Energy Transfer from Phycobilisomes to Photosystems of Nostoc flagelliforme Born. et Flah. During the Rewetting Course and Its Physiological Significance

During the non-frost season, the condensation of dew makes Nostocflagelliforme Born. et Flah., a highly drought-tolerant terrestrial cyanobacterium, frequently undergo rehydration-dehydration.Rehydration begins in the dark at night. After rewetting in the dark, photochemical activity and the structure of photosystem (PS) Ⅱ were not recovered at all; the structure of PSⅠ, energy transfer in phycobilisomes, and energy transfer from phycobilisomes to PSⅠ were recovered within 5 min, as in the light. The recovery of energy transfer from phycobilisomes to PSⅡ was light dependent and energy transfer from phycobilisomes to PSⅡ was only partially recovered in the dark. These results suggest that the two-trigger control (water and light) of photosynthetic recovery may make N. flagelliforme avoid unnecessary energy consumption and, at the same time, the partial recovery of energy transfer from phycobilisomes to PSⅡ in the dark could help N. flagelliforme accumulate more photosynthetic products during the transient period of rehydrationdehydration.     

Activity and impulsive action are controlled by different genetic and environmental factors

Both impulsivity in operant tasks and locomotor activity in a novel open field are known to predict the development of addiction-related behavior in rodents. In this study, we investigated to what extent impulsivity in the five-choice serial reaction time task and various measures of novelty exploration are controlled by shared genetic and environmental factors in 12 different inbred mouse strains. No genetic correlation was observed between the level of impulsivity and levels of activity, a low correlation was observed with traditional measures of anxiety-like behavior (impulsive strains tend to be less anxious) and a highly significant correlation was found between impulsivity and specific aspects of movement. Furthermore, we found that impulsivity and all measures of novelty exploration were under control of different environmental factors. Interestingly, in the dorsal medial prefrontal cortex, a brain region involved in impulsivity and activity in novelty exploration tests; these behavioral measures correlated with the expression of different genes (respectively, Frzb , Snx5, BC056474 and the previously identified Glo1 ). Taken together, our study shows that impulsivity and activity in novelty exploration tests are genetically and environmentally distinct, suggesting that mouse models of these behaviors provide complementary insights into the development of substance abuse disorder.     

Acclimation to temperature and irradiance modulates PSII charge recombination

Acclimation of wild type and the chlorina F2 mutant of barley to either high light or low temperature results in a 2- to 3-fold increase in non-photochemical quenching which occurred independently of either energy-dependent quenching (qE), xanthophyll cycle-mediated antenna quenching or state transitions. Results of in vivo thermoluminescence measurements used to address this conundrum indicated that excitation pressure regulates the temperature gap for S(2)Q(B)(-) and S(2)Q(A)(-) charge recombinations within photosystem II reaction centers. This is discussed in terms of photoprotection through non-radiative charge recombination.     

Diurnal variation of the delta 13C of pine needle respired CO2 evolved in darkness

The delta 13C of pine needle CO2 evolved in darkness (delta 13Cr) for slash pine trees (Pinus elliottii) was determined by placing recently collected pine needles in darkness and collecting respired CO2 over a short time period (<15 min). Delta 13Cr measurements were made over several 24 h periods to test the hypothesis that significant variation in delta 13Cr would be observed during a diurnal cycle. The delta 13Cr measurements from the 24 h time series trials showed a consistent midday 13C-enrichment (5-10 per thousand) relative to bulk biomass. The delta 13Cr values became more 13C-depleted at night and following shading, and approached bulk-biomass delta 13C values by dawn. The effect of night-time respired 13C-enriched CO2 on the delta 13C value of the remaining assimilate is shown to be minimal (13C depleted by 0.22 per thousand) under field conditions for P. elliottii needles.     

Thioredoxin-dependent regulation of photosynthetic glyceraldehyde-3-phosphate dehydrogenase: autonomous vs. CP12-dependent mechanisms

Regulation of the Calvin–Benson cycle under varying light/dark conditions is a common property of oxygenic photosynthetic organisms and photosynthetic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is one of the targets of this complex regulatory system. In cyanobacteria and most algae, photosynthetic GAPDH is a homotetramer of GapA subunits which do not contain regulatory domains. In these organisms, dark-inhibition of the Calvin–Benson cycle involves the formation of a kinetically inhibited supramolecular complex between GAPDH, the regulatory peptide CP12 and phosphoribulokinase. Conditions prevailing in the dark, i.e. oxidation of thioredoxins and low NADP(H)/NAD(H) ratio promote aggregation. Although this regulatory system has been inherited in higher plants, these phototrophs contain in addition a second type of GAPDH subunits (GapB) resulting from the fusion of GapA with the C-terminal half of CP12. Heterotetrameric A₂B₂-GAPDH constitutes the major photosynthetic GAPDH isoform of higher plants chloroplasts and coexists with CP12 and A₄-GAPDH. GapB subunits of A₂B₂-GAPDH have inherited from CP12 a regulatory domain (CTE for C-terminal extension) which makes the enzyme sensitive to thioredoxins and pyridine nucleotides, resembling the GAPDH/CP12/PRK system. The two systems are similar in other respects: oxidizing conditions and low NADP(H)/NAD(H) ratios promote aggregation of A₂B₂-GAPDH into strongly inactivated A₈B₈-GAPDH hexadecamers, and both CP12 and CTE specifically affect the NADPH-dependent activity of GAPDH. The alternative, lower activity with NADH is always unaffected. Based on the crystal structure of spinach A₄-GAPDH and the analysis of site-specific mutants, a model of the autonomous (CP12-independent) regulatory mechanism of A₂B₂-GAPDH is proposed. Both CP12 and CTE seem to regulate different photosynthetic GAPDH isoforms according to a common and ancient molecular mechanism.     

