The photobiont determines the pattern of photosynthetic activity within a single lichen thallus containing cyanobacterial and green algal sectors (photosymbiodeme)

Photosystem activity status of the green algal (Pseudocyphellaria lividofusca) and cyanobacterial (P. knightii) components of a photosymbiodeme were continuously monitored in the field over a period of 35 days. The photosymbiodeme grew on a Nothofagus menziesii tree at Lake Waikaremoana, Urewera National Park, North Island, New Zealand. Two Mini-PAM fluorometers were placed so that the chlorophyll a fluorescence, temperature and PPFD (photosynthetically active photon flux density) could be recorded every 30 min for green algal and cyanobacterial parts of the thallus. Microclimate conditions were also recorded with a datalogger. The study confirmed the already known ability of green algal lichens to reactivate from high humidity alone whilst cyanobacterial species need liquid water, here obtained from rainfall. The photosystems of P. lividofusca were activated on every day and positive ETR (relative electron transport rate) occurred on all but 3 days. Activation level depended on the overnight relative humidity. P. knightii was activated and had positive ETR on only 13 days when rainfall had occurred. Both species were mostly inactive above 12°C but differed at low temperatures. P. knightii showed no activation at very low temperatures, -2 to 0°C, since these only occurred on clear, rain-free nights. PPFD was always very low, mostly below 80 µmol m^-2 s^-1, and both species were inactive at higher PPFD. The three-dimensional structure of the thallus seemed to contribute to the hydration. The cyanobacterial sectors were more appressed to the trunk and needed substantial rainfall to rewet whereas the green algal lobes were more distant from the trunk and this probably caused more rapid desiccation as well as lower temperatures. It is suggested that the longer active periods for photosynthesis by P. lividofusca are balanced by several factors: first, depressed net photosynthesis at high thallus water contents after rainfall, a feature not shown by P. knightii; second, possible lower maximal net photosynthetic rates; and third, the possibility of greater respiratory rates when thalli have been hydrated by high relative humidity. There is little evidence for high PPFD differently affecting the photosymbiodeme components since sustained, high PPFD did not occur. It has been reported that the photosystems of cyanobacterial species from photosymbiodemes can reactivate at high relative humidity but the results obtained here suggest that it is not ecologically significant.     

Determination of selenium and iodine in human thyroids.

This study focuses on the determination of selenium and iodine in human thyroids. The glands were digested using nitric acid in a microwave oven. Selenium was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) using a new sample introduction system consisting of a reduction system coupled to a hydride generation nebulizer (DHGN). Iodine was determined by using the Sandell-Kolthoff procedure. The detections limits were 0.2 ng/mL and 0.3 ng/mL for the determination method of selenium and iodine, respectively. The amount of iodine in the whole gland was 3.44 +/- 1.11 microg/g. The lowest iodine level was 2.34 microg/g and the highest 5.21 microg/g. The lowest selenium concentration for a single sample was 505 +/- 51 ng/g and the highest 1495 +/- 204 ng/g depending on the fraction of the gland selected.     

Identity of plant,lichen and moss species connects with microbial abundance and soil functioning in maritime Antarctica

Background and aims

Plant breeding activities shape the rhizosphere microbiome but less is known about the relationship of both with the seed microbiome. We analyzed the composition of bacterial communities of seeds and rhizospheres of Styrian oil pumpkin genotypes in comparison to bulk soil to elucidate specific microbial signatures to support a concept involving plant-microbe interactions in breeding strategies.

Methods

The seed and rhizosphere microbiomes of 14 genotypes of oilseed pumpkin and relatives were analyzed using a 16S rRNA gene amplicon sequencing approach, which was assessed by bioinformatics and statistical methods.

Results

All analyzed microhabitats were characterized by diverse bacterial communities, but the relative proportions of phyla and the overall diversity was different. Seed microbiomes were characterized by the lowest diversity and dominant members of Enterobacteriaceae including potential pathogens (Erwinia, Pectobacterium). Potential plant-beneficial bacteria like Lysobacter, Paenibacillus and Lactococcus contributed to the microbial communities in significant abundances. Interestingly, strong genotype-specific microbiomes were detected for seeds but not for the rhizospheres.

Conclusions

Our study indicates a strong impact of the Cucurbita pepo genotype on the composition of the seed microbiome. This should be considered in breeding of new cultivars that are more capable of exploiting beneficial indigenous microbial communities.

     

Body mass estimation for †Cyonasua (Procyonidae,Carnivora) and related taxa based on postcranial skeleton

Procyonidae were the first northern placental carnivorans that reached the Neotropics. They are represented by two extinct genera: ?Cyonasua and ?Chapalmalania (late Miocene – early Pleistocene). Postcranial elements are only known for ?Cyonasua and related taxa (?Parahyaenodon argentinus and ?Tetraprothomo argentinus). To obtain highly reliable allometric equations for body mass estimations of fossil procyonids, we performed least squares regressions (multiple and bivariate lineal models) using 51 postcranial linear measurements. The extant sample included 124 taxa corresponding to nine families of Carnivora, with body mass data from the literature. We obtained about 63 equations from diverse combinations of postcranial measurements; 14 of them were selected using several reliability indexes as criteria. Our results show that body masses calculated for ?Cyonasua range between 12.63 and 28.45 kg, ?P. argentinus was estimated at 14.41 kg, while ?T. argentinus at 25.31 kg. Thus, the body mass of ?Cyonasua would have been at least twice as high as the mean of the extant procyonid Procyon cancrivorus. ?Cyonasua was probably able to fend off predators and quite capable of climbing slowly on thick-enough branches. Other palaeoecological and palaeobiological inferences are discussed.     

