Cholinesterases from the marine mussels Mytilus galloprovincialis Lmk. and M. edulis L. and from the freshwater bivalve Corbicula fluminea Müller

In order to improve the molecular basis for the use of bivalve cholinesterases as a reliable biomarker for aquatic pollution, the polymorphism and characterization of these enzymes in Mytilus edulis, Mytilus galloprovincialis and Corbicula fluminea were investigated. All results are consistent with the presence of only one pharmacological form of cholinesterase in each species. The molecular masses were 180 kDa for the two marine mussels and 240 kDa for C. fluminea. The cholinesterases are anchored to the membrane by a glycosyl inositol phosphate like the G^a form (type I) described in vertebrates. Surprisingly, these cholinesterases were poorly inhibited by organophosphorous compounds compared to enzymes from other sources. This suggests that these bivalves could be used as a biomarker for acute rather than chronic contaminations by anticholinesterase insecticides.     

Conservation and status of the fish communities inhabiting the Río Conchos basin and middle Rio Grande,México and U.S.A.

The Chihuahuan Desert region contains a numberof unique aquatic environments, but with fewexceptions, these have been little studied. Because of the dearth of information aboutthese environments and because many of the fishin the region are threatened with extinction orhave gone extinct, we sampled the RíoConchos basin and adjoining aquatic habitats inthe Rio Grande to assess the status of the fishof this region. Most sites showed some degreeof human-induced impacts. A number ofpotentially threatened fish were eitherabundant at only a few sites or rare or absentthroughout the localities sampled. Withoutconcerted binational efforts to conserve thefish of the region, further deletions to thenative fish fauna will likely occur.     

Reply To-Healy D. and Waterhouse J.M.: the Circadian System and Affective Disorders: Clocks or Rhythms? Chronobiologic Disorders, Social Cues and the Light-Dark Cycle

In their monograph (1), Healy and Waterhouse quite thoughtfully distinguish between the altered shapes of circadian rhythms and their entrainment (synchronization). Although there is a great deal of evidence that various influences can alter the shape of circadian rhythms (“masking”), the literature on multiple time cues (zeitgebers) entraining different pacemakers is less convincing. In humans, evidence for nonphotic (social and activity-rest cycle) zeitgebers is restricted to human studies of anchor sleep (2), to data from Wever (3) and Czeisler (4) and to animal studies by Mrosovksy (5) and Turek (6). Until proven otherwise, it seems most likely that social cues primarily affect the sleep-wake cycle (activity-rest cycle), which- being loosely coupled to the endogenous circadian pacemaker-can be dissociated from it and the overt rhythms that are driven by it.     

Flight of the honey bee. VIII. Functional elements and mechanics of the “flight motor” and the wing joint – one of the most complicated gear-mechanisms in the animal kingdom

The form and position of the sclerites and important parts of the thorax, as well as the insertion points of the flight muscles, are described in this study with the help of three-dimensional drawings and electron micrographs. Morphological studies are used for functional analysis of the wing joint and flight muscles, and a three-dimensional model of the wing joint of a honey bee is used to demonstrate the automatic forced guidance of the forewings during the upstroke and downstroke. Accepted: 4 February 1998     

A contribution to the knowledge of the pteridosperm genera Pseudomariopteris Danzé-Corsin nov. emend. and Helenopteris nov. gen

The macromorphology and epidermal anatomy of three Late Carboniferous-Early Permian pteridosperm species, conventionally assigned to the form-genus Pseudomariopteris Danzé-Corsin, are described from the Stephanian of the Blanzy-Montceau Basin (Central France). The generic diagnosis of Pseudomariopteris is emended, and P. busquetii is designated as the type species of the genus. The combination P. cordato-ovata (Weiss) Gillespie et al. is validated to replace the illegitimate name P. ribeyronii (Zeiller) Danzé-Corsin. The species diagnoses of P. busquetii and P. cordato-ovata are emended. On the basis of its epidermal anatomy, P. paleaui, another species orininally described from Central France, is transferred to the newly established genus Helenopteris Krings et Kerp, and the new combination Helenopteris paleaui is introduced. Lectotypes of P. busquetii and H. paleaui are selected. In addition, specimens from other basins are (re-)examined and illustrated. Seeds attached to a P. busquetii specimen suggest a callistophytalean relationship for Pseudomariopteris. Compression fossils and cuticles of Pseudomariopteris and Helenopteris are interpreted in terms of palaeoecology: Pseudomariopteris busquetii and P. cordato-ovata had climbing/scrambling growth habits; specialized climber hooks can be demonstrated for both species, either in compression or in cuticular preservation. Although the growth habit of H. paleaui is not yet entirely clear, the size of its fronds suggests that this taxon most probably was also a scrambler/climber. Finally, based on epidermal features, a tentative reconstruction of stages of the pinnule ontogeny of H. paleaui is provided.     

