Separation of D- and L-amino acids by ion exchange column chromatography in the form of alanyl dipeptides

Summary A method of ion exchange column chromatography was developed for the determination of D- and L-amino acids in the form of diastereomeric dipeptide. First the protein containing samples were hydrolyzed with 6 molar hydrochloric acid, then the single amino acids were separated in an LKB automated amino acid analyzer with the LKB fraction collector. Following lyophilization, the single amino acids were transformed into alanyl dipeptides with tertiary-butyloxycarbonil-L-alanine-N-hydroxy-succinimide (t-BOC-L-Ala-ONSu) active ester. The alanyl dipeptides were easily separated from one another and the initial amino acids. Determination of the D- and L-amino acids in this form is relatively accurate and reproducible but takes some time (33–38 min). Accuracy of the determination is satisfactory. The coefficient of variation amounts to 3–5%. The use of the method is suggested to laboratories having an amino acid analyzer and wish to determine D-and L-amino acids in synthetic-amino acids complements, peptides or natural materials.     

A new fourier transform approach for protein coding measure based on the format of the Z curve

MOTIVATION: At the core of most protein gene-finding algorithms are the coding measures used to make a decision on coding/non-coding. Of the protein coding measures, the Fourier measure is one of the most important. However, due to the limited length of the windows usually used, the accuracy of the measure is not satisfactory. This paper is devoted to improving the accuracy by lengthening the sequence to amplify the periodicity of 3 in the coding regions. RESULTS: A new algorithm is presented called the lengthen-shuffle Fourier transform algorithm. For the same window length, the percentage accuracy of the new algorithm is 6-7% higher than that of the ordinary Fourier transform algorithm. The resulting percentage accuracy (average of specificity and sensitivity) of the new measure is 84.9% for the window length 162 bp. AVAILABILITY: The program is available on request fromC.- T. Zhang. Contact: ctzhang@tju.edu.cn      

Assessment of the efficiency of a hand-held suction device for sampling spiders: improved density estimation or oversampling?

In the study a comparison is made between the results of two sampling procedures, both based on the application of the same hand-held suction apparatus. Sampling was aimed at spiders, and was carried out on two alfalfa fields. In the first method suction sampling was applied to an enclosure of 0.48 m². The enclosed area was sampled intensively, which was facilitated by the removal of the vegetation. The second method was a transect sampling procedure during which the suction apparatus with a 0.01 m² nozzle was applied to single unenclosed sampling points 1 m apart. A linear series of 48 such subsamples comprised a transect, thus the total area covered in a transect equalled the area of the enclosure. In the transect samples three times more spiders were caught than in the enclosures. This result was consistent on different occasions and at both fields. This basic trend was found in all spider families that were present in significant numbers in the samples. Species composition in the samples collected by the two methods was similar, and species abundance ranks were highly correlated across dates. We propose that an “edge effect” can explain higher catches in transect samples. This edge effect is caused by lateral suction at the edges, which inflated the number of animals caught in the transect application.     

Changes in sperm stores, ejaculate size, fertilization success, and sexual motivation over repeated matings in the common toad, Bufo bufo (Anura: Bufonidae)

Fertilization is of central importance in the determination of reproductive success for both males and females. In species where males have the chance to mate repeatedly within a short period of time, sperm stocks may become depleted and males may have to carefully economize on their sperm reserves. Also, intensive intrasexual competition for females and repeated matings may lead to exhaustion on the behavioural level. To determine whether the reproductive potential of males is limited and if such a limitation is due to behavioural exhaustion or sperm depletion, we experimentally investigated changes in sperm stores, sperm expenditure, fertilization success, and sexual motivation over three repeated matings in the common toad, Bufo bufo , where the breeding season is short and sequential polygyny occurs. At the end of the breeding season, the number of sperm stored in the testes of males mated repeatedly was close to 50% lower than in testes of unmated males. Ejaculate size, which was estimated by applying a novel method allowing direct quantification, decreased by 88% from first to third matings. We also observed a drop in fertilization success from the first two to third matings by 65%, which was largest in males that had started the reproductive season in bad body condition. Some of these males also showed a decreased interest in females in the third mating round. Our results suggest that sperm depletion and loss of sexual motivation may together set a limit to the reproductive potential of common toad males. The present study draws attention to a limitation in reproductive potential, which may occur more often than currently anticipated and has the potential to strongly influence several aspects of reproductive behaviour.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 361–371.     

Body window-enabled in vivo multicolor imaging of transplanted mouse islets expressing an insulin-Timer fusion protein

Type 1 diabetes results from the selective destruction of insulin-producing beta cells in the islets of Langerhans, and autoimmune T cells are thought to be the mediators of this destruction. T cells are also responsible for allorejection once the islets are transplanted into a patient to reduce the negative consequences of a lack of insulin. To better understand these processes, we have developed a transgenic mouse expressing proinsulin II tagged with a live-cell fluorescent reporter protein, Timer. Timer protein is unique because it changes color from green to red in the first 24 h after synthesis. With this marker, insulin synthesis can be carefully monitored through fluorescent changes over time. To complement this new biotechnological research tool, we designed a body window to allow for in vivo imaging over time of the islets transplanted under the kidney capsule. The window device, which is sutured to replace the underlying skin and body wall over the site of islet transplantation, may be used to simultaneously observe beta cells and T cells that have been labeled with a fluorochrome distinguishable from Timer. The imaging of both insulin-producing cells and T cells may be carried out repeatedly for a week or more with no need for repeated surgery, while preserving the life of the studied animal.     

