A comparison of ten digestive enzymes reveals a lack of chitinase in a phasmid and the loss of two β-glucanases in a mantid

In all developmental stages, the phasmid Peruphasma schultei (Conle & Hennemann, 2005) is an obligate herbivore, whereas the mantid Hierodula membranacea (Burmeister, 1838) is an obligatory carnivore. In P. schultei, the luminal activity of all enzymes is approxximately 50% in the crop and 50% in the midgut, which corresponds to the approximate 50 : 50 ratio of volumes of these two regions. These ratios would be expected in insects with a constant feeding rate on an unvaried diet. The enzyme activity and volume ratios in Hierodula membranacea vary considerably because of the irregular feeding habits. These differences in activity ratios between phasmids and mantids are not associated with the obligate phytophagous or carnivorous diet. The ratio of membrane bound to luminal aminopeptidases and disaccharidases in the midgut of both species are not significantly different and are within the normal range of other paurometabolous insects. Cellobiase and other plant cell wall digesting enzymes, laminarinase and cellobiase, are present in the phasmid but totally lacking in the mantid. The obligate carnivorous feeding habits of mantids could represent a selective factor leading to the loss of the ability to produce β-glucanases. Chitinase is a moulting enzyme in all insects, whereas, in H. membranacea, chitinase also occurs as a luminal digestive enzyme. This modified enzyme function requires production and secretion in another tissue, namely the midgut.     

Effect of potassium ions at the different concentration on the interaction between AmB and the lipid monolayer containing cholesterol or ergosterol

AmB is an antifungal drug of polyene. Although it is prone to nephrotoxicity, it is still the gold standard in the clinical treatment of fungal infection. Sterol plays a decisive role in the drug activity of AmB. The antifungal activity of AmB depends on ergosterol in fungal membranes, and its toxicity is related to cholesterol in mammalian membranes. At the same time, AmB interacts with biofilms, leading to a significant loss of potassium ions and affecting the transport of potassium ions across membranes. Meanwhile, metal cation may also affect AmB molecules’ aggregation on the membrane. This paper mainly studied the effects of different concentrations of potassium ions on the interactions between AmB and lipid monolayers containing cholesterol or ergosterol and explored the differences in the impact of varying potassium ions on the drug activity of AmB on monolayers rich in these two kinds of sterols. The results show that potassium ions caused the collapse of lipid monolayer and lipid-AmB monolayer to disappear. The limiting molecular area of these monolayers also increased due to potassium ions. The limiting molecular area of the monolayer in the presence of ergosterol has a great difference in the different concentration of potassium ions, which is different from that in the presence of cholesterol. The presence of potassium ions, regardless of the intensity of K⁺ ions, increased the maximum elastic modulus of the lipid/sterol monolayer with and without AmB. The presence of potassium ions reduced the influence of AmB on the stability of the lipid monolayer containing cholesterol. The impact of AmB on the stability of the lipid monolayer containing ergosterol was related to the concentration of potassium ions. The potassium ions increased the area of the ordered “island” region on the lipid-AmB monolayer containing cholesterol, and the boundary of the microregion produced different degrees of curvature. However, on the lipid/ergosterol monolayer, 5 mM and 10 mM potassium ions made the holes caused by AmB more denser, and the diameter of holes become larger. These results can help to improve the effect of potassium ions on the transmembrane transport of substances affected by AmB. The results will provide a basis for further exploration of the effect mechanism of metal ions on the antifungal activity of polyene drugs.     

