Preparation of the tritiated molecular forms of gangliosides with homogeneous long chain base composition

Gangliosides G_M2, G_M1 and G_D1b were radiolabelled at C-6 of the terminal galactose orN-acetylgalactosamine by the galactose oxidase/[³H]NaBH₄ method; gangliosides G_M2, G_M1, Fuc-G_M1 and G_D1a were radiolabelled at C-3 of the long chain base by the 2,3-dichloro-5,6-dicyanobenzoquinone/[³H]NaBH₄ method.By application of an original HPLC procedure, eight different molecular species were prepared from each labelled ganglioside. Each of these species was characterized by the presence of one of the following long chain bases:erythro C18 sphingosine,threo C18 sphingosine,erythro C18 sphinganine,threo C18 sphinganine,erythro C20 sphingosine,threo C20 sphingosine,erythro C20 sphinganine andthreo C20 sphinganine.From G_D1b only the species containing theerythro forms of long chain bases were obtained.The individual molecular species were more than 99% homogeneous and had a radiopurity better than 99%. The molecular species of the same ganglioside, radiolabelled at C-3 of the long chain base, had identical specific radioactivity, namely 1.17, 1.25, 0.85 and 1.28 Ci/mmol for G_M2, G_M1, Fuc-G_M1 and G_D1a respectively. The molecular species of the same ganglioside, radiolabelled at C-6 of terminal galactose orN-acetylgalactosamine, had similar specific radioactivity, namely 1.34–1.40, 1.44–1.51, 1.37–1.44 Ci/mmol for G_M2, G_M1 and G_D1b respectively.     

LAS inhibition of diffusion and uptake of tritiated uridine during teleost embryogenesis

Synopsis Fathead minnow embryos (Pimephales promelas Rafinesque) of 5 different developmental ages (5, 33, 48, 72 and 96 hrs after fertilization) were used as controls and exposed for 2 hrs to a solution of 0.25 Ci ml^–1 of³H-Uridine. Another set of embryos (5, 33, 48, 72 and 96 hrs after fertilization) were subjected to the same treatment except that during the one hour immediately preceding the³H-Uridine incubation, the control embryos were placed in water while the experimental embryos were placed in water containing 15 ppm 11.2 LAS. In both cases, radiation counts minute^–1 embryo^–1 and per milligram of embryo increased over the 4 day developmental period. The embryos with LAS treatment displayed lower radiation counts at all ages as compared to controls, indicating an inhibition of diffusion and uptake of³H-Uridine and/or RNA synthesis. The possible mechanism of LAS is discussed.     

Uptake, metabolism, and excretion of injected tritiated 22,33-dihydroazadirachtin in last instar larvae of Heliothis virescens

To evaluate its uptake, metabolism, and excretion, we studied the fate of tritiated 22,23-dihydroazadirachtin, when injected either orally or directly into the hemocoel of last instar larvae of Heliothis virescens (Fabr.). An oral injection of 1.0 g of tritiated 22,23-dihydroazadirachtin, the minimum oral dose necessary to disrupt pupation, was rapidly absorbed through the midgut such that >50% of the radioactivity was detected in the body 1 h post injection. Excretion of radioactivity following an oral injection was slow; 24 to 72 h elapsed before approximately 50% of the radioactivity was detected in the feces. In contrast, excretion of radioactivity following a hemocoel injection of 0.3 g of tritiated 22,23-dihydroazadirachtin, the minimum hemocoel dose necessary to disrupt pupation, was rapid; almost 50% of the radioactivity was detected in the feces only 1 h post injection. Tritiated 22,23-dihydroazadirachtin was metabolized to a more polar compound(s) by H. virescens larvae, as indicated by thin layer chromatography. Metabolism to a more polar form(s) occurred probably following absorption through the midgut, since hemocoel-injected larvae exhibited a more rapid rate of conversion than oral-injected larvae. Even though metabolism to a more polar form(s) should enhance its excretion, approximately 25% of the radioactivity remained in the body 72 h following either oral or hemocoel injection, and this was sufficient to disrupt pupation.

