Functional Interrogation of Adult Hypothalamic Neurogenesis with Focal Radiological Inhibition

The functional characterization of adult-born neurons remains a significant challenge. Approaches to inhibit adult neurogenesis via invasive viral delivery or transgenic animals have potential confounds that make interpretation of results from these studies difficult. New radiological tools are emerging, however, that allow one to noninvasively investigate the function of select groups of adult-born neurons through accurate and precise anatomical targeting in small animals. Focal ionizing radiation inhibits the birth and differentiation of new neurons, and allows targeting of specific neural progenitor regions. In order to illuminate the potential functional role that adult hypothalamic neurogenesis plays in the regulation of physiological processes, we developed a noninvasive focal irradiation technique to selectively inhibit the birth of adult-born neurons in the hypothalamic median eminence. We describe a method for Computer tomography-guided focal irradiation (CFIR) delivery to enable precise and accurate anatomical targeting in small animals. CFIR uses three-dimensional volumetric image guidance for localization and targeting of the radiation dose, minimizes radiation exposure to nontargeted brain regions, and allows for conformal dose distribution with sharp beam boundaries. This protocol allows one to ask questions regarding the function of adult-born neurons, but also opens areas to questions in areas of radiobiology, tumor biology, and immunology. These radiological tools will facilitate the translation of discoveries at the bench to the bedside.     

Multilocus heterozygosity and inbreeding in the Siberian jay

Because of its common negative association with fitness, inbreeding is a major concern in conservation biology. Traditionally it has been measured as individual inbreeding coefficient calculated from the pedigree, but recently multilocus heterozygosity estimates have become commonly used as proxies. However, theoretical and simulation studies have cast doubt on the validity of these surrogates especially when they are based on only a few molecular markers. Yet, empirical studies reporting the correlation between multilocus heterozygosity and inbreeding coefficient are rare. We studied this relationship in a wild Siberian jay (Perisoreus infaustus) population subject to a long-term field study over 30 years. The correlations between inbreeding coefficient and the employed heterozygosity measures—standardized heterozygosity and internal relatedness—based on 21 microsatellite loci were weak. These results together with results from theoretical and simulation studies caution against use of multilocus heterozygosity estimates to study inbreeding in natural populations.     

Introduced Siberian chipmunks are more heavily infested by ixodid ticks than are native bank voles in a suburban forest in France

By serving as hosts for native vectors, introduced species can surpass native hosts in their role as major reservoirs of local pathogens. During a 4-year longitudinal study, we investigated factors that affected infestation by ixodid ticks on both introduced Siberian chipmunks Tamias sibiricus barberi and native bank voles Myodes glareolus in a suburban forest (Forêt de Sénart, Ile-de-France). Ticks were counted on adult bank voles and on adult and young chipmunks using regular monthly trapping sessions, and questing ticks were quantified by dragging. At the summer peak of questing Ixodes ricinus availability, the average tick load was 27-69 times greater on adult chipmunks than on adult voles, while average biomass per hectare of chipmunks and voles were similar. In adult chipmunks, individual effects significantly explained 31% and 24% of the total variance of tick larvae and nymph burdens, respectively. Male adult chipmunks harboured significantly more larvae and nymphs than adult females, and than juveniles born in spring and in summer. The higher tick loads, and more specifically the ratio of nymphs over larvae, observed in chipmunks may be caused by a higher predisposition - both in terms of susceptibility and exposure - to questing ticks. Tick burdens were also related to habitat and seasonal variation in age- and sex-related space use by both rodents. Introduced chipmunks may thus have an important role in the dynamics of local vector-borne pathogens compared with native reservoir hosts such as bank voles.     

