Climate‐driven speedup of alpine treeline forest growth in the Tianshan Mountains,Northwestern China

Forest growth is sensitive to interannual climatic change in the alpine treeline ecotone (ATE). Whether the alpine treeline ecotone shares a similar pattern of forest growth with lower elevational closed forest belt (CFB) under changing climate remains unclear. Here, we reported an unprecedented acceleration of Picea schrenkiana forest growth since 1960s in the ATE of Tianshan Mountains, northwestern China by a stand‐total sampling along six altitudinal transects with three plots in each transect: one from the ATE between the treeline and the forest line, and the other two from the CFB. All the sampled P. schrenkiana forest patches show a higher growth speed after 1960 and, comparatively, forest growth in the CFB has sped up much slower than that in the ATE. The speedup of forest growth at the ATE is mainly accounted for by climate factors, with increasing temperature suggested to be the primary driver. Stronger water deficit as well as more competition within the CFB might have restricted forest growth there more than that within the ATE, implying biotic factors were also significant for the accelerated forest growth in the ATE, which should be excluded from simulations and predictions of warming‐induced treeline dynamics.     

Growth and development of Encarsia formosa (Hymenoptera: Aphelinidae) in the greenhouse whitefly, Trialeurodes vaporariorum (Homoptera: Aleyrodidae): effect of host age

The tiny parasitoid wasp, Encarsia formosa, has been used successfully to control greenhouse whiteflies (GHWFs) in greenhouses in many countries throughout the world. Therefore, there has been considerable interest in developing methods for artificially rearing this wasp. However, little information is available concerning the regulation of its development including the host-parasitoid interactions that are required for the parasitoid to complete its life cycle. Here we confirm that parasitoid developmental rates differ significantly based upon the host instar parasitized. Development was faster when 3rd and 4th instar GHWFs were offered for parasitization than when 1st or 2nd instars were used. Our results show that it is primarily the embryo and the first two parasitoid instars that exhibit prolonged developmental times when 1st and 2nd instar whiteflies are parasitized. Although percent emergence was not affected by host age at the time of parasitization, adult longevity as well as adult emergence pattern varied greatly depending upon the instar parasitized. When 3rd and 4th instar GHWFs were selected for oviposition, adult wasps lived significantly longer than when 1st or 2nd instars were used; also, there was a sharp emergence peak on the 2nd day after emergence was first observed (reduced or absent when 1st or 2nd instar GHWFs were parasitized) and the emergence period was reduced from between 8 and 11 days to 5 days. In general, the younger the host instar parasitized, the less synchronous was parasitoid development. Previous reports that E. formosa will not molt to the 2nd instar until the host has reached its 4th instar were not confirmed. When 1st instar host nymphs were parasitized, 2nd instar parasitoids were detected in 3rd instar hosts. Importantly, however, no matter which instar was parasitized, the parasitoid never molted to its last instar until the host had reached Stage 5 of its last instar, a stage in which host pharate adult formation has been initiated. It appears, then, that a condition(s) associated with host pharate adult formation is required for the parasitoid's final larval molt. Results reported here should facilitate the development of in vitro rearing systems for E. formosa.     

Molecular and computational approaches to understand resistance of New Delhi metallo β-lactamase variants (NDM-1, NDM-4, NDM-5, NDM-6, NDM-7)-producing strains against carbapenems

