New regioselective derivatives of sucrose with amino acid and acrylic groups

We report here a range of new sucrose derivatives obtained from '3-ketosucrose' in aqueous medium with few reaction steps. As an intermediate, 3-amino-3-deoxy-alpha-D-allopyranosyl beta-D-fructofuranoside (1) was obtained via the classical route of reductive amination with much improved yield and high stereoselectivity. Building blocks for polymerization were synthesized by introduction of acrylic-type side chains, for example, with methacrylic anhydride. Corresponding polymers were synthesized. Aminoacyl and peptide conjugates were obtained through conventional peptide synthesis with activated and protected amino acids. Deprotection yielded new glycoderivatives having an unconventional substitution pattern, namely 3-(aminoacylamino) allosaccharides. Both mono- and di-peptide conjugates of allosucrose have been synthesized.     

Differential growth identified in salamander larvae half‐sib cohorts: Survival strategy?

In this study we describe the growth of several different larval cohorts (i.e. half-siblings of the same mother born on the same day) of a rare, xeric-adapted salamander Salamandra s. infraimmaculata Martens, 1885, under constant density and food conditions from birth to metamorphosis. The larvae spend the critical first phase of their lives in water, mostly in temporary ponds. Age and weight at metamorphosis were highly affected by varying food conditions. We have identified six different growth modes that these larvae use, both fast growing and slow growing. Each larval cohort was found to use 2-4 different such growth modes regardless of their initial weight. Fast growing modes (I-III) will enable larvae to survive dry years, and metamorphose bigger. Slow growing modes (IV-VI), used by 8% of the larval population, will enable survival only in rainy years. These last growth modes effect differential temporal dispersal in wet years by delaying the emergence of postmetamorphs onto land. Distribution of growth modes in the larval population is affected by food but not by density conditions. Late-born, fast-growing larvae will have an advantage in dry years being able to metamorphose and disperse, whereas the slow-growing larvae will survive only in wet years.     

Phylogenetic reconstruction of the wolf spiders (Araneae: Lycosidae) using sequences from the 12S rRNA, 28S rRNA, and NADH1 genes: implications for classification, biogeography, and the evolution of web building behavior

Current knowledge of the evolutionary relationships amongst the wolf spiders (Araneae: Lycosidae) is based on assessment of morphological similarity or phylogenetic analysis of a small number of taxa. In order to enhance the current understanding of lycosid relationships, phylogenies of 70 lycosid species were reconstructed by parsimony and Bayesian methods using three molecular markers; the mitochondrial genes 12S rRNA, NADH1, and the nuclear gene 28S rRNA. The resultant trees from the mitochondrial markers were used to assess the current taxonomic status of the Lycosidae and to assess the evolutionary history of sheet-web construction in the group. The results suggest that a number of genera are not monophyletic, including Lycosa, Arctosa, Alopecosa, and Artoria. At the subfamilial level, the status of Pardosinae needs to be re-assessed, and the position of a number of genera within their respective subfamilies is in doubt (e.g., Hippasa and Arctosa in Lycosinae and Xerolycosa, Aulonia and Hygrolycosa in Venoniinae). In addition, a major clade of strictly Australasian taxa may require the creation of a new subfamily. The analysis of sheet-web building in Lycosidae revealed that the interpretation of this trait as an ancestral state relies on two factors: (1) an asymmetrical model favoring the loss of sheet-webs and (2) that the suspended silken tube of Pirata is directly descended from sheet-web building. Paralogous copies of the nuclear 28S rRNA gene were sequenced, confounding the interpretation of the phylogenetic analysis and suggesting that a cautionary approach should be taken to the further use of this gene for lycosid phylogenetic analysis.     

短时低温对马铃薯甲虫种群增长的影响

[目的]马铃薯甲虫Leptinotarsa decemlineata是我国重要的检疫性害虫,对茄科植物危害严重.本研究旨在明确出现倒春寒短时低温对马铃薯甲虫种群增长的影响.[方法]马铃薯甲虫卵在8℃下分别处理1,3和5d,以27℃下饲养的卵作为对照,调查卵孵化率及孵化后幼虫的生长发育和成虫繁殖情况,用种群参数评估短时低...     