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Résumé L'étude a été réalisée avec de la 22,23-dihydroazadirachtine tritiée injectée soit oralement, soit directement dans l'hémocoele des chenilles de H. virescens Fabr. du dernier stade. La dose orale minimale de 1,0 g, nécessaire pour perturber la nymphose, a été rapidement absorbée à travers l'intestin moyen, d'une façon telle que plus de 50% de la radioactivité a été retrouvée dans le corps une heure après l'injection. L'excrétion de la radioactivité à la suite d'une injection orale a été lente; 24 à 72 heures se sont écoulées avant que 50% de la radioactivité ait été décelée dans les excréments. A l'opposé, l'excrétion de la radio-activité à la suite d'une injection hémocoelique de 0,3 g, — dose hémocoelique minimale pour perturber la nymphose-, a été rapide; presque 50% de la radioactivité a été décelée dans les excréments au bout d'une heure seulement après l'injection. La chromatographie en couche mince a montré que la 22,23-dihydroazadirachtin a été métabolisée en substance(s) plus polaire(s) par les chenilles de H. virencens. La métabolisation en forme(s) plus polaire(s) se produit vraisemblablement après l'absorption à travers l'intestin moyen, puisque les chenilles injectées directement dans l'hémocoele ont présenté un taux de conversion plus rapide que les chenilles injectées oralement. Bien que la métabolisation sous une (des) forme(s) plus polaire(s) ait augmenté l'excrétion, approximativement 25% de la radioactivité subsistait dans le corps 72 heures après une injection orale ou hémocoelique, ce qui est suffisant pour perturber la nymphose.

     

New species and new combinations in Peruvian Orchidaceae

seventeen new species and combinations are proposed in the generaChondrorhyncha, Cischweinfia, Cochlioda, Eloyella, Encyclia, Kefersteinia, Koellensteinia, Macroclinium, Rodriguezia, Solenidiopsis, andStenia. All new species are illustrated. A key is provided for 2-flowered species ofMacroclinium, PeruvianSigmatostalix, and PeruvianStenia. Solenidium (Solenidiopsis) peruvianum Schltr. is lectotypified.     

Lysine Dendrimers and Their Starburst Polymer Derivatives: Possible Application for DNA Compaction and in vitro Delivery of Genetic Constructs

We attempted to find some compounds for the effective delivery of gene constructs into cells and obtained two trispherical dendrimers on the basis of lysine, (Lys)₈-(,-Lys)₄-(,-Lys)₂-(,-Lys)-Ala-NH₂ (D1) and ((Lys)₈-(,-Lys)₄-(,-Lys)₂-,-Lys)-Ala-[Lys(Plm)]₂-Ala-NH₂ (D2), as well as the starburst polymeric derivatives of D1, (pVIm) ₈ -D1 and (pLys) _n -D1, containing poly(N-vinylimidazole) and polylysine chains single-point bound to the dendrimer amino groups. The conditions of dendrimer–plasmid DNA complex formation were studied. The intracellular localization of these complexes and the expression of gene constructs delivered with their help were analyzed in transfection experiments on the HeLa cell cultures of human epithelial carcinoma and on mouse C2C12 myoblasts. It was found that the chemical structure of dendrimer D1 and its derivatives significantly affected the structure and properties of complex.     

Origin and development of Tool-making behavior in Africa and Asia

Around two-and-a-half million years ago, some hominid populations in Africa began to modify stones and bones in a manner that can be recognized by prehistorians as artifacts, and, by definition, produced the earliest identifiable archaeological record. It is likely that earlier hominid groups also may have had relatively rich tool-using behavioral repertoires similar to that seen in modern chimpanzees (McGrew, 1992), such tools may have been made of perishable materials or minimally modified and thus difficult to identify. This review will focus on the earliest archaeological traces and the spread of hominids out of Africa and into Eurasia.     

Planting densities and bird and rodent absence affect size distributions of four dicots in synthetic tallgrass communities

Variability in the size distributions of populations is usually studied in monocultures or in mixed plantings of two species. Variability of size distributions of populations in more complex communities has been neglected. The effects of seeding density (35 or 350 seeds/species/m²) and presence of small vertebrates on the variability of size distributions were studied for a total of 1,920 individuals of 4 species in replicated synthetic communities of 18 species in northern Illinois. End-of season height and above-ground biomass were measured for prairie perennials Dalea purpurea (purple prairie clover), Echinacea purpurea (purple coneflower), Desmanthus illinoensis (Illinois bundleflower) and Heliopsis helianthoides (early sunflower). Variability in biomass distribution of the four target species was twice as great at low than at high densities when small vertebrates were excluded. Our results suggest that inter- and intraspecific competition may affect all individuals more under high-density conditions, thereby reducing the variability in their biomass distributions within this community. This result, a consequence of plant-plant interaction, is obscured when small birds or mammals are present, presumably because either or both add variance that overwhelms the pattern.     

