Population dynamics, distribution patterns and life cycles of Neobisium muscorum and Chthonius orthodactylus (Pseudoscorpiones: Arachnida)

The population dynamics, life cycles and distribution patterns of Neobisium muscorum (Leach) and Chthonius orthodactylus (Leach) were studied over a two year period in a Chiltern beechwood site. The data obtained for the two species are compared, and the importance of pseudoscorpions in the beechwood community is discussed.     

Food provision to nestlings in the Hoopoe Upupa epops: implications for the conservation of a small endangered population in the Swiss Alps

In an attempt to recognize the possible ecological causes of the decline of a population of Hoopoes Upupa epops in the Swiss Alps, we collected data on resource exploitation. The prey provisioned to nestlings by parents was investigated at four breeding sites using photographs (n = 4353, 80% of which enabled prey identification). Molecrickets Gryllotalpa gryllotalpa and Lepidoptera (larvae and pupae) were dominant in nestling diet (93% frequency; 97% biomass). Although Molecrickets were provisioned less frequently (26%) than Lepidoptera (67%), they represented 68% of the total biomass (vs 29% for Lepidoptera). There was an overall negative relationship between the proportion of Molecricket biomass in the diet and the parents' feeding rate, whereas a comparison between broods showed that a higher provisioning activity did not lead to an increase in the biomass supplied to the chicks. A diet based on Molecrickets therefore appears to be energetically advantageous. As Molecrickets are a traditional prey of Hoopoes in central Europe, this might be relevant to other populations. In the study area, Molecrickets occur only on the intensively cultivated plain, whereas the majority of Hoopoe pairs nest at various altitudes on the foothills adjacent to the plain as the latter provides at present almost no suitable nesting sites. Hoopoes breeding higher up on the foothills seem to experience greater provisioning costs and have, on average, lower breeding success. Providing nest sites on the plain is the main conservation measure proposed for the local Hoopoe population. Further attention should also be paid to Molecrickets as these may be crucial for Hoopoes.     

Evaluation of a green laser pointer for flow cytometry.

Flow cytometers typically incorporate expensive lasers with high-quality (TEM00) output beam structure and very stable output power, significantly increasing system cost and power requirements. Red diode lasers minimize power consumption and cost, but limit fluorophore selection. Low-cost DPSS laser pointer modules could possibly offer increased wavelength selection but presumed emission instability has limited their use. A $160 DPSS 532 nm laser pointer module was first evaluated for noise characteristics and then used as the excitation light source in a custom-built flow cytometer for the analysis of fluorescent calibration and alignment microspheres. Eight of ten modules tested were very quiet (RMS noise < or = 0.6% between 0 and 5 MHz). With a quiet laser pointer module as the light source in a slow-flow system, fluorescence measurements from alignment microspheres produced CVs of about 3.3%. Furthermore, the use of extended transit times and < or =1 mW of laser power produced both baseline resolution of all 8 peaks in a set of Rainbow microspheres, and a detection limit of <20 phycoerythrin molecules per particle. Data collected with the transit time reduced to 25 micros (in the same instrument but at 2.4 mW laser output) demonstrated a detection limit of approximately 75 phycoerythrin molecules and CVs of about 2.7%. The performance, cost, size, and power consumption of the tested laser pointer module suggests that it may be suitable for use in conventional flow cytometry, particularly if it were coupled with cytometers that support extended transit times.     

K-way neural network graph partitioning with separator vertices

A neural network for partitioning graphs into any number of subgraphs using a k-way procedure is presented. The resulting neural network optimises all subgraphs so that they contain approximately the same number of vertices with the exception of a `separator' subgraph. The latter separates all the other subgraphs and is optimised to contain a minimum number of vertices. Expressions for the neuron link weights for such a network are derived analytically, and the recall mechanism of the mean field theorem neural network is used to obtain the graph partitioning. Applications focus on partitioning graphs associated with finite element meshes which, together with parallel domain decomposition solution methods, provide the motivation for this work. Received: 14 January 1998 / Accepted in revised form: 24 November 1998     

Cyclic Expression of A Nuclear Protein In A Dinoflagellate

Nuclei of the dinoflagellate Crypthecodinium cohnii strain Whd were isolated and nuclear proteins were extracted in three fractions, corresponding to the increasing affinity of these proteins to genomic DNA. One fraction contained two major bands (48- and 46-kDa) and antibodies specific to this fraction revealed two major bands by Western blot on nuclear extracts, corresponding to the 46- and 48-kDa bands. The 48-kDa protein was detected in G1 phase but not in M phase cells. An expression cDNA library of C. cohnii was screened with these antibodies, and two different open reading frames were isolated. Dinoflagellate nuclear associated protein (Dinap1), one of these coding sequences, was produced in E. coli and appeared to correspond to the 48-kDa nuclear protein. No homologue of this sequence was found in the data bases, but two regions were identified, one including two putative zinc finger repeats, and one coding for two potential W/W domains. The second coding sequence showed a low similarity to non-specific sterol carrier proteins. Immunocytolocalization with specific polyclonal antibodies to recombinant Dinap1 showed that the nucleus was immunoreactive only during the G1 phase: the nucleoplasm was immunostained, while chromosome cores and nuclear envelopes were negative.     

Unexpected ratio of allozyme expression in diploid and triploid individuals of the clonal hybrid fish Phoxinus eos-neogaeus.

Phoxinus eos-neogaeus, a North American freshwater fish, was formed by hybridization between P. neogaeus and P. eos. Individuals of P. eos-neogaeus express one allozyme of P. eos and one allozyme of P. neogaeus for enzymes for which the parental allozymes are distinctive. We performed densitometry on phosphoglucomutase (PGM) and one glucose-6-phosphate isomerase locus (GPI-A) separated by cellulose acetate electrophoresis to determine if the parental species' allozymes are expressed in proportion to the number of genomes present in diploid and triploid individuals, and if these enzymes are regulated separately in different tissues. In diploids, activity of the P. eos allozyme was greater than the P. neogaeus allozyme in eye, liver, and muscle but not in heart (one sample t-test, P = 0.05) for PGM. The activity of the P. eos GPI-A allozyme was significantly greater than the P. neogaeus allozyme in heart, eye and muscle but not in liver (one sample t-test, P = 0.05). The expected ratio of eos:neogaeus expression in triploid P. eos-neogaeus x eos individuals is 2:1. For PGM, the observed ratio of eos:neogaeus expression was not significantly different from 2:1 in all four tissues. The P. eos allozyme for GPI was expressed less than expected in all four tissues (one-sample t-test, P = 0.05). Thus, greater than expected expression of the P. eos allozyme was not observed in triploid individuals as it was in the diploids. These data show that PGM and GPI are regulated separately, and that regulation differs by tissue, and in fish of distinct ploidy levels. J. Exp. Zool. 284:663-674, 1999.     

Large-scale identification of polymorphic microsatellites using an <Emphasis Type="Italic">in silico</Emphasis> approach

Background  

Simple Sequence Repeat (SSR) or microsatellite markers are valuable for genetic research. Experimental methods to develop SSR markers are laborious, time consuming and expensive. In silico approaches have become a practicable and relatively inexpensive alternative during the last decade, although testing putative SSR markers still is time consuming and expensive. In many species only a relatively small percentage of SSR markers turn out to be polymorphic. This is particularly true for markers derived from expressed sequence tags (ESTs). In EST databases a large redundancy of sequences is present, which may contain information on length-polymorphisms in the SSR they contain, and whether they have been derived from heterozygotes or from different genotypes. Up to now, although a number of programs have been developed to identify SSRs in EST sequences, no software can detect putatively polymorphic SSRs.