Mass spectrometry studies of the fragmentation patterns and mechanisms of protonated peptoids

Peptoids belong to a class of sequence-controlled polymers comprising of N-alkylglycine. This study focuses on using tandem mass spectrometry techniques to characterize the fragmentation patterns of a set of singly and doubly protonated peptoids consisting of one basic residue placed at different positions. The singly protonated peptoids fragment by producing predominately high-abundant C-terminal ions called Y-ions and low-abundant N-terminal ions called B-ions. Computational studies suggest that the proton affinity (PA) of the C-terminal fragments is generally higher than that of the N-terminal fragments, and the PA of the former increases as the fragments are elongated. The B-ions are likely formed upon dissociating the proton-activated amide bonds via an oxazolone structure, and the Y-ions are produced subsequently by abstracting a proton from the newly formed B-ions, which is energetically favored. The doubly protonated peptoids prefer to fragment closest to either the N- or the C-terminus and produce corresponding B/Y-ion pairs. The basic residue seems to dictate the preferred fragmentation site, which may be the result of minimizing the repulsion between the two charges. Water and terminal neutral losses are a facile process accompanying the peptoid fragmentation in both charge states. The patterns appear to be highly influenced by the location of the basic residue.     

Effects of land-use change on functional and taxonomic diversity of Neotropical bats

Human land-use changes are particularly extensive in tropical regions, representing one of the greatest threats to terrestrial biodiversity and a key research topic in conservation. However, studies considering the effects of different types of anthropogenic disturbance on the functional dimension of biodiversity in human-modified landscapes are rare. Here, we obtained data through an extensive review of peer-reviewed articles and compared 30 Neotropical bat assemblages in well-preserved primary forest and four different human-disturbed habitats in terms of their functional and taxonomic diversity. We found that disturbed habitats that are structurally less similar to primary forest (pasture, cropland, and early-stage secondary forest) were characterized by a lower functional and taxonomic diversity, as well as community-level functional uniqueness. These habitats generally retained fewer species that perform different ecological functions compared to higher-quality landscape matrices, such as agroforestry. According to functional trait composition, different bat ensembles respond differently to landscape change, negatively affecting mainly gleaning insectivorous bats in pasture, narrow-range species in cropland, and heavier animalivorous bats in secondary forest. Although our results highlight the importance of higher-quality matrix habitats to support elevated functional and taxonomic bat diversity, the conservation of bat species that perform different ecological functions in the mosaic of human-modified habitats also depends on the irreplaceable conservation value of well-preserved primary forests. Our study based on a pooled analysis of individual studies provides novel insights into the effects of different human-modified habitats on Neotropical bat assemblages.     

Arginine vasopressin does not mediate heat loss in the tail of the rat

It has been reported that hypothermia induced by arginine vasopressin (AVP) is brought about by a coordinated response of reduced thermogenesis in brown adipose tissue (BAT) and increased heat loss through the tail of rats. However, it is well known that AVP is one of the strongest peripheral vasoconstrictors. Whether the AVP-induced hypothermia is associated with an increase in heat loss through the tail is questionable. Therefore, the present study assessed the relationship between the effects of AVP on tail skin temperature and the induced hypothermic response, and to determine if peripheral AVP administration increases heat loss from the tail. Core, BAT and tail skin temperature were monitored by telemetry in male Sprague–Dawley rats before and after intraperitoneal administration of AVP or vasopressin receptor antagonist. We also analyzed simultaneously of the time-course of AVP-induced hypothermic response and its relationship with changes in BAT temperature, and effect of AVP on grooming behavior. The key observations in this study were: (1) rats dosed with AVP induced a decrease in heat production (i.e., a reduction of BAT thermogenesis) and an increase of saliva spreading for evaporative heat loss (i.e., grooming behavior); (2) AVP caused a marked decrease in tail skin temperature and this effect was prevented by the peripheral administration of the vasopressin V1a receptor antagonist, suggesting that exogenous AVP does not increase heat loss in the tail of rats; (3) the vasopressin V1a receptor antagonist could elevate core temperature without affecting tail skin temperature, suggesting that endogenous AVP is involved in suppression of thermogenesis, but not mediates heat loss in the tail of rats. Overall, the present study does not support the conclusion of previous reports that AVP increased tail heat loss in rats, because AVP-induced hypothermia in the rat is accompanied by a decrease in tail skin temperature. The data indicate that exogenous AVP-induced hypothermia attributed to the suppression of thermoregulatory heat production and the increase of saliva spreading for evaporative heat loss.     