Nectary structure and nectar characteristics in someBignoniaceae

The nectary structure and chemical nectar composition of 15 species belonging to 12 genera ofBignoniaceae are analyzed. All taxa bear a conspicuous nuptial nectary surrounding the ovary base. The secretory tissue is mostly supplied by phloem branches. The stomata are located in the middle and upper part of the nectary epidermis with an homogeneous distribution. The nuptial nectary is proportionally large in relation to the ovary (15–30%), disregarding the nectary volume. Most species have extranuptial nectaries in both inner and outer surfaces of the calyx. Both kinds of nectaries lack a vascular tissue that straightly supplies them. Nuptial nectar concentration (wt/wt) ranges from 19 to 68%. Sugars and amino acids are found in all species. Half of the species have hexose predominant nectars, the remaining sucrose predominant. Phenols are detected in only three species, whereas reducing acids exclusively inTecoma stans. Alkaloids and lipids were never detected. Extranuptial nectar chemical composition is analyzed in two species:Dolichandra cynanchoides andPodranea ricasoliana. Bees constitute the main flower visitors of the species studied whereas hummingbirds were seen visiting three species. A correlation analysis is performed with the data obtained. There are a few significant correlations which indicate a parallel increase of three parameters: the longer the flower length, the more voluminous the nectary and the higher stomata number, independently of the floral biotype. Phenograms are obtained using 24 floral characters including nectary and nectar data. The clusters obtained do not reflect taxonomic relationships but are useful in the understanding of animal-plant interactions when the flower biotype is considered.This paper is based on a chapter of a doctoral thesis presented at the University of Córdoba (Argentina).     

Diversity and structure of shrew communities in montane forests of southeast Kenya

As a step towards setting conservation priorities for declining moist forests in southeast Kenya, we assessed for small mammal diversity and distribution. These habitats are under severe pressure due to increased demand an forests products and arable land, yet there is a dearth of information an impacts an biodiversity. Over an eight-month period, we used a combination of box and pitfall traps with drift fences to study 13 forest fragments in five geographic areas ranging between 3°28′−4°10′ S and 38°28′−39°2b′ E. We recorded 12 species including 10 soricids and two macroscelids in 31440 trap nights. Diversity estimates using rarefaction method indicate a species richness of 12, consistent with our collection. There were six unique species, each limited in distribution to one forest fragment. Our record of Crocidura cf. selina in Kyulu Hills is the first outside Mabira forest in Uganda where it is considered endemic and endangered. We also report the first record of C. fuscomurina in Kenya, white those of C. Luna and Suncus megalura are first in the southeast of the country. By providing new ranges to four species, our study is of significance to the biogeography and conservation of forest small mammals in the region.     

Campylobacter,salmonella and chlamydia in free-living birds of Croatia

Campylobacteriosis, salmonellosis and avian chlamydiosis are zoonotic diseases in which birds have been suggested to play an important role as reservoirs. We have investigated the prevalence of Campylobacter and Salmonella spp. and Chlamydophila sp. in 107 free-living birds belonging to 25 species from 13 families from Croatia in order to examine the natural infections caused by these agents. Campylobacter jejuni-like organisms were isolated from 2 of 107 free-living bird species examined (1.9%). Salmonella was isolated from 8 fresh fecal specimens from free-living bird species (7.4%). These isolates were identified as S. typhimurium in 4 (3.7%), and S. enteriditis in 4 (3.7%) free-living birds. These samples originated from feral pigeons (Columba livia domesticus; n=14; 28.6%), rook (Corvus frugilegus; n=13; 15.4%), buzzard (Buteo buteo; n=12; 16.7%), black-headed gull (Larus ridibundus; n=8; 12.5%) and tawny owl (Strix aluco; n=8; 12.5%). The presence of Chlamydophila sp. was not detected in the free-living birds examined during this study. Epidemiological aspects and possible significance of the examined birds as a source of infections for domestic animals and humans are discussed.     

Isolation and characterization of arsenite-oxidizing bacteria from arsenic-contaminated soils in Thailand

