Presence Of Suitable Substrate Research Articles

MOLUSCOS DE LA REGION DE LA CIENAGA GRANDE DE SANTA MARTA (COSTA DEL CARIBE DE COLOMBIA)

This paper deals with the moDusk species known from the Ciénaga Grande de Santa Marta and from the littoral zone and the upper continental shelf of the coastal strip between lala de Salamanca and the balneario El Rodadero (Caribbean coast of Colombia, South America). 468 species and subspecies ofmarine, brackish-water and freshwater mollusks are reponed comprising 211 bivalves. 6 scaphopods and 251 gastropods. 101 species and 1 subspecies have been found in the Ciénaga Grande (most of them also in the sea), a further 9 marine species have been recorded only as old shells in the estuarine part of the Ciénaga Grande, the rest have been collected exclusively in the marine part of the investigated area. 268 species (120 bivalves, 3 scaphopods and 145 gastropods) have been live-collected, the remainder only as empty shells. 165 species and 9 subspecies (90 + 1 bivalves and 75 + 2 gastropods) are monographed and discussed in detail, among them 98 species and 1 subspecies (48 bivalves and 50 + 1 gastropods) from the Ciénaga Grande or its estuarine región, and 67 species and 2 subspecies only from the sea. Of the 98 species from the Ciénaga Grande, 64 have been live-collected, tlte oth*er 34 as empty shells only. The Ciénaga Grande de Santa Marta is the largest coastal lagoon of the Caribbean coast of Colombia, occupying an area of 450 km'. According to the season, drastic changes in salinity of between 0 and S0*/oo may be observed. Depth varies between 1 and 2.5 m, and the shore mostly consists of mangrove swamps. The bottom is muddy, some more or less extended areas having oyster reefs or shell concentrates. There are small areas in the northern part with sandy bottoms. Most mollusk species enter the lagoon and spread out within it as planktonic larvae by means of the currents, if conditions are favourable. Only very rarely are adult snails able to enter {he Ciénaga Grande actively. The propagation of the planktonic larvae within the lagoon depends on the nearest natural occurrence of the species, the duration of the pelagic phase, settlement depends on the presence of suitable substrate (besides the other ecological conditions needed). On account of finding older empty shells in a relative uniform state of preservation throughout the whole basin of the Ciénaga Grande, and of species not having been encountered there live, it can be assumed that there had previously existed an extremely long period of high salinity in the lagoon, with lower amplitudes than nowadays. According to C dates this period can be located ¿00-360 years ago, and its duration is estimated at at lea»t 3.5 years. The reason for this was most probably the greater interchange of sea and lagoonal water through several no longer existing, but still traceable, inlets. The zoogeographic division of those species treated in detail (except the freshwater species) is as follows: western Atlantic species. 68; Caribbean species. 48: southern Caibbean species, partly also from Brasil, 39. Í2 species are amphi-atlantic and 5 amphi-american. Six species known from Suriname, Venezuela or Brasil are recorded for the first time from Colombia and the southwestern Caribbean. 69 species have a win species (cognate species) existing in the Eastern Pacific (Panamic zoogeographic province). The portion of species with Pacific twin species found in the studied area is very high in comparison with other regions of the Caribbean, especially among the bivalves. This is due most probably to the similarity of the biotopes on large parts of the Colombian Caribbean coast and the tropical Eastern Pacific coast, preferred by these species.

Influence of Time since Fire and Micro-Habitat Availability on Terricolous Lichen Communities in Black Spruce (Picea mariana) Boreal Forests

Terricolous lichens are an important component of boreal forest ecosystems, both in terms of function and diversity. In this study, we examined the relative contribution of microhabitat characteristics and time elapsed since the last fire in shaping terricolous lichen assemblages in boreal forests that are frequently affected by severe stand-replacing fires. We sampled 12 stands distributed across five age classes (from 43 to >200 years). In each stand, species cover (%) of all terricolous lichen species and species richness were evaluated within 30 microplots of 1 m2. Our results show that time elapsed since the last fire was the factor that contributed the most to explaining terricolous lichen abundance and species composition, and that lichen cover showed a quadratic relationship with stand age. Habitat variables such as soil characteristics were also important in explaining lichen richness. These results suggest that the presence of suitable substrates is not sufficient for the conservation of late-successional terricolous lichen communities in this ecosystem, and that they also need relatively long periods of times for species dispersal and establishment.

