Dehydration-induced changes in spectral reflectance indices and chlorophyll fluorescence of Antarctic lichens with different thallus color,and intrathalline photobiont

In this study, we investigated responses of the Photochemical Reflectance Index (PRI), and Normalized Difference Vegetation Index (NDVI) to gradual dehydration of several Antarctic lichen species (chlorolichens: Xanthoria elegans, Rhizoplaca melanophthalma, Physconia muscigena, cyanolichen: Leptogium puberulum), and a Nostoc commune colony from fully wet to a dry state. The gradual loss of physiological activity during dehydration was evaluated by chlorophyll fluorescence parameters. The experimental lichen species differed in thallus color, and intrathalline photobiont. In the species that did not exhibit color change with desiccation (X. elegans), NDVI and PRI were more or less constant (mean of 0.25, ??0.36, respectively) throughout a wide range of thallus hydration status showing a linear relation to relative water content (RWC). In contrast, the species with apparent species-specific color change during dehydration exhibited a curvilinear relation of NDVI and PRI to RWC. PRI decreased (R. melanophthalma, L. puberulum), increased (N. commune) or showed a polyphasic response (P. muscigena) with desiccation. Except for X. elegans, a curvilinear relation was found between the NDVI response to RWC in all species indicating the potential of combined ground research and remote sensing spectral data analyses in polar regions dominated by lichen flora. The chlorophyll fluorescence data recorded during dehydration (RWC decreased from 100 to 0%) revealed a polyphasic species-specific response of variable fluorescence measured at steady state—F_s, effective quantum yield of photosystem II (Φ_PSII), and non-photochemical quenching (qN). Full hydration caused an inhibition of Φ_PSII in N. commune while other species remained unaffected. The dehydration-dependent fall in Φ_PSII was species-specific, starting at an RWC range of 22–32%. Critical RWC for Φ_PSII was around 5–10%. Desiccation led to a species-specific polyphasic decrease in F_s and an increase in qN indicating the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts and N. commune cells. In this study, the spectral reflectance and chlorophyll fluorescence data are discussed in relation to the potential of ecophysiological processes in Antarctic lichens, their resistance to desiccation and survival in Antarctic vegetation oases.     

ATP and ADP hydrolysis in cell membranes from rat myometrium

Extracellular nucleotides affect female reproductive functions, fertilization, and pregnancy. The aim of this study was to investigate biochemical characteristics of ATP and ADP hydrolysis and identify E-NTPDases in myometrial cell membranes from Wistar albino rats. The apparent K _m values were 506.4?±?62.1 and 638.8?±?31.3?μM, with a calculated V _max (app) of 3,973.0?±?279.5 and 2,853.9?±?79.8?nmol/min/mg for ATP and ADP, respectively. The enzyme activity described here has common properties characteristic for NTPDases: divalent cation dependence; alkaline pH optimum for both substrates, insensitivity to some of classical ATPase inhibitors (ouabain, oligomycine, theophylline, levamisole) and significant inhibition by suramine and high concentration of sodium azides (5?mM). According to similar apparent K_m values for both substrates, the ATP/ADP hydrolysis ratio, and Chevillard competition plot, NTPDase1 is dominant ATP/ADP hydrolyzing enzyme in myometrial cell membranes. RT-PCR analysis revealed expression of three members of ectonucleoside triphosphate diphosphohydrolase family (NTPDase 1, 2, and 8) in rat uterus. These findings may further elucidate the role of NTPDases and ATP in reproductive physiology.     

The heterosis estimates for growth and survival traits in sterlet and Siberian sturgeon purebreds and hybrids

The aim of the present study was to estimate and compare the growth and survival traits of the hybrids and purebreds produced by crossing the Siberian sturgeon (Acipenser baerii) (S) and sterlet (Acipenser ruthenus) (St) in order to determine the heterosis effect in the F1 generation. We compared the breeding conditions, mean body weight (BW) and cumulative survival in the artificially produced hybrid crosses of sterlet and Siberian sturgeon with respect to their pure parental species in indoor and outdoor aquaculture systems at different developmental stages. Fertilization and hatching rates were found to be significantly higher in S × S purebred compared to St × S hybrid. The highest values of BW were recorded in St × S hybrid (557.54 ± 179.7 g) on 862 days post-hatch (dph) while the highest cumulative survival was recorded in S × S purebred (14.3%). The recorded cumulative survival and mean BW was significantly lower in St × St purebred. The highest positive heterosis was recorded for mean BW of St × S hybrid (51.3% on 862 dph) throughout the sampling points. The studied sturgeon hybrids had higher mean BW compared to St × St purebred under suboptimal rearing conditions. Although there was no clear demonstration of the superiority in performance of reciprocal hybrids over purebreds, the St × S hybrid can be used for achieving better productivity in aquaculture systems.     