A synthetic hexapeptide designed to resemble a proteinaceous P-loop nest is shown to bind inorganic phosphate

The hexapeptide Ser-Gly-Ala-Gly-Lys-Thr has been synthesized and characterized. It was designed as a minimal soluble peptide that would be likely to have the phosphate-binding properties observed in the P-loops of proteins that bind the β-phosphate of GTP or ATP. The β-phosphate in such proteins is bound by a combination of the side chain ε-amino group of the lysine residue plus the concavity formed by successive main chain peptide NH groups called a nest, which is favored by the glycines. The hexapeptide is shown to bind HPO(4) (2-) strongly at neutral pH. The affinities of the various ionized species of phosphate and hexapeptide are analyzed, showing that they increase with pH. It is likely the main chain NH groups of the hexapeptide bind phosphate in much the same way as the corresponding P-loop atoms bind the phosphate ligand in proteins. Most proteinaceous P-loops are situated at the N-termini of α-helices, and this observation has frequently been considered a key aspect of these binding sites. Such a hexapeptide in isolation seems unlikely to form an α-helix, an expectation in accord with the CD spectra examined; this suggests that being at the N-terminus of an α-helix is not essential for phosphate binding. An unexpected finding about the hexapeptide-HPO(4) (2-) complex is that the side chain ε-amino group of the lysine occurs in its deprotonated form, which appears to bind HPO(4) (2-) via an N···H-O-P hydrogen bond.     

Behavioral differentiation during collective building in wild mice Mus spicilegus

Although well documented in social insects, the possibility of behavioral differentiation during collective building has been poorly studied in mammals. In this context, the mound-building mouse Mus spicilegus is an interesting model. Under natural conditions, juveniles from different litters gather vegetal material and build a sophisticated structure, the mound, under which the mice will spend winter. The first steps of this complex building process may be elicited under laboratory conditions by offering cotton balls as building material. Spatio-temporal distribution of both animals and cotton balls was automatically recorded by RFID (Radio-Frequency Identification Device) technique. Our results revealed a behavioral differentiation during a collective building task. In a group of six individuals, only two mice (called carriers) transported 80% of the building material whereas the contribution of the remaining mice was weak or even non-existent. The proportion of carriers was constant in all of the six groups studied. This behavioral differentiation was implemented immediately after the building material was made available and remained stable during the 4 days of experiment. The high contribution level of carriers did not result from resource monopolization, nor did it depend on the gender or parental origin of the mice.     

Predictive models for transient protein expression in tobacco (Nicotiana tabacum L.) can optimize process time, yield, and downstream costs

The transient expression of recombinant biopharmaceutical proteins in plants can suffer inter‐batch variation, which is considered a major drawback under the strict regulatory demands imposed by current good manufacturing practice (cGMP). However, we have achieved transient expression of the monoclonal antibody 2G12 and the fluorescent marker protein DsRed in tobacco leaves with ～15% intra‐batch coefficients of variation, which is within the range reported for transgenic plants. We developed models for the transient expression of both proteins that predicted quantitative expression levels based on five parameters: The OD_600nm of Agrobacterium tumefaciens (from 0.13 to 2.00), post‐inoculation incubation temperature (15–30°C), plant age (harvest at 40 or 47 days after seeding), leaf age, and position within the leaf. The expression models were combined with a model of plant biomass distribution and extraction, generating a yield model for each target protein that could predict the amount of protein in specific leaf parts, individual leaves, groups of leaves, and whole plants. When the yield model was combined with a cost function for the production process, we were able to perform calculations to optimize process time, yield, or downstream costs. We illustrate this procedure by transferring the cost function from a production process using transgenic plants to a hypothetical process for the transient expression of 2G12. Our models allow the economic evaluation of new plant‐based production processes and provide greater insight into the parameters that affect transient protein expression in plants. Biotechnol. Bioeng. 2012; 109: 2575–2588. © 2012 Wiley Periodicals, Inc.     

Experimental test of nest-site limitation in mature mixed forests of central British Columbia,Canada

Nest-site availability limits cavity-using populations in many harvested forests; however, little is known about the extent of nest-site limitation in mature forests with a full complement of excavator species and intact processes of cavity creation and loss. To examine the role of nest-site availability in limiting cavity-using populations in mature mixed conifer forests in central British Columbia, Canada, we conducted an 11-year before-after control-impact experiment in which we increased nest-site availability via nest box addition. Our 7 sites (3 treatments, 4 controls) had low cavity densities (<2/ha) prior to treatment and cavity occupation rates were also low (<10%/yr), which is a relationship often cited in the literature as evidence of non-limitation in cavity-nesting populations. Following nest box addition at our treatment sites, which tripled the availability of cavities, total density of bird and mammal nests more than tripled. Density of mountain chickadee (Poecile gambeli) nests increased 9-fold on treatment sites and returned to pre-treatment levels following box removal, suggesting that chickadee populations were limited by cavity availability at our study sites. Density of red squirrel (Tamiasciurus hudsonicus) and northern flying squirrel (Glaucomys sabrinus) nests and roosts also increased significantly at treatment sites following box addition and declined following box removal. We noted little change in chickadee or squirrel nest density at control sites monitored concurrently. Squirrels preferred large-sized over small-sized boxes, and significantly enlarged the entrance areas of small boxes by chewing, suggesting that there may have been a shortage of suitable nest and roost sites for them in our study area. We contend that low cavity occupancy rates may not accurately reflect nest-site availability for cavity nesters in mature forests, and that cavity size may influence the true availability of cavities on the landscape. © 2011 The Wildlife Society.     