Nutritional value of brine shrimp cysts as a factitious food for Orius laevigatus (Heteroptera: Anthocoridae)

Decapsulated cysts of the brine shrimp Artemia franciscana were assessed as a factitious food for rearing the anthocorid predator Orius laevigatus. Developmental and reproductive traits of O. laevigatus reared for a single generation on A. franciscana from three geographical locations or on gamma-irradiated eggs of the Mediterranean flour moth Ephestia kuehniella were compared. There was no effect of diet on nymphal survival but nymphal period on E. kuehniella eggs (12.2 days) was 0.7-1.6 days shorter than on the Artemia diets. The predator developed 0.5-1 day faster on cysts from San Francisco Bay (USA) than on cysts from Great Salt Lake (USA) or Macau (Brazil). Fecundity on brine shrimp cysts from different locations was similar to that on flour moth eggs (142-187 eggs/female). The biochemical composition of decapsulated cysts from San Francisco Bay was compared with that of E. kuehniella eggs. Depending on the type of analysis, Artemia cysts contained higher or similar amounts of protein as compared with E. kuehniella eggs, but amino acid patterns were generally similar. Flour moth eggs were almost three times richer in fatty acids than brine shrimp cysts, with some marked differences in fatty acid profiles. Because nutrient imbalances in a diet may be expressed only after several generations of rearing, the predator was cultured for three consecutive generations on A. franciscana cysts from San Francisco Bay. In the third generation on brine shrimp cysts, nymphs took 18% longer to develop, and adults were shorted-lived and about 60% less fecund than those maintained on E. kuehniella eggs. Brine shrimp cysts may be used as a supplement in the mass production of O. laevigatus but may not be a suitable food for long-term culturing of the predator.     

Comparison of Hemolymph and Holotissues of Different Species of Insects as Diet Components forin VitroRearing ofTrichogramma galloiZucchi andT. pretiosumRiley

The aim of this work was to compare pupal holotissues (Diatraea saccharalis, Anticarsia gemmatalis,andBombyx mori) and larval hemolymph of several moth species (Helicoverpa zeaandBombyx mori) commonly produced in Brazilian laboratories as components of artificial diets forin vitrorearing ofTrichogramma galloiandTrichogramma pretiosum.Diets based on larval hemolymph ofH. zeaproduced the best development of both natural enemies, although a diet with pupal holotissues ofB. moriallowed full development ofT. pretiosum.Amino acid analysis showed qualitative differences among the insect derivates and eggs of the natural and alternative hosts, but with a quantitative similarity. Electrophoretic analysis resulting in a diverse protein-stained bands evidenced the qualitative differences among these components.     

Rearing and mass production of the predatory mite Phytoseiulus persimilis

A method for mass rearing Phytoseiulus persimilis Athias-Henriot is proposed. This predacious mite is maintained in rearing units composed of cylinders which contain leaves heavily infested with Tetranychus urticae Koch. The bottom of the cylinders is made of gauze. Fresh cylinders with prey are placed at regular intervals on tops of older ones and predators will migrate upward. Empty cylinders at the undermost position are removed. Production takes place in a controlled-environment room under optimal temperature and humidity. Harvesting of predators in bran which can be easily disseminated over the crops is also described. A method of estimating the conserved populations is proposed.

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Résumé Une méthode d'élevage de Phytoseiulus persimilis permettant une production continue est proposée. La multiplication des auxiliaires a lieu dans des unités d'élevage formées de cylindres contenant des feuilles fortement chargées en Tetranychus urticae et renouvelées régulièrement par juxtaposition d'un nouveau cylindre. La production a lieu dans une salle climatisée ce qui permet de maintenir des conditions de température et d'hygrométrie optimum pour le développement de P. persimilis. La récolte des prédateurs dans du son, support facile à disséminer dans les cultures est également décrite, une méthode d'estimation des populations de conservation est également proposée.

     

The domestication of Amazonia before European conquest

During the twentieth century, Amazonia was widely regarded as relatively pristine nature, little impacted by human history. This view remains popular despite mounting evidence of substantial human influence over millennial scales across the region. Here, we review the evidence of an anthropogenic Amazonia in response to claims of sparse populations across broad portions of the region. Amazonia was a major centre of crop domestication, with at least 83 native species containing populations domesticated to some degree. Plant domestication occurs in domesticated landscapes, including highly modified Amazonian dark earths (ADEs) associated with large settled populations and that may cover greater than 0.1% of the region. Populations and food production expanded rapidly within land management systems in the mid-Holocene, and complex societies expanded in resource-rich areas creating domesticated landscapes with profound impacts on local and regional ecology. ADE food production projections support estimates of at least eight million people in 1492. By this time, highly diverse regional systems had developed across Amazonia where subsistence resources were created with plant and landscape domestication, including earthworks. This review argues that the Amazonian anthrome was no less socio-culturally diverse or populous than other tropical forested areas of the world prior to European conquest.