The ontogeny of the Late Permian terebratulids (Brachiopoda) Gruntelasma Smirnova, Grigorjevaelasma Smirnova, and Campbellelasma Smirnova and their taxonomic position

A specific type of ontogenetic change combining elements of dielasmoid and angustothyridid stages of brachidium development is established for the Late Permian genera Gruntelasma Smirnova, 2004, Grigorjevaelasma Smirnova, 2004, and Campbellelasma Smirnova, 2004 from the Russian Platform. On this basis, these genera are assigned to the superfamily Compositelasmatoidea Smirnova, family Compositelasmatidae.     

Phylogenetic reconstruction at the species and intraspecies levels in the genus Pisum (L.) (peas) using a histone H1 gene

A phylogenetic analysis of the genus Pisum (peas), embracing diverse wild and cultivated forms, which evoke problems with species delimitation, was carried out based on a gene coding for histone H1, a protein that has a long and variable functional C-terminal domain. Phylogenetic trees were reconstructed on the basis of the coding sequence of the gene His5 of H1 subtype 5 in 65 pea accessions. Early separation of a clear-cut wild species Pisum fulvum is well supported, while cultivated species Pisum abyssinicum appears as a small branch within Pisum sativum. Another robust branch within P. sativum includes some wild and almost all cultivated representatives of P. sativum. Other wild representatives form diverse but rather subtle branches. In a subset of accessions, PsbA-trnH chloroplast intergenic spacer was also analysed and found less informative than His5. A number of accessions of cultivated peas from remote regions have a His5 allele of identical sequence, encoding an electrophoretically slow protein product, which earlier attracted attention as likely positively selected in harsh climate conditions. In PsbA-trnH, a 8bp deletion was found, which marks cultivated representatives of P. sativum.     

High-value chemicals obtained from selective photo-oxidation of glucose in the presence of nanostructured titanium photocatalysts

Glucose was oxidized in the presence of powdered TiO(2) photocatalysts synthesized by an ultrasound-promoted sol-gel method. The catalysts were more selective towards glucaric acid, gluconic acid and arabitol (total selectivity approx. 70%) than the most popular photocatalyst, Degussa P-25. The photocatalytic systems worked at mild reaction conditions: 30°C, atmospheric pressure and very short reaction time (e.g. 5 min). Such relatively good selectivity towards high-valued molecules are attributed to the physico-chemical properties (e.g. high specific surface area, nanostructured anatase phase, and visible light absorption) of novel TiO(2) materials and the reaction conditions. The TiO(2) photocatalysts have potential for water purification and energy production and for use in the pharmaceutical, food, perfume and fuel industries.     

Diet affects resting, but not basal metabolic rate of normothermic Siberian hamsters acclimated to winter

We examined the effect of different dietary supplements on seasonal changes in body mass (m_b), metabolic rate (MR) and nonshivering thermogenesis (NST) capacity in normothermic Siberian hamsters housed under semi-natural conditions. Once a week standard hamster food was supplemented with either sunflower and flax seeds, rich in polyunsaturated fatty acids (FA), or mealworms, rich in saturated and monounsaturated FA. We found that neither of these dietary supplements affected the hamsters' normal winter decrease in m_b and fat content nor their basal MR or NST capacity. NST capacity of summer-acclimated hamsters was lower than that of winter-acclimated ones. The composition of total body fat reflected the fat composition of the dietary supplements. Resting MR below the lower critical temperature of the hamsters, and their total serum cholesterol concentration were lower in hamsters fed a diet supplemented with mealworms than in hamsters fed a diet supplemented with seeds. These results indicate that in mealworm-fed hamsters energy expenditure in the cold is lower than in animals eating a seed-supplemented diet, and that the degree of FA unsaturation of diet affects energetics of heterotherms, not only during torpor, but also during normothermy.     