Two hundred and eighty-eight arsenic-resistant bacteria were isolated by an enrichment culture method from a total of 69 arsenic-contaminated soil-samples collected from Dantchaeng district in Suphanburi province (47 samples), and from Ron Phiboon district in Nakhon Sri Thammarat province (22 samples), in Central and Southern Thailand, respectively. Twenty-four of the 288 isolated arsenic-resistant bacteria were found to be arsenite-oxidizing bacteria. On the basis of their morphological, cultural, physiological, biochemical and chemotaxonomic characteristics, and supported by phylogenetic analysis based upon their 16S rRNA gene sequences, they were divided into five groups, within the genera Acinetobacter, Flavobacterium, Pseudomonas, Sinorhizobium and Sphingomonas, respectively. Within genera, phylogenetic analysis using the 16S rRNA gene sequences suggested that they were comprised of at least ten species, five isolates being closely related to known bacteria (Acinetobacter calcoaceticus NCCB 22016^T, Pseudomonas plecoglossicida FPC951^T, Ps. knackmussii B13^T, Sinorhizobium morelense Lc04^T, and Sphingomonas subterranea IFO16086^T). The other five proposed species are likely to be new species closely related to Flavobacterium johnsoniae, Sinorhizobium morelense, Acinetobacter calcoaceticus and Pseudomonas plecoglossicida, but this awaits further characterization for confirmation of the taxonomic status. No overlap in isolated species or strains was observed between the two sites. The strain distribution and characterization are described.     

Amino acids and sugars in nectar,and their putative evolutionary significance

Individual amino acids and sugars from flower nectar of 32 plant species with different pollination systems were quantified and compared. Data show that there is no correlation between sugar and amino acid concentration. Furthermore there is no correlation between composition and concentration of amino acids and evolutionary advancement, nor any direct relation with pollination systems. However, higher sugar concentrations are often linked with more advanced morphological characters. Nectars from pierced or damaged flowers or nectars contaminated with pollen exhibit modifications and increases in amino acid composition. The presence of proline probably indicates such pollen contamination. Most pollinating animals depend on flower nectar in their energetic requirements, yet innumerable alternative amino acid and protein sources exist. Future research has to consider the relationship between nutritional requirements of pollinating animals and dependence on flower nectars.Dedicated to Prof. Dr.L. van der Pijl, Den Haag, in honour of his 80th birthday.     

Changes of dung beetle communities from rainforests towards agroforestry systems and annual cultures in Sulawesi (Indonesia)

Little is known about how tropical land-use systems contribute to the conservation of functionally important insect groups, including dung beetles. In a study at the margin of Lore Lindu National Park (a biodiversity hotspot in Central Sulawesi, Indonesia) dung-beetle communities were sampled in natural forest, young secondary forest, agroforestry systems (cacao plantations with shade trees) and annual cultures (maize fields), each with four replicates (n = 16 sites). At each site we used 10 pitfall traps, baited with cattle dung, along a 100 m transect for six 3-day periods. The number of trapped specimens and species richness at the natural forest sites was higher than in all land-use systems, which did not significantly differ. Each land-use system contained, on average, 75% of the species richness of the natural forest, thereby indicating their importance for conservation. However, a two-dimensional scaling plot based on NESS indices (m = 6) indicated distinct dung beetle communities for both forest types, while agroforestry systems and annual cultures exhibited a pronounced overlap. Mean body size of dung beetles was not significantly influenced by land-use intensity. Five of the six most abundant dung beetle species were recorded in all habitats, whereas the abundance of five other species was significantly related to habitat type. Mean local abundance and number of occupied sites were closely correlated, further indicating little habitat specialisation. The low dung beetle diversity (total of 18 recorded species) may be due to the absence of larger mammals in Sulawesi during historical times, even though Sulawesi is the largest island of Wallacea. In conclusion, the dung beetle fauna of the lower montane forest zone in Central Sulawesi appears to be relatively robust to man-made habitat changes and the majority of species did not exhibit strong habitat preferences.     

Identification of b,c, and d cytochromes in the membrane of Vitreoscilla

Cytochromes b, c, d, and o were identified by spectroscopic analysis of respiratory membrane fragments from Vitreoscilla sp., strain C1. Carbon monoxide difference spectra of the reduced membranes had absorption maxima at 416, 534, and 571 nm (ascribed to cytochrome o) and 632 nm (cytochrome d). Derivative spectra of the pyridine hemochromogen spectra of the membranes identified the presence of b- and c-type cytochromes in Vitreoscilla. The cyanide binding curve of the membranes was biphasic with dissociation constants of 2.14 mM and 10.7 mM which were assigned to cytochrome o and cytochrome d, respectively. Membranes bound carbon monoxide with dissociation constant 3.9 M, which was assigned to cytochrome o. Cytochrome c ₅₅₆ and a NADH-p-iodonitrotetrazolium violet reductase component were partially purified from Vitreoscilla membranes.Abbreviations INT p-iodonitrotetrazolium violet - RMF respiratory membrane fragments - K _d dissociation constant - CHAPS 3-[(3-cholamido propyl) dimethylammonio]-1-propanesulfonate - DOC sodium deoxycholate - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulfate     

