An evaluation of electrophoresis as a taxonomic method using comparative data from the macropodidae (Marsupialia)

Comparative electrophoretic data collected for seven proteins from thirty-four species of marsupial have been examined to define the advantages and shortcomings of electrophoresis as a taxonomic method. The problems of relative rates of change, convergence and parallelism are examined and the range of taxonomic ranks which can usefully be studied with this technique is determined. The relative merits of this type of data, when combined with various methods of taxonomic analysis, are discussed.     

Fine structure and classification of shrimp hemocytes

The structure of hemocytes from two species of penaeid shrimp was examined by light and electron (TEM) microscopy. Hemocytes from the two species are indistinguishable and are classified as either agranular, small-granule, or large-granule hemocytes. Agranular hemocytes are the smallest of the hemocytes, lack granules, compose only 5–10% of the circulating hemocytes, and are nonrefractile when examined by light microscopy. Small-granule hemocytes are the most abundant type of hemocyte (75% of all hemocytes), appear nonrefractile, and contain a variable number (1–40) of granules (0.4 μm diameter). Large-granule hemocytes compose 10–20% of the hemocytes. They are filled with granules (0.8 μm in diameter) that are highly refractile when examined by light microscopy and are electron-dense when examined by TEM. Our classification scheme is based solely on the absence or presence and relative size of granules. Features used by other researchers, such as cell size, shape, and staining properties, were not used because these features are subtle and/or subjective. The proposed classification is compared with schemes developed for other decapods, and its usefulness and limitations are discussed. This scheme will serve as a basis for further studies on the maturation and physiological function(s) or crustacean hemocytes.     

Fine Structure of Vibrio cholerae During Toxin Production

The fine structural changes associated with cell growth and toxin production have been examined in Vibrio cholerae strain 569B. No morphological alterations in the cell envelope are apparent during logarithmic growth with thin-section techniques. However, internal swelling, suggesting alteration of cell envelope permeability, is evident particularly during the late logarithmic and early stationary phases of growth. Certain extracellular material demonstrable with negative-stain techniques does appear during the period of toxin production. The possible origin of this material is discussed. The effects of high temperature (37 C) and aeration on cell structure are also examined.     

Protein modified- and membrane electrodes: strategies for the development of biomolecular sensors

Different procedures used for constructing protein/enzyme-modified electrodes are examined, in particular adsorption, covalent attachment and film deposition. The performances of such modified electrodes with electroactive proteins or enzymes attached to their active surface are examined, especially in the case of c-type cytochromes, hydrogenases and glucose oxidase. Another strategy presented in this review consists of the use of membrane electrodes with an electroactive protein imprisoned between a dialysis membrane and the electrode surface. The versatility and other advantages of such a procedure are underlined. Applications of membrane electrodes to the bioremediation of soils and effluents and as models for investigating interactions between proteins and soils are described.     

The Nuclear Family versus the Men's House? A re-examination of Mundurucú Sociality

It has been posited that in communities with residential men's houses there is perforce no nuclear family. This position is examined with reference to the published data on the Mundurucú of Central Brazil. Comparative data are also examined from Oceania and elsewhere. The conclusion is that the two institutions do indeed co-exist in the Mundurucú case.     

The character of the muscarinic receptors in different regions of the rat brain

The binding characteristics of muscarinic receptors have been critically examined in six regions of the rat brain. The binding curves of antagonists are similar for all six areas but the binding curves of agonists show large differences. It is shown that in all regions there are three classes of receptors with similar binding characteristics but that these are present in different proportions. The binding constants to the three receptor types of a range of agonists were examined and evidence was produced in support of the theory that the subclasses of brain receptors are due to a single receptor subunit subject to different conformational constraints.     

Organization of motoneurones in the prothoracic ganglion of the cockroach Periplaneta americana (L.).

The location within the prothoracic ganglion of neurone somata with axons in identified peripheral nerves is examined by the cobalt iontophoresis technique. Axons are filled with cobalt by diffusion through their cut ends and the cobalt is then precipitated as the black sulphide inside the neurone. It is assumed that neurones with axons in peripheral nerves and somata in central ganglia are either motor or neuro-secretory. Fifteen nerves are examined and maps of the location of somata with axons in each nerve are presented. The axon distribution in peripheral nerves of three common inhibitory neurones is described. Dendritic morphology of one common inhibitory neurone and two coxal depressor motoneurones is illustrated. It is proposed that some individual neurones can be reliably identified from their soma dimensions and location within the ganglion. The number of motoneurones with somata in the prothoracic ganglion and their homology with cells in the other thoracic ganglia are discussed.     