The discovery of NDM-1 and its variants has caused the emergence of antibiotic resistance in the community and hospital setting, causing major concern for health care across the globe. New Delhi Metallo-β-lactamase is known to hydrolyse almost all β-lactam antibiotics. Studies have shown the hydrolytic activates of NDM-1 and some of its variants, however a comparative study of these NDM variants has not been explored in detail. Hence, we proposed to check their catalytic activity by performing a comparative study between NDM-1 and its variants. The study was initiated to clone NDM variants (NDM-1, NDM-4, NDM-5, NDM-6 and NDM-7) followed by overexpression of the recombinant proteins to check their hydrolytic properties against β-lactam antibiotics. The minimum inhibitory concentration of carbapenems antibiotics for bla_NDM-5 clone was found four fold increased, whereas no change was observed in the clones having other variants. The hydrolytic activity of carbapenem with NDM-5 variant was found to be augmented as per the kinetics parameter where Km was decreased and kcat, kcat/Km values increased as compared to the NDM-1. Molecular docking studies were employed to identify the variations in the binding ability among all NDM variants with imipenem or meropenem. Simulation studies at 100?ns showed a good stability of NDM-5 with imipenem and meropenem as compared to NDM-1. CD spectroscopy data revealed significant changes in the secondary structure of NDM variants. We conclude that NDM-5 showed higher hydrolytic activity as compared to other variants. This study provides a comparative analysis of the severity of NDM producing strains.     

Heterogeneous origin of carbonic anhydrase activity of thylakoid membranes

Carbonic anhydrase activities of pea thylakoids as well as thylakoid fragments enriched either in Photosystem 1 (PS1-membranes) or Photosystem 2 (PS2-membranes) were studied. The activity of PS1-membranes if calculated on chlorophyll basis was much higher than the activity of PS2-membranes. Acetazolamide, a non-permeable inhibitor of carbonic anhydrases, increased carbonic anhydrase activity of PS2-membranes at concentrations lower than 10⁻⁶ M and suppressed this activity only at higher concentrations. A lipophilic inhibitor of carbonic anhydrases, ethoxyzolamide, effectively suppressed the carbonic anhydrase activity of PS2-membranes (I ₅₀ = 10⁻⁹ M). Carbonic anhydrase activity of PS1-membranes was suppressed alike by both inhibitors (I ₅₀ = 10⁻⁶ M). In the course of the electrophoresis of PS2-membranes treated with n-dodecyl-β-maltoside “high-molecular-mass” carbonic anhydrase activity was revealed in the region corresponding to core-complex of this photosystem. Besides, carbonic anhydrase activity in the region of low-molecular-mass proteins was discovered in the course of such an electrophoresis of both PS2-and PS1-membranes. These low-molecular-mass carbonic anhydrases eluted from corresponding gels differed in sensitivity to specific carbonic anhydrase inhibitors just the same as PS1-membranes versus PS2-membranes. The results are considered as evidence for the presence in the thylakoid membranes of three carriers of carbonic anhydrase activity. Published in Russian in Biokhimiya, 2006, Vol. 71, No. 5, pp. 651–659.     

Variation between mouse major urinary protein genes isolated from a single inbred line

We describe ten Charon 4A genomic DNA clones from BALB/c mice which include at least seven different major urinary protein (MUP) genes. We have established the orientation of all seven sequences, and have placed six of them in precise register by means of restriction site maps and Southern blot hybridization with cloned cDNA sequences. Four of the seven genomic sequences (family I sequences) form hybrids with six independent cDNA clones that have a high thermal stability and hybridize more strongly with mRNA from three inbred mouse lines. Hybrids between the remaining three genomic sequences and the cDNA clones have a lower thermal stability and hybridize less strongly with mRNA from the three inbred lines. Homologies between different cloned sequences extend over as much as 15 kb. No clone contains parts of two MUP genes, and no homology has been detected between the 3' flanking region of one MUP gene and the 5' flanking region of another.     

Human body mass estimation: a comparison of "morphometric" and "mechanical" methods

