Spatial patterns in at-sea behaviour during spring migration by little gulls ( Larus minutus ) in the southeastern North Sea

At-sea distribution of seabirds has been studied on different scales and with different focus in many parts of the world. However, factors and/or processes causing certain patterns are often not easily explained. This also holds true for fast migrating species of international conservation concern, such as the little gull (Larus minutus) in the German Bight (southeastern North Sea). In this study, we used multiyear distributional data in combination with behavioural observations and food sampling to investigate spatial and temporal patterns and their possible causes during spring migration. The results show a highly focussed migration pattern during the last week of April and the first week of May. The river Eider seemed to play an important role as main migration route. Highest numbers were found either close to the mainland or close to the offshore islands. Little gulls used certain subareas for intense feeding (i.e. the region near Helgoland and the outlet of river Elbe) and others for migration. Hydrographic phenomena such as fronts and foam lines play an important role within the feeding sites and strongly influence behaviour and distribution. Feeding behaviour as well as samples of probable prey revealed different quality of feeding sites according to the energy density of the most abundant probable food items (drowned insects versus zooplankton and fish). In conclusion, the area utilisation of L. minutus during spring migration in the German Bight showed a clear pattern, and sites with main feeding action should be regarded as sensitive for little gulls, at least during spring migration.     

Linkage and Association Between CA Repeat Polymorphism of the TNFR2 Gene and Obesity Phenotypes in Two Independent Caucasian Populations

Previously, our group has reported a suggestive linkage evidence of 1p36 with body mass index (BMI) (LOD = 2.09). The tumor necrosis factor receptor 2 (TNFR2) at 1p36 is an excellent positional and functional candidate gene for obesity. In this study, we have investigated the linkage and association between the TNFR2 gene and obesity phenotypes in two large independent samples, using the quantitative transmission disequilibrium tests (QTDT). The first group was made up of 1 836 individuals from 79 multi-generation pedigrees. The second group was a randomly ascertained set of 636 individuals from 157 US Caucasian nuclear families. Obesity phenotypes tested include BMI, fat mass, and percentage fat mass (PFM). A significant result (P = 0.0056) was observed for linkage with BMI in the sample of the multigenerational pedigrees. Our data support the TNFR2 gene as a quantitative trait locus (QTL) underlying BMI variation in the Caucasian populations.     

Effect of endurance flight on haematocrit in migrating birds

The effects of an endurance flight on the haematocrit, the percentage of packed red blood cells per blood volume, were examined within the framework of six possible factors explaining possible changes in the haematocrit. Two approaches were adopted: (1) the haematocrit was studied in four species of passerine birds which landed on an Italian island after having crossed the Mediterranean Sea on their spring migration in a non-stop flight; (2) the haematocrit was evaluated in six individual red knots after a flight of 1, 2, 4 and 10 h in a wind tunnel and the data thus obtained compared with data on resting birds with or without food. In the four passerine species, the haematocrit decreased from 51% in fat birds to 48% in lean birds. In lean birds, the haematocrit dropped from 48% in birds with well-developed breast muscles to 36% in birds with emaciated breast muscles. In the red knots, the haematocrit was dependent on body mass in flying and resting birds. The haematocrit decreased from about 51% pre-flight to about 49% within 1 h of flight and remained at this level for up to 10 h of flight. Taking the results from the passerines and the red knots together, it seems that the haematocrit drops by a few percentage points within 1 h after the onset of flight, decreases very slowly with decreasing body mass and decreases more steeply in very lean birds having entered stage III of fasting. This indicates that dehydration is not an underlying factor in decreased haematocrit because if this were the case we would expect an increase with endurance flight. We found no effect of the presence of blood parasites on haematocrit. With the onset of flight, haemodilution may be adaptive, because it reduces blood viscosity and, thereby, energy expenditure by the heart, or it may be a sign of water conservation as an insurance against the risk of dehydration during long non-stop flights. During endurance flight, a reduction in the haematocrit may be adaptive, in that oxygen delivery capacity is adjusted to the decreased oxygen needs as body mass decreases. A decreasing haematocrit would also allow birds to reduce heart beat frequency and/or heart size, because blood viscosity decreases disproportionally with decreasing haematocrit. However, when energy stores are about to come to an end and birds increase protein breakdown, the haematocrit decreases even further, and birds probably become anaemic due to a reduced erythropoiesis.     

Urban brownfields as temporary habitats: driving forces for the diversity of phytophagous insects

In urban brownfields (derelict sites), we studied the influence of local factors (successional age, vegetation structure, soil) and landscape context (spatial arrangement of brownfields of different successional stages) on the diversity of phytophagous insects, grasshoppers and leafhoppers (Orthoptera and Hemiptera: Auchenorrhyncha). The study was conducted on a total of 246 plots in the cities of Bremen and Berlin, Germany. We used a habitat modelling approach, enabling us to predict the community from single species models (30 species in Bremen, 28 in Berlin).
The results revealed that communities were predominantly determined by vegetation structure, followed by landscape context, soil parameters and site age. For most species, local factors were the most important. Only few species were strongly influenced by landscape context, even though some showed clear negative reactions to low proportions of brownfields in the surroundings.
Along a successional gradient of vegetation structure, from scarce and low to dense and high vegetation, the insect community was not static. Even though species numbers remained comparatively constant, species composition changed considerably. Many species showed clear preferences for certain successional stages. Thus, maintaining the regional species pool of a city requires a mosaic of all successional stages.     