STATISTICAL ANALYSIS OF HETEROZYGOSITY DATA: INDEPENDENT SAMPLE COMPARISONS

The distribution of mean heterozygosities under an infinite allele model with constant mutation rate was examined through simulation studies. It was found that, although the variance of the distribution decreases with increasing numbers of loci examined as expected, the shape of the distribution may remain skewed or bimodal. The distribution becomes symmetrical for increasing mean heterozygosity levels and numbers of loci. As a result, parametric statistical tests may not be valid for making comparisons among populations or species. Independent sample t-tests were examined in detail to determine the frequency of rejection of the null hypothesis when pairs of samples are drawn from populations with the same mean heterozygosity. Differing numbers of loci and levels of mean heterozygosity were examined. For mean heterozygosity levels above 7.5%, t-tests provide the proper rejection rate, with as few as five loci. When mean heterozygosity is as low as 2.5%, the t-test is conservative even when 40 loci are examined in each population. Independent sample t-tests were then examined for their power to detect true differences between populations as the degree of difference and number of loci vary. Although large differences can be found with high certainty, differences on the order of 5% heterozygosity may require that large numbers of loci (>40) be examined in order to be 80% or more certain of detecting them. In addition, it is emphasized that, for small numbers of loci (<25), the statistical detection of differences of interesting magnitude requires that relatively rare sampling events occur and that much larger differences be observed among the samples than exist for the population means. Two reasons exist for the lack of sensitivity of the test procedures. First, when mean heterozygosity levels are low, the non-normality of the sample means is perhaps most important. Second, even when mean heterozygosity levels are high or when sample sizes are large enough so sample means are approximately normally distributed, the intrinsically high interlocus variance of heterozygosity estimates makes the tests insensitive to the presence of heterozygosity differences that might be biologically meaningful. Finally, the implications of the results of this study are discussed with regard to observed low levels of correlation between heterozygosity and other explanatory variables.     

The design of a panel study under an alternating Poisson process assumption.

We discuss the design of a panel study for the estimation of the average durations in the two states of an alternating Poisson process. Two types of designs are examined. The first fixes the number of follow-up waves but permits the total length of follow-up to vary, and the second varies the number of follow-up waves with fixed length. Simple expressions for nearly optimal designs are presented, and we compare these with designs allowing for continuous observation. Both equilibrium and nonequilibrium cases are examined. An example is given using morbidity data to illustrate how these results can be applied.     

The genera Ceratomyxa Thélohan, 1892, Leptotheca Thélohan, 1895 and Sphaeromyxa Thélohan, 1892 (Myxosporea: Bivalvulida) in gadid fish of the Northeast Atlantic

The gall-bladders of four species of gadid fish from the North Sea and Norwegian waters were examined for myxosporeans. The host species were cod Gadus morhua L. (350 examined), haddock Melanogrammus aeglefinus (L.) (592 examined), saithe Pollachius virens (L.) (205 examined) and whiting Merlangius merlangus (L.) (368 examined). Four species of myxosporeans are redescribed from these fish. Ceratomyxa arcuata Thélohan, 1892 was the most common species and was found in whiting (42.8%) and cod (0.6%). Leptotheca informis Auerbach, 1910 was found only in whiting (6.5%). L. longipes Auerbach, 1910 was found only in haddock (6.2%). Sphaeromyxa hellandi Auerbach, 1909 was found in haddock (9.1%) and whiting (0.3%). None of the saithe examined, and no cod or haddock from Norwegian waters, was infected with these myxosporeans. All four species appear to have distributions limited to the Northeast Atlantic, with S. hellandi having a more northern distribution than the other three. The validity of reports of C. arcuata, L. informis and L. longipes from outside this area is discussed.     

The Ecological State of the Waddensea. An Assessment

Since the present quality state of the Wadden Sea is judged more discordantly than that of the North Sea, it is examined whether the Wadden Sea is a separate ecosystem. The nutrient load into the Wadden Sea and the trend of the load are assessed. Biological indicators of the ecological state of the Wadden Sea are examined with the result that there are signs of a bad as well as of a good state. This contradiction is assigned to the fact that quality standards are absent. Self-protection mechanisms of the Wadden Sea are discussed with respect to their responsibility for the relatively good state. A qualitative model is proposed to explain the long-term behaviour of the ecosystem.     

THE ANTI-ESTERASE ACTIVITY OF PARATHION AND SOME RELATED ORGANOPHOSPHORUS COMPOUNDS

The in vitro activity of cholinesterase and acetylesterase of two insect species- Locusta migratoria migratorioides R. &F. and Calandra granaria L.—has been examined.
There appear to be two distinct enzymes present, and in both insects their activities are at comparable levels and their inhibition by the organophosphorus compounds examined are also similar.
Compounds possessing the phosphoryl group have high inhibitory activity and those with the thiophosphoryl group have low activity in vitro.     

Lipids of Candida lipolytica cultivated in n-alkanes by the industrial method ("Toprina")]

The following lipidic classes are examined in the present study: Total Lipids, Phospholipids, Neutral Lipids, Sterols, and Carotenoid Pigments from dried biomasses of Candida lipolytica grown on n-alkanes by industrial process following the BP technique ("Toprina"). The composition of the lipid classes examined in "Toprina" agree generally with bibliographic data about n-alkanes grown Candida lipolytica in batch cultures.     