Genetic and molecular analysis of a three-component transposable-element system in maize

Summary Two different factors control the mutability of an unstable allele (c2-m8810581) of the C2 gene of maize. Both an autonomous En/Spm element and an unrelated independent factor, named Mediator, are coordinately required for the excision of the insert in c2-m881058Y. According to genetic analysis, Mediator does not have the suppressor (S) function or mutator (M) function of En/Spm. Mediator has no effect on the timing or frequency of excision of Enl, En-low, or various I/dSpm elements. Hence, Mediator only mediates a specific interaction between En and the insert at c2m881058Y. Molecular analysis of c2-m881058Y has revealed a 3.3 kb, complex, En-related receptor element inserted into the second exon of the C2 gene. The ends of this element are homologous to the ends of En/Spm, but an internal l.7 kb region shows no En/Spm homology. A great degree (11–14%) of nucleotide changes, relative to Enl, occur within and between the 12 bp TNPA binding motifs. Alterations of these critical cis-determinants may account for the need for a helper factor for excision. This element is named Irma, for Inhibitor that requires Mediator also, and represents a unique, low copy number class of receptor element.     

A hypothesis on the biological role of ABH,lewis and P blood group determinant structures in glycosphingolipids and glycoproteins

A hypothesis is presented that glycosphingolipids of circulating erythrocytes are membrane-packing substances providing for an energetically cheap carbohydrate protective coat at the cell surface. The glycosphingolipids should cover the membrane surface not occupied by functional glycoproteins. This role is envisaged for the globo series of glycosphingolipids which are P^k and P antigens of human blood. Glycosphingolipids of the neolacto series terminated with non-informative A, B, H. Lewis, P₁ antigenic structures as well as with sialic acid residues should serve the same purpose. These carbohydrate structures may be also used for conferring biological inertness on otherwise functionally active carbohydrate structures and provide protection for circulatory and membrane glycoproteins from proteolysis, denaturation and recognition of potentially antigenic sites of protein moieties by the immunosurveillance system of the body. At the external body surface the same carbohydrate structures may protect cells from the action of pathogenic microorganisms and other environmental factors. The roles of the above mentioned carbohydrate sequences on glycosphingolipids and glycoproteins in the development, tumorigenesis and evolution of blood group polymorphism are discussed.Abbreviations GP glycoprotein - GSL glycosphingolipid - GC glycoconjugate     

Callus,shoot and hairy root formation in vitro as affected by the sensitivity to auxin and ethylene in tomato mutants

We analyzed the impact of ethylene and auxin disturbances on callus, shoots and Agrobacterium rhizogenes-induced hairy root formation in tomato (Solanum lycopersicum L.). The auxin low-sensitivity dgt mutation showed little hairy root initiation, whereas the ethylene low-sensitivity Nr mutation did not differ from the control Micro-Tom cultivar. Micro-Tom and dgt hairy roots containing auxin sensitivity/biosynthesis rol and aux genes formed prominent callus onto media supplemented with cytokinin. Under the same conditions, Nr hairy roots did not form callus. Double mutants combining Rg1, a mutation conferring elevated shoot formation capacity, with either dgt or Nr produced explants that formed shoots with little callus proliferation. The presence of rol + aux genes in Rg1 hairy roots prevented shoot formation. Taken together, the results suggest that although ethylene does not affect hairy root induction, as auxin does, it may be necessary for auxin-induced callus formation in tomato. Moreover, excess auxin prevents shoot formation in Rg1.     

Molecular identification of Taenia spp. in wolves (Canis lupus), brown bears (Ursus arctos) and cervids from North Europe and Alaska

Taenia tapeworms of Finnish and Swedish wolves (Canis lupus) and Finnish brown bears (Ursus arctos), and muscle cysticerci of Svalbard reindeer (Rangifer tarandus platyrhynchus), Alaskan Grant's caribou (Rangifer tarandus granti) and Alaskan moose (Alces americanus) were identified on the basis of the nucleotide sequence of a 396 bp region of the mitochondrial cytochrome c oxidase subunit 1 gene. Two species were found from wolves: Taenia hydatigena and Taenia krabbei. The cysticerci of reindeer, caribou and one moose also represented T. krabbei. Most of the cysticercal specimens from Alaskan moose, however, belonged to an unknown T. krabbei-like species, which had been reported previously from Eurasian elks (Alces alces) from Finland. Strobilate stages from two bears belonged to this species as well. The present results suggest that this novel Taenia sp. has a Holarctic distribution and uses Alces spp. as intermediate and ursids as final hosts.