Starch Metabolism in Shoot-forming Tobacco Callus

Starch, free sugars and protein contents, and the specific activitiesof enzymes of starch metabolism were determined in tobacco calluscultured under shoot-forming and non-shoot-forming conditions.Shoot-forming cultures contained higher levels of starch, freesugars and protein. Shoot-forming cultures had higher specificactivities for starch-synthesising enzymes throughout culture.On the other hand, higher levels of activity for starch-degradingenzymes in shoot-forming tissues were only observed during organizeddevelopment. The role of phosphorylase in the cultured tissuewas not clear.     

Phylogenetic relationships and molecular evolution in uropeltid snakes (Serpentes: Uropeltidae): allozymes and albumin immunology

Multilocus electrophoretic methods and microcomplement fixation comparisons of serum albumin are used to assess phylogenetic relationships among species of uropeltid snakes, to infer aspects of their population biology and biogeography, and to evaluate their relationships to other primitive snakes (Henophidia). There is very good agreement between phylogenetic inferences derived from the electrophoretic data and those derived from the albumin immunological data. Protein variation detected by electrophoresis is relatively high among 17 operational taxonomic units (OTUs) examined. The mean number of alleles per locus (5.1 across all OTUs), levels of polymorphism (25% of loci), and heterozygosity (4–6%), are typical of, or greater than, values reported for other snakes. Species of uropeltids are genetically highly differentiated, as measured by genetic distances (lowest interspecific Nei's unbiased genetic distances, 0.22-0.27 among several Sri Lankan species; 2.3 between Teretrurus of India and other uropeltines). The phylogenetic tree most consistent with both the immunological and electrophoretic data shows uropeltines from Sri Lanka to be monophyletic, but the Indian species are paraphyletic with respect to those from Sri Lanka. Rhinophis travancoricus of India is inferred to be the sister taxon to the Sri Lankan radiation. As the genera are presently understood, neither Rhinophis nor Uropeltis appears to be monophyletic. A biogeographic scenario derived from the phylogenetic hypothesis suggests an early diversification of uropeltids in India, followed by a single invasion into the lowlands of Sri Lanka. Subsequent evolution on Sri Lanka resulted in occupation of montane biotopes. Cylindrophis is the sister group to uropeltines and is considered a member of the Uropeltidae. The immunological data indicate no phylogenetic association between uropeltids and other ‘anilioid’ taxa, specifically Anilius, Loxocemus or Xenopeltis, although we cannot rule out a very remote relationship. We specifically reject the hypothesis that uropeltines and scolecophidians form a clade relative to henophidians. High levels of genetic variation and a trend toward negative F_IS values for polymorphic loci in three populations suggest generally large effective population sizes and outbreeding in these species. The niche-width variation hypothesis for allozyme loci is not supported by the uropeltid data. In comparison to other vertebrates, the relationship between Nei's genetic distance and albumin immunological distance in uropeltids suggests either conservative albumin evolution or strong differentiation at electrophoretic loci.     

Coccidian Parasites (Apicomplexa: Eimeriidae) from Insectivores. VI. Six New Species from the Eastern Mole,Scalopus aquaticus1

ABSTRACT Thirteen eastern moles, Scalopus aquaticus, collected in West Texas were examined for coccidian oocysts; 11 (85%) were infected and eight (73%) of these had multiple infections representing two or more species. One cyclosporan, three eimerians, and two isosporans were studied and all are described as new species. Sporulated oocysts of Cyclospora megacephali n. sp. were subspheroidal, 18.5 × 15.7 (14–21 × 12–18) μm; they had sporocysts pointed at one end with Stieda bodies nearly as wide as the sporocysts themselves, and were 15.0 × 7.2 (11–17 × 6–9) μm; C. megacephali was found in four (31%) hosts. Sporulated oocysts of Eimeria scalopi n. sp. were spheroidal to subspheroidal, 13.6 × 12.6 (11–17 × 11–15) μm with sporocysts lemon-shaped, 8.7 × 5.5 (7–10 × 4–7) μm; it was found in six (46%) hosts. Sporulated oocysts of Eimeria aquatici n. sp. were asymmetrically ellipsoidal, 17.0 × 10.6 (14–20 × 9–14) μm, with sporocysts elongately ovoidal, 9.0 × 5.2 (8–11 × 4–6) μm; it was found in two (15%) hosts. Sporulated oocysts of Eimeria motleiensis n. sp. were subspheroidal, 17.0 × 15.3 (15–20 × 13–18) μm with sporocysts ovoidal, 10.7 × 6.8 (10–13 × 6–8) μm; it was found in seven (54%) hosts. Sporulated oocysts of Isospora motleiensis n. sp. were spheroidal to subspheroidal, 13.6 × 12.0 (10–17 × 8–15) μm with sporocysts broadly ovoidal, 9.5 × 6.7 (7–11 × 4–8) μm; it was found in nine (69%) hosts. Sporulated oocysts of Isospora aquatici n. sp. were subspheroidal, 20.9 × 18.4 (15–24 × 13–21) μm with sporocysts ellipsoidal, 11.8 × 9.0 (9–14 × 7–11) μm; it was found in two (15%) hosts.     

How Does the Plant Plasma Membrane H+-ATPase Pump Protons?