Snowy plover nest survival in Kansas and effective management to counter negative effects of precipitation

Snowy plovers (Charadrius nivosus) are a species of conservation concern throughout North America and listed as a threatened species in Kansas. Management to minimize the effects of flooding and predation were implemented at Kansas breeding sites in the 1980s to encourage reproductive success. However, the effectiveness of those strategies and the effect of other variables that may influence nest survival have not been formally assessed. We used Program MARK to model the daily survival rate (DSR) of 317 snowy plover nests with 14 habitat- and management-related covariates to identify factors that influence nest survival and examine the efficacy of current management practices. In 2005 and 2006, we monitored nests and collected habitat data at the 2 known breeding sites in Kansas, Quivira National Wildlife Refuge (NWR) and Cheyenne Bottoms Wildlife Area (WA). Overall DSR was greater at Quivira NWR in 2006 (0.954) than at Cheyenne Bottoms WA (0.917) and Quivira NWR (0.942) in 2005. We developed 88 candidate models of which 4 competing models (ΔAIC_c < 2) were identified. We selected the most parsimonious model (K = 14, w_i = 0.23) as the remaining 3 included covariates deemed biologically uninformative. This model included the effect of study site and year on a quadratic time trend, and included covariates quantifying nest age; precipitation; the proportion of gravel, rock, and vegetation at nests; occurrence within an electric fence and within 20 m of a road; occurrence on a human-constructed nest mound; and adult capture during incubation. We found a strong positive relationship between the use of nest mounds and DSR, and a strong negative relationship between precipitation and DSR. We also found a strong positive relationship between DSR and the proportion of vegetation at nest sites, the occurrence of a nest within an electric fence, and adult capture at a nest. We noted a strong negative relationship between DSR and occurrence within 20 m of a road. However, we found that DSR was not sensitive to the proportion of vegetation at a nest, occurrence within an electric fence or within 20 m of a road, and to adult capture at a nest in light of covariates quantifying precipitation and the use of nest mounds. We found weak support for a positive relationship between DSR, nest age, and the proportion of gravel and rock at nests. Our results indicate that large rainfall events are a major source of snowy plover nest loss in Kansas that can be mitigated by the construction of nest mounds. Limited influence of environmental variables found to influence nest survival at other breeding sites suggests that threats to snowy plover nest survival are site specific and managers should assess local sources of nest loss prior to implementing management strategies to improve reproductive success. © 2012 The Wildlife Society.     

A thermodynamic comparison of arboreal and terrestrial sleeping sites for dry-habitat chimpanzees (Pan troglodytes schweinfurthii) at the Toro-Semliki Wildlife Reserve, Uganda

The nightly construction of an arboreal sleeping platform (SP) has been observed among every chimpanzee's population studied to date. Here, we report on bioclimatic aspects of SP site choice among dry-habitat chimpanzees (Pan troglodytes schweinfurthii) at the Toro-Semliki Wildlife Reserve, Uganda. We placed a portable weather monitor within 1 m of chimpanzee SPs and compared the microenvironment of this site with terrestrial monitors placed 10 cm above the ground directly underneath the simultaneously studied SP. We calculated physical "comfort levels" of monitored sites using the RayMan thermophysiological model that we modified to take ape body proportions into account. The RayMan tool gauges energy balance using wind speed, temperature, relative humidity, and heat index in conjunction with the study subject's mass and stature to determine whether the individual is in energy balance or homeostasis. We found that (1) terrestrial microclimates have greater homeostatic potential than arboreal microclimates, and (2) there is a significant positive linear relationship between wind speed and height of SP in the forest canopy. Advantages of terrestrial sites are that they require lesser energetic expenditure to stabilize the body when the SP is under construction and perhaps during use as well. We found that terrestrial sites also had better homeostatic potentials. This combination of advantages explains why SPs are so often sited terrestrially in habitats where predation risk is low. Early hominins must have had technological or social measures to avoid or deter predators that were significantly advanced over those found among chimpanzees before they began sleeping on the ground.