Reconstructing a puzzle: existence of cyanophages containing both photosystem‐I and photosystem‐II gene suites inferred from oceanic metagenomic datasets

Cyanobacteria play a key role in marine photosynthesis, which contributes to the global carbon cycle and to the world oxygen supply. Genes encoding the photosystem‐II (PSII) reaction centre are found in many cyanophage genomes, and it was suggested that the horizontal transfer of these genes might be involved in increasing phage fitness. Recently, evidence for the existence of phages carrying Photosystem‐I (PSI) genes was also reported. Here, using a combination of different marine metagenomic datasets and a unique crossing of the datasets, we now describe the finding of phages that, as in plants and cyanobacteria, contain both PSII and PSI genes. In addition, these phages also contain NADH dehydrogenase genes. The presence of modified PSII and PSI genes in the same viral entities in combination with electron transfer proteins like NAD(P)H dehydrogenase (NDH‐1) strongly points to a role in perturbation of the cyanobacterial host photosynthetic electron flow. We therefore suggest that, depending on the physiological condition of the infected cyanobacterial host, the viruses may use different options to maximize survival. The modified PSI may alternate between functioning with PSII in linear electron transfer and contributing to the production of both NADPH and ATP or functioning independently of PSII in cyclic mode via the NDH‐1 complex and thus producing only ATP.     

Performance differences among ex situ native-provenance collections of Pinus radiata D. Don. 1: potential for infusion into breeding populations in Australia and New Zealand

Growth and form traits from a series of three provenance trials of Pinus radiata D. Don planted in New Zealand and Australia were analysed at age 9 years from planting. The trials included selections from three mainland California natural populations—A?o Nuevo, Monterey and Cambria. Monterey and Cambria performed better than A?o Nuevo at two New Zealand sites, but Monterey and A?o Nuevo were almost identical in growth, whereas Cambria grew less vigorously at the Australian site. We detected significant provenance differences for diameter at breast height (DBH) growth and stem straightness across countries (p < 0.001). Estimated heritability for DBH ranged from 0.19 to 0.26 within sites, while heritability estimates for stem straightness and branching frequency ranged from 0.10 to 0.24. Estimated type B genetic correlations for DBH were always higher between the two trials in New Zealand trials than between pairs of trials in New Zealand and the Australian site. The genetic coefficient of variation (CV_A) for DBH was around 8–10% compared to ca. 5% for the current breeding population. These results suggested that there is appreciable genetic variation in the native populations, and infusion of these materials would increase the genetic variation in current breeding populations. Ten unrelated parents ranked above control seedlots from the older open-pollinated seed orchard stock for DBH growth and would be potential candidates for infusion. The promising performance of the Cambria material is an important result because the genetic base of the present Australian and New Zealand plantations is principally derived from A?o Nuevo and Monterey.     

Morphing of the phylogeographic lineages of the Balkan alpine newts (Ichthyosaura alpestris, Caudata, Salamandridae): in situ morphological diversification

Numerous alpine newt (Ichthyosaura alpestris) populations from the Balkans, representing all the previously established phylogeographic lineages, were studied for variations in various morphological characteristics (body size and shape, skull qualitative traits and number of trunk vertebrae). Here, we present a decoupling of morphological and mtDNA phylogeographic substructuring in the alpine newt on the Balkan Peninsula. In sharp contrast to other European newts (Triturus spp., Lissotriton spp.), the vast majority of morphological variation in the alpine newt is concentrated at the population level indicating an in situ morphological diversification. We found that the rate of morphological change is similar to the rate of mtDNA change. We hypothesize that the alpine newts are characterized by non-adaptive morphological evolution.     

A successful crayfish invader is capable of facultative parthenogenesis: a novel reproductive mode in decapod crustaceans

Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the "tens rule" which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group.