Seasonal and lunar variation in the emergence time of a population of Uca lactea annulipes (Milne-Edwards, 1837) at a shore in Kuwait

This study monitored the endogenous emergence time of the fiddler crab Uca lactea annulipes (Milne-Edwards, 1837) in the field, for the first time, at an intertidal shore in Kuwait, from 1997 to 2001. The results revealed a significant cyclic change in the median emergence time as the season progressed from winter, through spring and summer, to autumn (.44, 1.29, 3.12, and 1.1 h prior to the dead-low tide, respectively). The data also revealed a significant shift in the median emergence time according to moon phase (2.27 h at new moon versus 2.56 h at full moon prior to the dead-low tide).     

Dipole models of alpha-rhythm generators

Different hypothesis of the alpha rhythm origin were tested by dipole simulation of the alpha rhythm sources. EEG was recorded during driving photic stimulation in order to increase the signal-to-noise ratio. Models with fixed and moving dipoles were analyzed. Dipole sources were compared with magnetic resonance imaging (MRI) scans to find the exact location of oscillations in brain anatomical structures. A two-level multiple dipole model was found to fit the EEG most adequately. The first level was represented by two oscillators localized in the thalamic reticular nuclei, and the second level is associated with two modality-specific oscillators localized in the respective cortical areas.     

Gene structure and M20T polymorphism of the Schistosoma mansoni Sm14 fatty acid-binding protein. Molecular,functioanl, and immunoprotection analysis

The Schistosoma mansoni Sm14 antigen belongs to the fatty acid-binding protein family and is considered a vaccine candidate against at least two parasite worms, Fasciola hepatica and S. mansoni. Here the genomic sequence and the polymorphism of Sm14 have been characterized for the first time. We found that the conserved methionine at position 20 is polymorphic, being exchangeable with threonine (M20T). To evaluate the function of the amino acid residue at this position, we have also constructed the mutant Sm14-A20 besides the two native isoforms (Sm14-M20 and Sm14-T20). The three purified recombinant His(6)-tagged Sm14 proteins (rSm14-M20, rSm14-T20, and rSm14-A20) present a predominant beta-barrel structure as shown by CD spectroscopy. Thermal and urea unfolding studies evidenced a higher structural stability of rSm14-M20 over the other forms (rSm14-M20>rSm14-T20>rSm14-A20). All of the Sm14 proteins were able to bind 11-(dansylamino)undecanoic acid (DAUDA) without substantial difference in the binding affinity. However, rSm14-M20 exhibited a higher affinity for natural fatty acids than the rSm14-T20 and rSm14-A20 proteins as judged by competitive experiments against DAUDA (rSm14-M20>rSm14-T20>rSm14-A20). The rSm14-M20 or rSm14-T20 isoforms but not the rSm14-A20 mutant was able to induce significant protection against S. mansoni cercariae challenge in immunized mice. The level of protection efficacy correlates with the extent of structure stability of the recombinant Sm14 isoforms and mutant.     

High level expression of His-tagged colicin pore-forming domains and reflections on the sites for pore formation in the inner membrane

There exists ample evidence for the assumption that pore-forming colicins cannot exert their toxicity within the producing cell and that they must gain access to the outer face of the cytoplasmic membrane to achieve this. We wished to construct pET-vectors to produce pore-forming domains of colicin A and N with N-terminal hexa-histidine tags under the control of a T7 promoter. This was only possible when the correct immunity protein was also present. Hence it appears that this system exhibits the peculiarity that there is a toxicity associated with the over produced pore-forming domain. However, when the ratio of colicin to immunity protein is compared it is still clear that direct insertion into the cytoplasmic membrane does not occur and that membrane translocation of the colicin at limited sites may be occurring. This article reviews previous literature on the subject in terms of a model for limited sites of colicin action.     

Intrinsic processing in the mammalian superior colliculus

The mammalian superior colliculus receives visual inputs from the retina and primary visual cortex in its superficial layers and sends descending motor commands from its deeper layers. It is now becoming clear that a connection exists between these layers, but the signal transmission through it is not robust. The induction of burst discharges in the deeper layer neurons by direct visual inputs from the superficial layers may lead to 'express' saccadic eye movements with extremely short reaction times in behaving animals.     