The effects of the Kielder scheme on fisheries

The scheme is briefly described. The success of the Kielder and Bakethin reservoir fisheries is examined. The poor condition of trout in Kielder reservoir is considered in relation to physical and chemical factors including water turbidity, low nutrient levels and the location of the reservoirs.
The performance of Kielder hatchery and the difficulties of collecting broodstock of Tyne origin are described.
The effects of water releases from Kielder reservoir upon the salmon, Salmo salar L., and brown trout Salmo trutta L., fisheries within the River North Tyne and examined. Aspects considered include modified water temperature regimes, water chemistry and the magnitude and timing of releases for river regulation and generation of hydroelectric power.
The problems associated with fish passage at Riding Mill weir, the point of water transfer to the River Wear and River Tees, are examined and the progress of inter-river transfers is described.     

Measurement of light gradient in plant organs with a fiber optic microprobe

A light fiber optic system for the measurement of the radiation transmittance gradient in the plants organs is described. The radiation of halogen lamp is carried by a light fiber cable, 2 mm thick, into the examined material. Radiation passing through the plant material is mainly absorbed, and partly transmitted to the inner layers of the cells. Radiation transmitted by the plant material falls on the receiving light fiber, 50 m thick, and is carried onto the radiometer. The receiving light fiber, placed in the injection needle, is introduced into the examined material, which enables the measurement of radiation gradient transmittance in the examined material. An example of the utilisation of the measurement system are the results obtained on the leaves and bark of the current-year stems of lilac and on bean pods. The obtained results are in agreement with the distribution of photosynthetic pigments in these organs.     

The levels of soil pollution with plutonium isotopes in the Bryansk Oblast (following the accident at the Chernobyl Atomic Electric Power Station)]

The estimates of plutonium concentration in soils of Western regions of Bryansk (Krasnogorsky, Novozybkovsky, Zlynkovsky and Klintsovsky) are presented. The levels of soil contamination with plutonium within the regions examined vary by 4-5 times, although no definite geographical direction of pollution intensity within the territory examined is noted. The cumulative concentration of isotopes (238Pu, 239Pu, and 240Pu) varies within 21-112 Bq/kg.     

Nephridial and gonoduct distribution patterns in Nerillidae (Annelida: Polychaeta) examined by tubulin staining and cLSM

The distribution and configuration of nephridia and gonoducts are described for seven species from seven genera of the interstitial polychaete family Nerillidae. The ciliated nephridia and gonoducts were identified by tubulin staining and examined with a confocal laser scanning microscope. The following species of the seven to nine-segmented nerillids were examined: Leptonerilla prospera, Nerilla antennata (nine segments); Nerillidium mediterraneum, Trochonerilla mobilis, Gen. sp. A (eight segments); and Aristonerilla brevis, Paranerilla limicola (seven segments). Two of the examined species are hermaphroditic (N. mediterraneum and Gen. sp. A). Segmented nephridia can be found from the first to the last segment, with a total of two to five pairs. One to three pairs of segmented spermioducts are present in all species. One pair of gonoducts is found in all species, except for P. limicola, where they are absent. Nephridia vary in length from half to almost twice the length of a segment and may be curled up in loops. In A. brevis and P. limicola the nephridia are discontinuously ciliated. The distribution and configuration of spermioducts and gonoducts are also variable, although to a lesser extent. The spermioduct distribution is generally consistent within genera and therefore of systematic significance. Nephridia and gonoducts are never found together in the same segments, and the results indicate that gonoducts and nephridia have developed from the same anlagen. The distribution patterns of nephridia and gonoducts are discussed with respect to segmentation, systematics, and development.     

The phylogeny of marine and freshwater caulobacters reflects their habitat.

Caulobacter is a distinctive genus of prosthecate bacteria. Because caulobacters adhere to surfaces and are found in diverse locales, their role in oligotrophic environments and bacterial biofilm communities is of interest. The phylogenetic relationships of a group of marine and freshwater caulobacters were examined in part to address whether the taxonomic grouping of these bacteria (based primarily on morphological characters) was consistent with 16S rRNA sequence divergence. The caulobacters examined (9 marine and 11 freshwater species or strains) were affiliated with the alpha proteobacteria. They made up a diverse yet, with the possible exception of a strain of Caulobacter subvibrioides, coherent assemblage. The diversity was most apparent in a comparison of freshwater and marine isolates; an early divergence within the main caulobacter lineage generally corresponded to strains isolated from freshwater and marine habitats. The marine caulobacter assemblage was not exclusive; it also embraced strains of marine hyphomonads and Rhodobacter capsulatus. We hypothesize that these genera are derived from more ancestral caulobacters. Overall, the data are consistent with the interpretation that all of the caulobacters examined, with the possible exception of C. subvibrioides, are ancestrally related, albeit anciently, and that most often division by terrestrial and marine habitats corresponds to an early evolutionary divergence within the genus.