Skin unhairing proteases of Bacillus subtilis: production andpartial characterization

Proteases able to unhair sheep skins were produced from Bacillus subtilis. Protease activity was increased from 640 to 990 U/mL by using a fed-batch culture with glucose added sequentially up to 10 g/L. The crude enzyme prep-aration was mainly a mixture of metallo- and serine-proteases with optimal pH and temperature for protease activity at 7 and 50-55°C, respectively. At pH 8 and 30°C, protease activity of the crude enzyme was 33% of the maximal value and 97% of the original activity (900 U/mL) was retained after incubation for 4 hours.     

Distributional and ecophysiological study on the Antarctic lichens species pair <Emphasis Type="Italic">Usnea antarctica</Emphasis>/<Emphasis Type="Italic">Usnea aurantiaco</Emphasis>-<Emphasis Type="Italic">atra</Emphasis>

The factors that control lichen distribution in Antarctica are still not well understood, and in this investigation we focused on the distribution, local and continental, and gas exchange of a species pair, closely related lichens with differing reproductive strategies, Usnea aurantiaco-atra (fertile) and Usnea antarctica (sterile, sorediate). The local distributions of these species were recorded along an altitudinal gradient of nearly 300 m at South Bay, Livingston Island, and microclimate was also recorded over 1 year. The photosynthetic responses to temperature, light and thallus water content were determined under controlled conditions in the laboratory. The species were almost identical in their photosynthetic profiles. Locally, on Livingston Island, U. antarctica was confined to low altitude sites which were warmer and drier, whilst U. aurantiaco-atra was present at all altitudes. This contrasts with its distribution across Antarctica where U. antarctica grows 9° latitude further south than U. aurantiaco-atra. Temperature appears not to be the main controller of distribution in these species, but dryness of habitat, which will influence length of activity periods, may be important.     

Glucose 6-Phosphate and Fructose 1,6-Bisphosphate Can Be Used as ATP-Regenerating Systems by Cerebellum Ca2+-Transport ATPase

Abstract : In this work, it is shown that the Ca²⁺-transport ATPase found in the microsomal fraction of the cerebellum can use both glucose 6-phosphate/hexokinase and fructose 1,6-bisphosphate/phosphofructokinase as ATP-regenerating systems. The vesicles derived from the cerebellum were able to accumulate Ca²⁺ in a medium containing ADP when either glucose 6-phosphate and hexokinase or fructose 1,6-bisphosphate and phosphofructokinase were added to the medium. There was no Ca²⁺ uptake if one of these components was omitted from the medium. The transport of Ca²⁺ was associated with the cleavage of sugar phosphate. The maximal amount of Ca²⁺ accumulated by the vesicles with the fructose 1,6-bisphosphate system was larger than that measured either with glucose 6-phosphate or with a low ATP concentration and phosphoenolpyruvate/pyruvate kinase. The Ca²⁺ uptake supported by glucose 6-phosphate was inhibited by glucose, but not by fructose 6-phosphate. In contrast, the Ca²⁺ uptake supported by fructose 1,6-bisphosphate was inhibited by fructose 6-phosphate, but not by glucose. Thapsigargin, a specific SERCA inhibitor, impaired the transport of Ca²⁺ sustained by either glucose 6-phosphate or fructose 1,6-bisphosphate. It is proposed that the use of glucose 6-phosphate and fructose 1,6-bisphosphate as an ATP-regenerating system by the cerebellum Ca²⁺-ATPase may represent a salvage route used at early stages of ischemia ; this could be used to energize the Ca²⁺ transport, avoiding the deleterious effects derived from the cellular acidosis promoted by lactic acid.     

Hybrid larch heterosis: for which traits and under which genetic control?

RCD1 is a member of the plant-specific SRO protein family. Several SRO genes have been functionally identified in the regulation of abiotic stresses in Arabidopsis and other plant species. However, the function of SROs is largely unknown in apple (Malus×domestica). In this study, six MdSRO-encoding genes were isolated, categorized into two types and mapped to six chromosomes. The phylogenetic analysis demonstrated that the sequences of the AtSRO and MdSRO proteins are highly conserved. Subsequently, expression analysis showed that MdSRO genes had different expression profiles in different tissues and in response to various stresses. Finally, MdRCD1 was isolated for functional identification. The results showed that resistance to oxidation stress in apple calli was enhanced by MdRCD1 overexpression and weakened by MdRCD1 suppression. MdRCD1 also played a crucial role in the regulation of ROS homeostasis in transgenic apple calli and Arabidopsis. Ectopic expression of MdRCD1 significantly enhanced resistance to salt and oxidative stresses in transgenic lines. In addition, MdRCD1 also enhanced drought tolerance due to its influence on stomatal opening. Based on these results, we conclude that MdRCD1 is an important regulator in abiotic stress response.