A satellite DNA element specific for roe deer (Capreolus capreolus)

An abundant tandem repetitive DNA segment (CCsatIII) with a repeat unit of 2.2 kb has been found in the genome of roe deer (Capreolus capreolus). It accounts for approximately 5%–10% of the genome and is only present in the two species of the genus Capreolus. The sequence has no similarity or common motifes with other deer satellite DNAs and there is no internal repeat structure. A 93 bp fragment is homologous to a bovine repeat. Fluorescent in situ hybridisation showed a predominant centromeric staining of most chromosomes accompanied by a weak interstitial staining of the same chromosomes. On Southern blots, CCsatIII probes do not discriminate between the closely related Capreolus species. Received: 16 June 1997; in revised form: 5 December 1997 / Accepted: 8 December 1997     

Stabilisation of immunoconjugates by trehalose

Stable immunoconjugates were prepared in the presence of 400 mM trehalose. Their residual activity after freeze-drying, rehydration and incubation for 9 h at 40?°C was 35%. Freeze-dried conjugates containing 400 mM trehalose incubated at 40?°C for 4 days retained 80% of their original activity.     

The Strong Selective Sweep Candidate Gene ADRA2C Does Not Explain Domestication Related Changes In The Stress Response Of Chickens

Analysis of selective sweeps to pinpoint causative genomic regions involved in chicken domestication has revealed a strong selective sweep on chromosome 4 in layer chickens. The autoregulatory α-adrenergic receptor 2C (ADRA2C) gene is the closest to the selective sweep and was proposed as an important gene in the domestication of layer chickens. The ADRA2C promoter region was also hypermethylated in comparison to the non-selected ancestor of all domesticated chicken breeds, the Red Junglefowl, further supporting its relevance. In mice the receptor is involved in the fight-or-flight response as it modulates epinephrine release from the adrenals. To investigate the involvement of ADRA2C in chicken domestication, we measured gene expression in the adrenals and radiolabeled receptor ligand in three brain regions comparing the domestic White Leghorn strain with the wild ancestor Red Junglefowl. In adrenals ADRA2C was twofold greater expressed than the related receptor gene ADRA2A, indicating that ADRA2C is the predominant modulator of epinephrine release but no strain differences were measured. In hypothalamus and amygdala, regions associated with the stress response, and in striatum, receptor binding pIC50 values ranged between 8.1–8.4, and the level was not influenced by the genotyped allele. Because chicken strains differ in morphology, physiology and behavior, differences attributed to a single gene may be lost in the noise caused by the heterogeneous genetic background. Therefore an F₁₀ advanced intercross strain between White Leghorn and Red Junglefowl was used to investigate effects of ADRA2C alleles on fear related behaviors and fecundity. We did not find compelling genotype effects in open field, tonic immobility, aerial predator, associative learning or fecundity. Therefore we conclude that ADRA2C is probably not involved in the domestication of the stress response in chicken, and the strong selective sweep is probably caused by selection of some unknown genetic element in the vicinity of the gene.     

High cryptic diversity and persistent lineage segregation in endemic Romecytheridea (Crustacea,Ostracoda) from the ancient Lake Tanganyika (East Africa)

Ostracods form a substantial part of the endemic fauna of ancient lakes. Here, we have investigated the phylogenetic and phylogeographic patterns and genetic diversities of species of the endemic genus Romecytheridea from the Southern and Central part of Lake Tanganyika. We found that ostracod populations from four different localities are genetically highly differentiated from each other when analyzing the mitochondrial 16S region, while they are almost identical with genetic markers from the nuclear genome (D1-D2 from the large ribosomal subunit (LSU) and ITS). The criteria of the K/θ method for the evolutionary species concepts are fulfilled when analyzing 16S DNA sequence data, indicating that these populations are in fact different (cryptic) species with allopatric distribution. We discuss various hypotheses on how this high diversity could have originated. The complete lineage segregation can partly be explained by geographic isolation during periods of low lake level stands. But, other factors must have contributed to genetic isolation and speciation, as the two closest populations (Chimba and Katoto) from shallow parts of the Southern basin of Tanganyika are also geographically fully segregated.