephosphorylated exogenous AMP; this activity was inhibited by 10 mM Zn2+. We conclude that the adenosine appearing in the extramitochondrial space was not due to a direct release from the matrix, but instead was due to adenine nucleotide release with subsequent conversion to adenosine in the extramitochondrial space.     

Beneficial effect of S-adenosyl-L-methionine in lead intoxication. Another approach to clinical therapy

Five patients with chronic lead intoxication were treated with S-adenosyl-L-methionine (12 mg/kg body weight, daily), given intravenously, over a period of 22 days. A significant recovery of erythrocytic ALA-D was observed in all cases, after therapy. Blood lead content significantly pathologic at the beginning of SAM administration, rapidly decreased within 24-48 h of initiating treatment, reaching nearly control values at the end of the trial. A good correlation between recovery of ALA-D activity and decreased concentration of lead in RBC was found. GSH content in blood was diminished in lead poisoned patients, increasing to normal levels after SAM administration. Other biochemical parameters such as Deaminase activity in RBC, ALA, PBG, porphyrins and lead in urine and serum gamma-GT were measured, showing no important deviations from control values before, during or after treatment. Both biochemical and clinical improvement was observed, indicating that SAM therapy is beneficial in the treatment of lead intoxication. No untoward signs were observed. The mechanism of action of SAM is not yet clear; however, a chelating effect could be excluded, and very likely its action can be attributed to glutathione availability.     

Green-backed herons (Butorides striatus) possibly using a lure and using apparent bait

Zusammenfassung In Burkina Faso ließ ein Mangrovereiher offensichtlich gezielt eine Asclepiadaceen-Blüte aus 20 cm Höhe auf die Wasseroberfläche fallen und verharrte danach einige Sekunden mit halb-gestrecktem Hals. Bei einer weiteren Beobachtung in Niger plazierte ein Mangrovereiher einen kleinen Gegenstand auf der Wasseroberfläche. Bevor der Gegenstand mit dem Wind außer Reichweite trieb, holte ihn der Reiher und legte ihn auf der Luvseite wieder auf der Wasseroberfläche ab. Der Vorgang wiederholte sich mehrere Male, dabei gelang es dem Reiher, einen Fisch zu erbeuten, der allerdings wieder entkam. Anderntags setzte an derselben Stelle ein Mangrovereiher in gleicher Weise offensichtlich einen Käfer ein. Ähnliche Beobachtungen werden kurz diskutiert.     

Cyclic nucleotide phosphodiesterases in somatic and germ cells of mouse seminiferous tubules

The distribution of phosphodiesterase forms in somatic and germ cells, and their variations during testicular development and germ cell differentiation have been investigated. Seminiferous tubules from immature mice and Sertoli cells in culture possessed two enzyme activities which were comparable to forms described for different tissues and species: (a) a calcium-calmodulin-dependent enzyme with high affinity for guanosine 3',5'-(cyclic)-monophosphate (cGMP), and (b) a calcium-calmodulin-independent enzyme with high affinity for adenosine 3',5'-(cyclic)-monophosphate (cAMP) the activity of which increased in cultured Sertoli cells after treatment with FSH or dibutyryl cAMP. Seminiferous tubules from adult animals and germ cells at the meiotic and post-meiotic stage of differentiation possessed two enzyme forms that could be distinguished from those present in somatic cells of the seminiferous tubules: (a) a calcium-calmodulin-dependent form with high affinity for both cAMP and cGMP, similar to forms described in other tissues from different species, and (b) a calcium-calmodulin-independent phosphodiesterase with high affinity for cAMP and present only in post-meiotic cells, previously identified also in germ cells of the rat.     

Ammonium uptake in Rhodopseudomonas capsulata

Investigations of the uptake of ammonium (NH ₄ ⁺ ) by Rhodopseudomonas capsulata B100 supported the presence of an NH ₄ ⁺ transport system. Experimentally NH ₄ ⁺ was determined by electrode or indophenol assay and saturation kinetics were observed with two apparent K _m's of 1.7 M and 11.1 M (pH 6.8, 30°) and a V _max at saturation of 50–60 nmol/min·mg protein. The optimum pH and temperature were 7.0 and 33° C, respectively. The Q₁₀ quotient was calculated to be 1.9 at 100 M NH ₄ ⁺ , indicating enzymatic involvement. In contrast to the wild type, B100, excretion of NH ₄ ⁺ , not uptake, was observed in a glutamine auxotroph, R. capsulata G29, which is derepressed for nitrogenase and lacks glutamine synthetase activity. G29R1, a revertant of G29, also took up NH ₄ ⁺ at the same rate as wild type and had fully restored glutamine synthetase activity. Partially restored derivatives, G29R5 and G29R6, grew more slowly than wild type on NH ₄ ⁺ as the nitrogen source, remained derepressed for nitrogenase in the presence of NH ₄ ⁺ , and displayed rates of NH ₄ ⁺ uptake in proportion to their glutamine synthetase activity. Ammonium uptake and glutamine synthetase activity were also restored in R. capsulata G29 exconjugants which had received the plasmid pPS25, containing the R. capsulata glutamine synthetase structural gene. These data suggest that NH ₄ ⁺ transport is tightly coupled to assimilation.Abbreviations used CHES cyclohexylaminoethanesulfonic acid - GS glutamine synthetase - SDS sodium dodecylsulfate