A novel numerical optimization algorithm inspired from weed colonization

This paper introduces a novel numerical stochastic optimization algorithm inspired from colonizing weeds. Weeds are plants whose vigorous, invasive habits of growth pose a serious threat to desirable, cultivated plants making them a threat for agriculture. Weeds have shown to be very robust and adaptive to change in environment. Thus, capturing their properties would lead to a powerful optimization algorithm. It is tried to mimic robustness, adaptation and randomness of colonizing weeds in a simple but effective optimizing algorithm designated as Invasive Weed Optimization (IWO). The feasibility, the efficiency and the effectiveness of IWO are tested in details through a set of benchmark multi-dimensional functions, of which global and local minima are known. The reported results are compared with other recent evolutionary-based algorithms: genetic algorithms, memetic algorithms, particle swarm optimization, and shuffled frog leaping. The results are also compared with different versions of simulated annealing — a generic probabilistic meta-algorithm for the global optimization problem — which are simplex simulated annealing, and direct search simulated annealing. Additionally, IWO is employed for finding a solution for an engineering problem, which is optimization and tuning of a robust controller. The experimental results suggest that results from IWO are better than results from other methods. In conclusion, the performance of IWO has a reasonable performance for all the test functions.     

Membrane-spanning domain of bovine foamy virus transmembrane protein having cytotoxicity

Foamy viruses (FVs) have broad cellular tropism infecting vertebrates from fish to human being, which indicates that Env protein has a high capability for membrane fusion. Conservative features in all FV transmembrane (TM) proteins include a region of hydrophobic domain called membrane-spanning domain (MSD), which contains several stretches of hydrophobic amino acids. To investigate whether these features were associated with the cytotoxicity effect of TM on Escherichia coli, a series of mutants were constructed and expressed in the E. coli BL21 (DE3) using pET-32a (+) as expressing vector. The results showed that only TM3 without MSD was expressed in E. coli, whereas the other two containing full or part of the MSD (TM1 and TM2) could not be expressed. Furthermore, the bacterial amount and living bacteria analysis revealed that the cytotoxicity of TM was dependent on its MSD, especially on the stretches of hydrophobic amino acids. Western blotting analysis showed that TM3 protein was purified with affinity purification. __________ Translated from Acta Scientiarum Naturalium Universitatis Nankaiensis, 2005, 38(2): 49–53 [译自: 南开大学学报 (自然科学版), 2005, 38(2): 49–53]     

Species composition and correlation of understory woody plants in Chinese fir plantation in the lower subtropical area

There are 71 species in the shrub layer of the Cunninghamia lanceolata plantation after natural succession. The species richness and diversity have increased with slight anthropogenic disturbance. The status and function of understory woody species were judged by the analysis of the important value (IV). x ² statistics and r test were used for testing the significance of interspecific association and correlation among 25 main understory woody plants selected from the woody population. The results clearly showed their interspecific relationships and their differences in resource utilization. Species-pairs of positive association were in the majority. Most species were accommodated in the shady habitat. There was a positive correlation between the IV of the species and the interspecific association. The higher the IV of the species, the closer and more significant was the interspecific association. Based on analytical results of interspecific association and correlation, 25 woody plants in the shrub layer could be divided into four ecological species groups: I. Ficus hispida + Antidesma bunius + Mallotus barbatus + Ficus cunia + Saurauia tristyla + Mallotus philippinensis + Maesa japonica + Ficus hirta + Alchornea rugosa + Ficus fulva + Mallotus apelta; II. Cudrania tricuspidata + Schefflera octophylla; III. Cunninghamia lanceolata + Clerodendron cytophyllum + Millettia semicastrata + Randia spinosa + Litsea cubeba + Litsea pungens; IV. Ardisia japonica + Psychotria rubra + Vitex quinata + Cephalanthus occidentalis + Pithecellobium lucidum + Mycetia sinensis. If species group III or II is the advantaged species in the shrub layer, the community would change from a coniferous forest to a sparse evergreen broad-leaved forest. For group IV, the community would be relatively stable. For group I, the coniferous forest would be mixed with coniferous-broad leaved forest. The classification of ecological species groups would provide a theoretical basis on judging its ecological function, adjusting the stand structure of the plantation and directing the suitable natural vegetation type through the close-natural restoration process. __________ Translated from Acta Ecologica Sinica, 2005, 25(9): 2173–2179 [译自: 生态学报, 2005, 25(9): 2173–2179]