Oil content,fatty acid composition and biodiesel properties among natural provenances of Siberian apricot (Prunus sibirica L.) from China

Siberian apricot (Prunus sibirica L.), an excellent woody oil plant unique to Asia, is well known for its ability to produce high‐oil seeds for use as a promising feedstock of biodiesel. Based on the investigation of natural Siberian apricot resources in China in the early stage, seeds of Siberian apricot from 74 geographic provenances which can fully reflect the overall information were collected. In this research, seeds oil content, fatty acid composition and biodiesel properties were evaluated, and the key environmental factors that caused the variation of these in different geographic provenance were analyzed. The oil content of Siberian apricot seeds is 45.48%–61.07%, and the average was 50.95% for all provenances. The characteristics of oil can identify and quantify eight fatty acids. The most abundant fatty acids were oleic acid (C18:1; 54.02%–76.54%), followed by linoleic acid (C18:2; 16.78%–38.49%) and erucic acid (C16:0; from 3.27% to 6.12%). Monounsaturated fatty acids are the most abundant in 54.75%–77.03% compared with saturated fatty acids and polyunsaturated fatty acids. The biodiesel properties of most provenance seeds meet the standards of the ASTM D6751 and GB/T 20828, and a few meet the standards of the EN14214. Through the clustering of oil content and fatty acid composition and the analysis of biodiesel properties indexes, it is concluded that KSK provenance is the most suitable for biodiesel production. The XBZ, HHE, AES, ZLQ and LD provenances may be preserved as potential biodiesel. RDA and VPA showed that the effects of environmental factors on the oil properties of Siberian apricot were ranked as terrain factor > climate factor > soil factor, among which longitude, latitude and altitude are the main terrain indicators. These evaluations can provide reference for the effective utilization and further development of Siberian apricot as a bioenergy feedstock.     

Contrasting seasonal dynamics in fleas of the Siberian flying squirrel (Pteromys volans) in Finland

Abstract.  1. The seasonal and spatial variation of the adult flea fauna (Siphonaptera) was examined in connection with live-trapping studies of the Siberian flying squirrel ( Pteromys volans ) in three study areas in southern Finland between 1997 and 2005.
2. The numerically dominant flea species of the Siberian flying squirrel were Tarsopsylla octodecimdentata octodecimdentata and Ceratophyllus (Monopsyllus) indages indages (Ceratophyllidae); the latter being a host specialist of the Siberian flying squirrel. Tarsopsylla octodecimdentata , which also commonly occurs on the red squirrel ( Sciurus vulgaris ), infected a large proportion of the host population throughout the winter, whereas C. indages occurred predominantly during the summer and autumn, being practically the only flea species in nests during the flying squirrels' breeding season and on juveniles still inhabiting their natal nest.
3. The use of nest boxes by flying squirrels did not have any positive effects on flea populations, but it may have had a negative impact on T.   octodecimdentata .
4. The potentially vulnerable C.   i.   indages is a predictable, widespread component in the flea fauna of the Siberian flying squirrel at various spatial scales, and it is likely to occur in most of the permanent flying squirrel populations in Finland.     

A universal strategy for high-yield production of soluble and functional clostridial collagenases in <Emphasis Type="Italic">E. coli</Emphasis>

Clostridial collagenases are foe and friend: on the one hand, these enzymes enable host infiltration and colonization by pathogenic clostridia, and on the other hand, they are valuable biotechnological tools due to their capacity to degrade various types of collagen and gelatine. However, the demand for high-grade preparations exceeds supply due to their pathogenic origin and the intricate purification of homogeneous isoforms. We present the establishment of an Escherichia coli expression system for a variety of constructs of collagenase G (ColG) and H (ColH) from Clostridium histolyticum and collagenase T (ColT) from Clostridium tetani, mimicking the isoforms in vivo. Based on a setup of five different expression strains and two expression vectors, 12 different constructs were expressed, and a flexible purification platform was established, consisting of various orthogonal chromatography steps adaptable to the individual needs of the respective variant. This fast, cost-effective, and easy-to-establish platform enabled us to obtain at least 10 mg of highly pure mono-isoformic protein per liter of culture, ideally suited for numerous sophisticated downstream applications. This production and purification platform paves the way for systematic screenings of recombinant collagenases to enlighten the biochemical function and to identify key residues and motifs in collagenolysis.