Nucleosides and Nucleotides. 104. Radical and Palladium-Catalyzed Deoxygenation of the Allylic Alcohol Systems in the Sugar Moiety of Pyrimidine Nucleosides§,1

Abstract

New methods for the synthesis of 2′,3′-didehydro-2′,3′-dideoxy-2′ (and 3′)-methyl-5-methyluridines and 2′,3′-dideoxy-2′ (and 3′)-methylidene pyrimidine nucleosides have been developed from the corresponding 2′ (and 3′)-deoxy-2′ (and 3′)-methylidene pyrimidine nucleosides. Treatment of a 3′-deoxy-3′-methylidene-5-methyluridine derivative 8 with 1,1′-thiocarbonyldiimidazole gave the allylic rearranged 2′,3′-didehydro-2′,3′-dideoxy-3′-[(imidazol-1-yl)carbonylthiomethyl] derivative 24. On the other hand, reaction of 8 with methyloxalyl chloride afforded 2′-O-methyloxalyl ester 25. Radical deoxygenation of both 24 and 25 gave 26 exclusively. Palladium-catalyzed reduction of 2′,5′-di-O-acetyl-3′-deoxy-3′-methylidene-5-methyluridine (32) with triethylammonium formate as a hydride donor regioselectively afforded the 2′,3′-dideoxy-3′-methylidene derivative 35 and 2′,3′-didehydro-2′,3′-dideoxy-3′-methyl derivative 34 in a ratio of 95:5 in 78% yield. These reactions were used on the corresponding 2′-deoxy-2′-methylidene derivatives. An alternative synthesis of 2′,3′-dideoxy-2′-methylidene pyrimidine nucleosides (43, 52, and 54) was achieved from the corresponding 1-(3-deoxy-β-D-thero-pentofuranosyl)pyrimidines (44 and 45). The cytotoxicity against L1210 and KB cells and inhibitory activity of the pathogenicity of HIV-1 are also described     

Chronostratigraphy and the Palaeoenvironment of the Bistrița Valley. New Interpretations and a Critical Retrospective Evaluation

The Carpathian Arch was certainly a difficult obstacle for the Palaeolithic communities of Eastern and Central Europe, at least during certain stages of the Upper Pleistocene glaciation, such as the Last Glacial Maximum. The density and perennity of the Palaeolithic occupations in the Bistri?a Valley were favoured by the propitious conditions of living and developing long-term survival strategies. The importance of the Bistri?a Valley lies in the fact that it is strongly embedded in the mountainous landscape, with a route extended in the Sub-Carpathian area and a generous opening towards the east to the plateau region and further towards the Great Russian Plain. The Bistri?a Valley is a landmark of the Romanian Palaeolithic due to the number of investigated Palaeolithic settlements, the wealth and variety of archaeological materials and the extensive interdisciplinary studies. All this has entailed a better assessment of the evolution of the palaeoenvironment and of the chronostratigraphy of the Palaeolithic occupations. In a matter of speaking, the Bistri?a Valley is to Romania what the Vézère Valley is to the Dordogne region in France.     

L. plantarum,L. fermentum,and B. breve Beads Modified the Intestinal Microbiota and Alleviated the Inflammatory Response in High-Fat Diet–Fed Mice

Probiotics and Antimicrobial Proteins - This paper aims to study the effects of compound microbe-based beads on changes in the intestinal microbiota and alleviation of high-fat (HF)...     

Why are autism and the fragile-X syndrome associated? Conceptual and methodological issues.