The plasma membrane H⁺-ATPase couples ATP hydrolysis to protontransport thereby establishing the driving force for solutetransport into and out of plant cells. As such, this enzymeparticipates in a number of cellular processes important tothe overall physiology of plants. From biochemical studies andthe recent application of molecular approaches, the enzyme reactionmechanism and structure of this protein have been characterized.However, our basic understanding of how this enzyme links theendergonic reaction of ATP hydrolysis to proton translocationis far from complete. In this review, several significant questionsregarding the energy coupling mechanism will be addressed interms of information available on the plant plasma membraneH⁺-ATPase and from studies on other P-type transport ATPases.These questions focus on the chemical nature of proton translocation,how this is linked or driven by the ATP hydrolysis reactionand what role, if any, K⁺ has in the transport process. Key words: Energy coupling, membranes, bioenergetics, ion transport, P-type transport ATPase     

The influence of copper exposure on predator-prey interactions in aquatic insect communities

SUMMARY. 1. Vulnerability of two species of net-spinning caddisflies (Chimarra sp. and Hydropsyche morosa) to predation by the stonefly, Paragnetina media , was significantly greater in experimental streams dosed with copper (target concentration=6 μg 1^-1) than in control streams.
2. Results of stomach analyses showed that Hydropsychidae was the major component of stonefly diets in experimental streams and that the number of Hydropsychidae per stonefly gut was significantly greater in dosed streams than controls.
3. Since these results could not be predicted using single species bioassays, we suggest that such simple tests be supplemented with more environmentally realistic procedures that account for species interactions.     

Plasmodium (Huffia) hermani sp. n. from wild turkeys (Meleagris gallopavo) in Florida*

SYNOPSIS. Plasmodium (Huffia) hermani sp. n. is described from wild turkeys (Meleagris gallopavo Linnaeus) in Florida. It produces rounded schizonts with 6–14 nuclei arranged peripherally as a rosette and elongate, slender gametocytes with irregular margins. Asexual stages parasitize all cells in the erythrocyte series and, in heavy infections, predominantly occur in erythroblasts and their precursors. Presence and degree of pigmentation vary with maturity of the host cell. Gametocytes occupy erythrocytes only, with pigment dispersed in black granules throughout the cytoplasm. Cells containing schizonts are often rounded and enlarged and those parasitized by gametocytes may be somewhat distorted in shape by lateral hypertrophy. Host cell nuclei may be displaced, but are not distorted, except slightly by pressure from the parasite. Plasmodium hermani differs from P. (Giovannolaia) durae by producing low level (> 6%), nonlethal parasitemias in turkey poults, an absence of phanerozoites in capillary endothelium of the brain and viscera, and inability to infect chicks. Plasmodium hermani is more like P. (Huffia) elongatum in gametocyte morphology, schizogony in all types of erythrocyte precursors, with gametocytes occurring in erythrocytes only, and concentration of schizonts in heavy infections in bone marrow and spleen. It differs from P. elongatum by its lack of infectivity to passeriform and anseriform hosts and by a strong immune response which develops in infected birds.     

Comparative studies of Trypanosoma vespertilionis Battaglia and Trypanosoma dionisii Bettencourt & França

SYNOPSIS. In diphasic blood agar media Trypanosoma vespertilionis developed spheroid clusters as compared to rather long, sausage-shaped (sometimes branched) clusters formed by Trypanosoma dionisii. The former species attained a greater population density (∼6 × 10⁷ organisms/ml) than the latter (∼ 2 × 10⁷ organisms/ml). Greater numbers of epimastigotes, some in active binary divisions, were observed during the logarithmic phase of growth, and morphologic changes occurred during cultivation which correlated with increased acidity and a depletion of glucose. Maximum numbers of trypomastigote forms were found during the stationary and early death phases. Most of the forms observed after 20 days were sphaeromastigotes. Glucose concentrations decreased to 0 M in T. vespertilionis and to 4.4 × 10⁻⁵ M in T. dionisii cultures during the stationary and death phases. By the 12th day of incubation cultures of T. vespertilionis were more acid (pH 5.5) than those of T. dionisii (pH 6.5). No antigenic changes during cultivation of each of the parasites were detected by immunodiffusion. Trypanosoma vespertilionis and T. dionisii contained common and specific antigens. At least 2–3 common antigens were detected in extracts reacted against heterologous antisera. Specific antigens were observed as nonidentical lines formed by extracts reacted against homologous and heterologous antisera and with antisera absorbed with heterologous antigens. At least 2 specific antigens were evident in extracts of T. vespertilionis and 1 in extracts of T. dionisii.     

THE USE OF MOLLUSCAN SHELL GROWTH PATTERNS IN ECOLOGY AND PALEOECOLOGY

The influence of substratum, depth of water, turbidity, and temperature on daily growth patterns has been studied by transplanting juvenile Mercenaria mercenaria (Linnaeus) from the laboratory to intertidal and subtidal environments.
The study of seasonal growth variations in a population of Gemma gemma Totten from Long Island Sound shows that shell growth patterns may be used to determine the season of death and age of dead shells.
Deep-water species (e.g. Nucula cancellata Jeffreys, Malletia sp., and Calyptogena ponderosa Boss) exhibit growth increments that are more uniform in thickness and less sharply defined than those in shallow-water species.