In the past, body mass was reconstructed from hominin skeletal remains using both "mechanical" methods which rely on the support of body mass by weight-bearing skeletal elements, and "morphometric" methods which reconstruct body mass through direct assessment of body size and shape. A previous comparison of two such techniques, using femoral head breadth (mechanical) and stature and bi-iliac breadth (morphometric), indicated a good general correspondence between them (Ruff et al. [1997] Nature 387:173-176). However, the two techniques were never systematically compared across a large group of modern humans of diverse body form. This study incorporates skeletal measures taken from 1,173 Holocene adult individuals, representing diverse geographic origins, body sizes, and body shapes. Femoral head breadth, bi-iliac breadth (after pelvic rearticulation), and long bone lengths were measured on each individual. Statures were estimated from long bone lengths using appropriate reference samples. Body masses were calculated using three available femoral head breadth (FH) formulae and the stature/bi-iliac breadth (STBIB) formula, and compared. All methods yielded similar results. Correlations between FH estimates and STBIB estimates are 0.74-0.81. Slight differences in results between the three FH estimates can be attributed to sampling differences in the original reference samples, and in particular, the body-size ranges included in those samples. There is no evidence for systematic differences in results due to differences in body proportions. Since the STBIB method was validated on other samples, and the FH methods produced similar estimates, this argues that either may be applied to skeletal remains with some confidence.     

Role of hydroxyl containing residues in the intracellular region of rat bradykinin B(2) receptor in signal transduction, receptor internalization, and resensitization

In past reports we illustrated the importance of Y131, Y322, and T137 within the intracellular (IC) face of the rat bradykinin B2 receptor (rBKB2R) for signal transduction and receptor maintenance (Prado et al. [1997] J. Biol. Chem. 272:14638-14642; Prado et al. [1998] J. Biol. Chem. 273:33548-33555). In this report, we mutate the remaining hydroxyl possessing residues located within the rBKB2R IC region. Exchange of S139A (IC2) or T239V (IC3) did not affect BK activated phosphatidylinositol (PI) turnover or receptor internalization. Chimeric exchange of the last 34 amino acids of BKB2R C-terminus with the corresponding 34 amino acids of the rat angiotensin II AT1a receptor (rAT1aR), both containing an S/T cluster, resulted in a mutant with normal endocytosis and BK activated PI turnover. A more selective chimera of these S/T clusters, with an exchange of BKB2R (333-351) with a rAT1aR fragment (326-342), resulted in a receptor with a retarded internalization but a normal BK activated PI turnover. Subsequent mutation of rBKB2R T344V showed little change in receptor uptake but a pronounced loss of BK activated PI turnover. The mutation of S335A, S341A, S348A, and S350A resulted in very poor receptor internalization and loss of activated PI turnover. Closer examination of this serine cluster illustrated that the replacement of S348A led to poor internalization; whereas the retention of S348 and mutation of S341A resulted in a receptor with a much greater internalization than WT. These and other results suggest that the presence of S348 promotes internalization while the presence of S341 dampens it. Conversely, S341 and S350 proved important for receptor signaling. In sum, our results illustrate that the distal C-terminus including its S/T cluster is important for both rBKB2R internalization and signal transduction. Individual S/T residues within this cluster appear involved in either signal transmission or receptor uptake capacity. However, replacement of the entire distal tail region with the corresponding rAT1aR sequence, also containing an S/T cluster, enables the BKB2R/AT1aR chimera to act in a very similar manner to wild type rBKB2R.     

Dimebon attenuates methamphetamine, but not MPTP, striatal dopamine depletion

Dimebon is an anti-histamine with central nervous system activity. In this report the effects of dimebon as a neuroprotectant in animal models of Parkinson's disease were tested as assessed in methamphetamine- and MPTP-induced striatal dopaminergic toxicity. Dimebon (1mg/kg) administered at 30 min prior to methamphetamine (40mg/kg) significantly reduced the amount of striatal dopamine depletion in mice, without altering the initial methamphetamine-induced increase in body temperature. In contrast, dimebon at either 1 or 25mg/kg administered at 30 min prior to MPTP (35 mg/kg) was unable to prevent MPTP-induced striatal dopamine loss as determined at 7 days post-methamphetamine/MPTP. These data suggest that dimebon may be exerting a neurotoxin specific neuroprotective effect upon the striatal dopaminergic system and may serve as an important tool for discriminating the mechanistic basis of these two dopaminergic neurotoxins.