Investigations of the association between autism and the fragile-X syndrome have yielded conflicting results with some studies indicating a strong correlation and others indicating no relation between the disorders. In this paper, we review the relevant research on this controversy and discuss the conceptual and methodological problems involved in such an inquiry. We conclude that autism and fragile X are associated and that this relation will prove fruitful in understanding the role of the X chromosome in a variety of behavior disorders and in unraveling various theoretical accounts on the etiology of autism.     

Pyrenomycetes of the Russian Far East—Additions and corrections. 1.Rossmania ukurunduensis gen. et sp. nov.

Rossmania ukurunduensis gen. and sp. nov. collected in the reverve Bolshekhekhtsirsky (Khabarovsk Territory, Russian Far East) is described and illustrated.Rossmania aculeata comb. Nov. is indicated as the second species of the genus.     

Biotechnology education and the training of engineer-technologists in the St. Petersburg State Chemical–Pharmaceutical Academy and the State University of Technology and Design

Some facts about biotechnological education in St. Petersburg (Russia) are presented by authors at two different higher schools: the State Chemical–Pharmaceutical Academy and the State University of Technology and Design.     

Rabbit β-glucuronidase. Purification and properties, and the existence of multiple forms

1. beta-Glucuronidase (EC 3.2.1.31) was purified from rabbit liver by a procedure involving autolysis, (NH(4))(2)SO(4) fractionation, chromatography on DEAE-cellulose and hydroxyapatite, gel filtration, sedimentation in a sucrose gradient, and isoelectric focusing. 2. Electron microscopy revealed ferritin as the major contaminant in later stages of purification and also showed aggregates of enzyme molecules. Particular attention was paid to the removal of ferritin. 3. The purified enzyme was homogeneous in polyacrylamide-gel electrophoresis both in non-dissociating conditions and in the presence of sodium dodecyl sulphate, and in Ouchterlony gel diffusion and immunoelectrophoresis against polyspecific antisera. 4. Sedimentation in sucrose gradients gave a molecular weight of 300000, whereas gel filtration indicated 440000. 5. Subunits of 75000 molecular weight were observed in gel electrophoresis in the presence of sodium dodecyl sulphate and in gel filtration in the presence of urea. 6. The K(m) value for p-nitrophenyl beta-d-glucuronide was 0.6mm, and the enzyme was extremely sensitive to lactone inhibitors. It was also inhibited by Hg(2+) ions. 7. Multiple forms were observed in the pure enzyme by isoelectric focusing, with pI values of 4.5-5.8. Subunits showed similar heterogeneity. The origin of the multiple forms was investigated in detail, and the possibility of artifact generation largely excluded. Some of the forms of lowest pI disappeared after neuraminidase digestion. The nature of the residual heterogeneity remains to be elucidated.     

Nodulation and nitrogen-fixation byHippophaë rhamnoides L. in the field

Summary 1. The extent of nodulation and nitrogen fixation by a population ofHippophaë rhamnoides bushes occurring on a sand dune system on the east coast of England has been studied.2. Nodules were found on all plants (the latter ranged from 3 to 16 years in age) and using the isotope N¹⁵ it was confirmed that these nodules fixed nitrogen. The nodules on the youngest plants were most active in fixation but because of the greater total nodule mass older plants fixed the largest quantities of nitrogen.3. Large increases in total nitrogen (i.e. soil plus plant nitrogen) occurred with increase in age of the plants, such nitrogen increases ranging from 27 kg per hectare per annum in the presence of bushes 0 to 3 years old to 179 kg per hectare per annum in the presence of bushes 13 to 16 years old.4. The N¹⁵-technique indicated that a proportion of the nitrogen accumulated was due to fixation byHippophaë but nitrogen contributions from other sources could not be ruled out.5. The levels of nitrate-nitrogen and ammonium-nitrogen in the soil underHippophaë showed a marked seasonal variation, increasing to a maximum in the winter and to a minimum in the summer. These levels were in general inversely related to the level of average monthly rainfall. Because of the low levels of combined nitrogen in the soil during the summer months it seems unlikely that combined nitrogen should markedly inhibit fixation in this situation.