Effect of D,L-carnitine, acetyl-D,L-beta-methylcholine chloride and glycine betaine on some processes of carbohydrate metabolism of humans and goats.

Oral administration of carnitine in normal and diabetic subjects showed a marked decrease in the level of blood glucose during the oral glucose tolerance test (OGTT) except for the three hour samples in diabetic subjects, while a decrease in the level of subsequent blood pyruvate samples was observed during the OGTT in normal and diabetic subjects after the administration of carnitine. During the OGTT, the peak of blood glucose and blood pyruvate level was generally delayed in the diabetic subjects. Furthermore, the mean blood pyruvate levels were elevated above those of normal subjects during the late stages of the test. The mean levels of blood glucose and blood pyruvate of all samples after the administration of carnitine were significantly higher in diabetics than the corresponding values in noramls. Carnitine administration decreased the total blood amino acid nitrogen level only in diabetic subjects. Carnitine caused a highly significant increase in the activity of serum alanine aminotransferase in normal and diabetic subjects, while it had no effect on the activity of serum aspartate aminotransferase. In goats, the level of blood glucose during the intravenous glucose tolerance test (IVGTT) was not affected by carnitine (1,3 or 6 mg/kg body weight). Carnitine in all doses used had no effect on the total blood amino acid nitrogen during the IVGTT, or on the activity of serum alanine aminotransferase and serum aspartate aminotransferase in the fasting samples. Acetyl-D,L-beta-methylcholine had no effect on the level of blood glucose, total blood amino acid nitrogen, the activity of serum alanine aminotransferase or serum aspartate aminotransferase in normal and diabetic subjects. The level of blood pyruvate decreased both in normal and diabetic subjects, in the samples that represented the peak of the curve. Glycine betaine had no effect on blood glucose, pyruvate, total blood amino acid nitrogen and the activity of serum alanine aminotransferase or serum aspartate amino transferase in normal and diabetic subjects or in goats.     

New Atropisomeric Amino Alcohol Ligands for Enantioselective Addition of Diethylzinc to Aldehydes

Efficient synthesis of several new atropisomeric amino alcohols having 1‐phenyl‐1H‐pyrrole skeleton are reported. Steric arrangements of the products were confirmed by a single‐crystal X‐ray measurement. The consequences of the size of the N‐substituents on enantioinduction were examined by employing the enantioselective catalytic addition of diethylzinc to a series of substituted benzaldehydes (yields 91–97%, up to 85% enantiomeric excess). The special effect of the ortho methoxy group of the substrate on the enantioinduction is also interpreted. Chirality 27:216–222, 2015. © 2014 Wiley Periodicals, Inc.     

Western Palaearctic phylogeography of an inquiline oak gall wasp,Synergus umbraculus

Insect‐induced galls on plants comprise species‐rich but self‐contained communities of herbivores and natural enemies. In the present study, we focus on galls induced by cynipid gall wasps on oaks, and on the least‐known trophic level that these galls contain: inquilines. These insects, also cynipids, feed on gall tissue and are an abundant but taxonomically poorly understood part of an otherwise well‐studied system. We used DNA sequence data to examine spatial patterns in the genetic diversity of Synergus umbraculus Olivier 1791 (Hymenoptera: Cynipidae: Synergini), a widespread species attacking many host galls across the Western Palaearctic. Analysis of 239 cytochrome b sequences revealed eight haplogroups showing significant phylogeographic pattern across the Western Palaearctic, corresponding to putative glacial refugia in Iberia, Central Europe, Turkey, and Iran. There were significant genetic discontinuities across the Pyrenees and the Anatolian diagonal but no impact of the Alps, suggesting that significant discontinuities have biotic rather than physical causes. Detailed analysis of sites in the Carpathian Basin reveal a high diversity and low spatial structure, and identify Central Europe as the source of colonists for Quaternary colonization of Germany, France, and Britain. We found no evidence for host‐associated differentiation of S. umbraculus lineages associated with the most common cynipid host galls, suggesting frequent shifts within the host gall assemblage by inquiline lineages. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 750–764.     

The keystone role of anostracans and copepods in European soda pans during the spring migration of waterbirds

1. The European soda pans of the Carpathian Basin provide important stopover sites for several waterbird species. We studied the effect of different invertebrate food types and other characteristics on the habitat choice and distribution of birds on 82 pans (in Hungary, Austria and Serbia) during spring migration. 2. Only three environmental variables proved to be significant determinants of the waterbird communities: pan density (spatial effect) along with the density of Arctodiaptomus spp. and anostracans (local effect). Variance partitioning of the data revealed that aquatic invertebrate food supply (Arctodiaptomus and anostracans) had a greater effect than pan density on the 10 investigated bird species, suggesting a dominant role of species sorting in structuring the communities. Pied avocets (Recurvirostra avosetta) and northern shovelers (Anas clypeata) differed from the other species in their strong association with densities of anostracans (avocet) and Arctodiaptomus (shoveler). 3. Anostracans and microcrustaceans, especially the most frequent Branchinecta orientalis, Arctodiaptomus spinosus and Arctodiaptomus bacillifer, can be regarded as keystone elements of this soda pan habitat because of their bottom‐up role in structuring waterbird assemblages during spring migration.