Mothers vigilantly guard nests after partial brood loss: a cue of nest predation risk in a paper wasp

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Seasonal acclimatization to the hot summer over 60 days in the Republic of Korea suppresses sweating sensitivity during passive heating

The main objective of this study was to determine the central mechanisms involved in suppression of thermal sweating after seasonal acclimatization (SA) during passive heating (immersing the legs in 43 °C hot water for 30 min). Testing was performed in July (before-SA) and August (after-SA) [25.2±2.2 °C, 73.9±10.3% relative humidity (RH), Cheonan (Chungnam,126° 52′N, 33.38′E), in the Republic of Korea. All experiments were carried out in an automated climatic chamber (25.0±0.5 °C and RH 60.0±3.00%). Twelve healthy men (height, 174.6±5.40 cm; weight, 65.4±5.71 kg; age, 22.7±2.90 yr) participated. The local sweat onset time was delayed in the after-SA compared to that in the before-SA (p<0.001). The local sweat rate and whole body sweat loss volume decreased in the after-SA compared to those in the before-SA (p<0.001). In addition, evaporative loss volume decreased significantly in the after-SA compared to that in the before-SA [chest, upper-back, thigh and forearm (p<0.001)]. Changes in tympanic temperature and mean body temperature were significantly lower (p<0.05) and the basal metabolic rate decreased significantly in the after-SA compared to those in the before-SA (p<0.001). These results suggest that maintenance of a lower body temperature and basal metabolic rate can occur and blunt the central sudomotor mechanisms following seasonal acclimatization, which suppresses sweating sensitivity.     

Yield loss of faba bean (Vicia faba) due to chocolate spot (Botrytis fabae) in sole and mixed cropping systems in Ethiopia

Two field experiments were conducted during 2004 and 2005 cropping seasons at Adet Agricultural Research Center, Ethiopia to assess yield losses caused by chocolate spot(Botrytis fabae) of faba bean in sole and mixed cropping systems using two cultivars. Cropping systems were sole faba bean (FB), faba bean mixed with field pea (FB: FP), barley (FB: BA) and maize (FB: MA). Mancozeb was sprayed at the rate of 2.5 kg a.i/ha at 7-, 14- and 21-day interval to generate different levels of chocolate spot disease in all the four cropping systems, and unsprayed control was also included. The treatments were arranged in a randomised complete block design (RCBD) with four replications. FB: MA mixed cropping significantly reduced disease severity and the area under disease progress curve (AUDPC) and increased faba bean grain yield. The highest faba bean grain yield among the three mixed croppings under different spray schedules was obtained from FB: MA mixed cropping in both 2004 and 2005 (2.56 and 3.74 t/ha, respectively) cropping seasons. There were highly significant yield differences (P < 0.05) among the spray intervals of mancozeb in both seasons. The highest grain yield (4.9 t/h) was recorded from the 7-day spray interval in 2005. The unsprayed faba bean had a lower grain yield (1.9 t/ha in 2004 and 2.3 t/ha in 2005) compared to the sprayed plots. The highest relative yield loss (67.5%) was calculated in 2005 from FB: FP mixed cropping in unsprayed plots. The relative yield losses in the unsprayed plots were in the range of 35.8–41.5% in 2004 and 52.6–67.5% in the 2005 cropping season. Severity and AUDPC were inversely correlated with faba bean grain yield. Significant differences were recorded in the 100-seed weight and days to maturity (DM). The unsprayed plots had shorter DM ranging from 126 to 128.5 day (except FB: MA mixed cropping) in 2004 and 122–123.9 days in 2005. In the sprayed plots DM was relatively longer than the unsprayed plots. A higher seed weight was recorded in the sole FB (56 g) and FB: MA (55 g) mixed cropping, and the lowest value of 100-seed weight was recorded from FB: FP (53 g) mixed cropping. The productivity of the mixed cropping evaluated by land equivalent ratio (LER) exceeded that of sole cropping. Faba bean grain yield was highly influenced by the severity of chocolate spot. The disease affects the DM, forcing early maturing of the plants.