Thermal tolerance and recovery behaviour of Thorectes lusitanicus (Coleoptera,Geotrupidae)

1. Population differences in physiological responses are examined in Thorectes lusitanicus, an endemic Iberian dung beetle species, by submitting individuals of different populations to the same experimental and acclimation conditions. 2. An infrared thermography protocol was used, consisting of three assays: start of activity, cold response, and heat response. Individuals of 12 populations were studied and the comparative explanatory capacities of several environmental factors in relation to the observed inter‐population differences were examined. 3. The heating rate from chill coma to the beginning of activity was the variable with the highest discrimination power among the studied populations, accounting for 94% of the observed variance. Regarding the heat response, only six of the 16 thermal variables reached significance (inter‐population differences accounted for 52–74% in these six thermal parameters). 4. From the three considered environmental factors (Mediterranean climate, land cover, and trophic characteristics) only land cover characteristics remain statistically significant, affecting the cold response of individuals. 5. Thorectes lusitanicus is a species characterised by a high diversity of thermotolerance and recovery traits across populations with a low degree of association with broad environmental factors. Finally, it is suggested that the apterous character of this species could be a determinant factor explaining the high diversity of ecophysiological traits related to thermal stress tolerance and the recovery time.     

Improving efficiency of breeding for higher crop yield

Summary Exclusive selection for yield raises, the harvest index of self-pollinated crops with little or no gain in total bipmass. In addition to selection for yield, it is suggested that efficient breeding for higher yield requires simultaneous selection for yield's three major, genetically controlled physiological components. The following are needed: (1) a superior rate of biomass accumulation. (2) a superior rate of actual yield accumulation in order to acquire a high harvest index, and (3) a time to harvest maturity that is neither shorter nor longer than the duration of the growing season. That duration is provided by the environment, which is the fourth major determinant of yield. Simultaneous selection is required because genetically established interconnections among the three major physiological components cause: (a) a correlation between the harvest index and days to maturity that is usually negative; (b) a correlation between the harvest index and total biomass that is often negative, and (c) a correlation between biomass and days to maturity that is usually positive. All three physiological components and the correlations among them can be quantified by yield system analysis (YSA) of yield trials. An additive main effects and multiplicative interaction (AMMI) statistical analysis can separate and quantify the genotype × environment interaction (G × E) effect on yield and on each physiological component that is caused by each genotype and by the different environment of each yield trial. The use of yield trials to select parents which have the highest rates of accumulation of both biomass and yield, in addition to selecting for the G × E that is specifically adapted to the site can accelerate advance toward the highest potential yield at each geographical site. Higher yield for many sites will raise average regional yield. Higher yield for multiple regions and continents will raise average yield on a world-wide basis. Genetic and physiological bases for lack of indirect selection for biomass from exclusive selection for yield are explained.     

The Science in a Piece of Glass

Plant tropisms—their directional movement in response to stimuli—are a fundamental concept in plant science and excite students because they are the observable signs of life in plants. Unfortunately, the precollege teaching literature is full of tropism misconceptions. An inexpensive clock clinostat is invaluable for student gravitropism and phototropism experiments. It is also valuable for space biology experiments because a clinostat can mimic the microgravity of space.     

Xinnaokang improves cecal microbiota and lipid metabolism to target atherosclerosis

This study aims to explore the potential mechanisms of Xinnaokang in atherosclerosis treatment. Firstly, the active components of Xinnaokang were analysed by HPLC, which contains ginsenoside Rg1, puerarin, tanshinone, notoginsenoside R1, ammonium glycyrrhizate and glycyrrhizin. Network pharmacology analysis showed there were 145 common targets of Xinnaokang, including the chemical stress, lipid metabolite, lipopolysaccharide, molecules of bacterial origin, nuclear receptor and fluid shear stress pathways. Then, the animal experiment showed that Xinnaokang reduced the body weight and blood lipid levels of atherosclerotic mice. Vascular plaque formation was increased in atherosclerotic mice, which was markedly reversed by Xinnaokang. In addition, Xinnaokang reduced CAV-1 expression and increased ABCA1, SREBP-1 and LXR expressions in the vasculature. Xinnaokang promoted SREBP-2 and LDLR expressions in the liver but decreased IDOL and PCSK9 expressions, indicating that Xinnaokang regulated lipid transport-related protein expression. Cecal microbiota diversity was reduced in atherosclerotic mice but increased after Xinnaokang treatment. Xinnaokang treatment also improved gut microbiota communities by enriching Actinobacteria, Bifidobacteriales and Bifidobacteriaceae abundances. Metabolic profile showed that Xinnaokang significantly reduced homogentisate, phenylacetylglycine, alanine and methionine expressions in the liver of atherosclerotic mice. Xinnaokang effectively alleviated atherosclerosis, and this effect might be linked with the altered features of the liver metabolite profiles and cecal microbiota.     

Glycogen Metabolism in Aureobasidium Pullulans: A Glycogen Synthetase with Unusual Activation Properties

Abstract

Cultures of filamentous fungi that secrete significant amounts of exopolysaccharides are among the most difficult of fermentation fluids, presenting difficulties in the areas of aeration, agitation, mixing, and control that may in turn impact the physiology of the microorganism in an undesirable manner. The fungus Sclerotium glucanicum, which produces a potentially useful exopolysaccharide known as scleroglucan, illustrates many such difficulties. This review discusses in detail the range of physiological studies on the producing microorganism itself, including those concerning formation of “undesirable” byproducts, principally oxalate, but also, under certain conditions, other TCA cycle acids. In addition, the bioreactor technology in use for production of this type of biopolymer is discussed in relation to the difficulties such fluid types present. The potential of pneumatically agitated reactors for such production is evaluated, and the lack of fundamental studies on such reactors and on the hydrodynamics and mixing behavior of such complex fluids is pointed out.     

Anatomical and physiological changes of in vitro-propagated Vriesea imperialis (Bromeliaceae) in the function of sucrose and ventilated containers

Abstract

Under in vitro culture conditions, plants may present physiological and anatomical disorders, which can interfere negatively after ex vitro transfer. The aim of this investigation was to analyze the impacts of natural ventilation and sucrose supply on the anatomy and physiology of Vriesea imperialis. Plants previously grown in vitro were transferred to culture medium containing 0, 15, 30 or 45?g L^?1 sucrose. Three different culture container sealing systems were tested: lids with a green filter (81.35 gas exchanges per day), yellow filter (13.09 gas exchanges per day) or lids with a yellow filter covered with three layers of transparent polyvinylchloride (PVC) film (blocking fluent gas exchange). Sucrose concentrations influenced thickness, lignin and suberin deposition of exodermis cell wall. The modifications verified in leaves, such as higher density of stomata and trichome scales, showed that sucrose can induce osmotic stress in the plants. Photomixotrophic conditions, using containers with intermediate rate of gas exchange (yellow filter) and with 15–30?g L^?1 sucrose, produced an improvement in the growth traits and did not induce anatomical and physiological disturbances.     

Senescence in cut carnation flowers: Temporal and physiological relationships among water status, ethylene, abscisic acid and membrane permeability

Changes in water status, membrane permeability, ethylene production and levels of abscisic acid (ABA) were measured during senescence of cut carnation flowers ( Dianthus caryophyllus L. cv. White Sim) in order to clarify the temporal sequence of physiological events during this post-harvest period. Ethylene production and ABA content of the petal tissue rose essentially in parallel during natural senescence and after treatment of young flowers with exogenous ethylene, indicating that their syntheses are not widely separated in time. However, solute leakage, reflecting membrane deterioration, was apparent well before the natural rise in ethylene and ABA had begun. In addition, there were marked changes in water status of the tissue, including losses in water potential (ψ_w), and turgor (ψ_p), that preceded the rise in ABA and ethylene. As senescence progressed, ψ_w continued to decline, but ψ_p returned to normal levels. These temporal relationships were less well resolved when senescence of young flowers was induced by treatment with ethylene, presumably because the time-scale had been shortened. Thus changes in membrane permeability and an associated water stress in petal tissue appear to be earlier symptoms of flower senescence than the rises in ABA or ethylene. These observations support the contention that the climacteric-like rise in ethylene production is not the initial or primary event of senescence and that the rise in ABA titre may simply be a response to changes in water status.     

The agonistic adrenal: melatonin elicits female aggression via regulation of adrenal androgens

Classic findings have demonstrated an important role for sex steroids as regulators of aggression, but this relationship is lacking within some environmental contexts. In mammals and birds, the adrenal androgen dehydroepiandrosterone (DHEA), a non-gonadal precursor of biologically active steroids, has been linked to aggression. Although females, like males, use aggression when competing for limited resources, the mechanisms underlying female aggression remain understudied. Here, we propose a previously undescribed endocrine mechanism regulating female aggression via direct action of the pineal hormone melatonin on adrenal androgens. We examined this in a solitary hamster species, Phodopus sungorus, in which both sexes are highly territorial across the seasons, and display increased aggression concomitant with decreased serum levels of sex steroids in short ‘winter-like'' days. Short- but not long-day females had increased adrenal DHEA responsiveness co-occurring with morphological changes in the adrenal gland. Further, serum DHEA and total adrenal DHEA content were elevated in short days. Lastly, melatonin increased DHEA and aggression and stimulated DHEA release from cultured adrenals. Collectively, these findings demonstrate that DHEA is a key peripheral regulator of aggression and that melatonin coordinates a ‘seasonal switch’ from gonadal to adrenal regulation of aggression by direct action on the adrenal glands.     

Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking

ClC-K chloride channels are crucial for auditory transduction and urine concentration. Mutations in CLCNKB, the gene encoding the renal chloride channel hClC-Kb, cause Bartter syndrome type III, a human genetic condition characterized by polyuria, hypokalemia, and alkalosis. In recent years, several Bartter syndrome-associated mutations have been described that result in truncations of the intracellular carboxyl terminus of hClC-Kb. We here used a combination of whole-cell patch clamp, confocal imaging, co-immunoprecipitation, and surface biotinylation to study the functional consequences of a frequent CLCNKB mutation that creates a premature stop codon at Trp-610. We found that W610X leaves the association of hClC-Kb and the accessory subunit barttin unaffected, but impairs its regulation by barttin. W610X attenuates hClC-Kb surface membrane insertion. Moreover, W610X results in hClC-Kb channel opening in the absence of barttin and prevents further barttin-mediated activation. To describe how the carboxyl terminus modifies the regulation by barttin we used V166E rClC-K1. V166E rClC-K1 is active without barttin and exhibits prominent, barttin-regulated voltage-dependent gating. Electrophysiological characterization of truncated V166E rClC-K1 demonstrated that the distal carboxyl terminus is necessary for slow cooperative gating. Since barttin modifies this particular gating process, channels lacking the distal carboxyl-terminal domain are no longer regulated by the accessory subunit. Our results demonstrate that the carboxyl terminus of hClC-Kb is not part of the binding site for barttin, but functionally modifies the interplay with barttin. The loss-of-activation of truncated hClC-Kb channels in heterologous expression systems fully explains the reduced basolateral chloride conductance in affected kidneys and the clinical symptoms of Bartter syndrome patients.