Analysis of Factors Affecting Zebra Mussel ( Dreissena polymorpha) Growth in Saginaw Bay: A GIS-Based Modeling Approach

A statistical model was developed using a Geographical Information System (GIS) to investigate the spatial relationships between limnological variables and the growth of zebra mussels ( Dreissena polymorpha) in Saginaw Bay, Lake Huron, as defined by the change in biomass over a specified time. The presence of suitable substrate was an important factor for zebra mussel habitat, making inner Saginaw Bay an area of high mussel abundance. Temperature, phytoplankton biomass (measured as chlorophyll a), and total suspended solids (TSS) as food particles were considered to be the most important limnological variables affecting growth of zebra mussels. Three layers of attributes were developed from these variables, and were overlaid in a GIS environment according to their respective weighting factors, which were calculated in statistical analysis of spatially-matched data. The model results showed that chlorophyll a contributed the most to mussels’ growth. The effect of chlorophyll a on Dreissena growth was 9 times more important than that of temperature. The shallow portions of the inner bay and the areas in proximity to the shorelines were found to be the most suitable growth regions. A comparison of model predictions with field data on growth of mussels at various spatial locations of the inner bay demonstrated the value of this model. In addition, the model was field-tested for temporal variation in the rate of change of Dreissena biomass at one sampling station where data were available. The developed GIS-based statistical model provides a rapid, objective, reliable and cost effective tool to prioritize locations of Dreissena growth.

The hydrodynamic and sedimentary setting of nearshore coral reefs, central Great Barrier Reef shelf, Australia: Paluma Shoals, a case study

The Great Barrier Reef (GBR) shelf contains a range of coral reefs on the highly turbid shallow inner shelf, where interaction occurs with terrigenous sediments. The modern hydrodynamic and sedimentation regimes at Paluma Shoals, a shore‐attached ‘turbid‐zone’ coral reef, and at Phillips Reef, a fringing reef located 20 km offshore, have been studied to document the mechanisms controlling turbidity. At each reef, waves, currents and near‐bed turbidity were measured for a period of ≈1 month. Bed sediments were sampled at 135 sites. On the inner shelf, muddy sands are widespread, with admixed terrigenous and carbonate gravel components close to the reefs and islands, except on their relatively sheltered SW side, where sandy silty clays occur. At Paluma Shoals, the coral assemblage is characteristic of inner‐shelf or sheltered habitats on the GBR shelf (dominated by Galaxea fascicularis, up to >50% coral cover) and is broadly similar to that at Phillips Reef, further offshore and in deeper water. The sediments of the Paluma Shoals reef flats consist of mixed terrigenous and calcareous gravels and sands, with intermixed silts and clays, whereas the reef slope is dominated by gravelly quartz sands. The main turbidity‐generating process is wave‐driven resuspension, and turbidity ranges up to 175 nephelometric turbidity units (NTU). In contrast, at Phillips Reef, turbidity is <15 NTU and varies little. At Paluma Shoals, turbidity of >40 NTU probably occurs for a total of >40 days each year, and relatively little time is spent at intermediate turbidities (15–50 NTU). The extended time spent at either low or high turbidities is consistent with the biological response of some species of corals to adopt two alternative mechanisms of functioning (autotrophy and heterotrophy) in response to different levels of turbidity. Sedimentation rates over periods of hours may reach the equivalent of 10 000 times the mean global background terrigenous flux (BTF) of sediment to the sea floor, i.e. 10 000 BTF, over three orders of magnitude greater than the Holocene average for Halifax Bay of <3 BTF. As elsewhere along the nearshore zone of the central GBR, dry‐season hydrodynamic conditions form a primary control upon turbidity and the distribution of bed sediments. The location of modern nearshore coral reefs is controlled by the presence of suitable substrates, which in Halifax Bay are Pleistocene and early Holocene coarse‐grained (and relatively stable) alluvial deposits.

Role of Quinone Reductase in in Vivo Ethanol Metabolism and Toxicity

Quinone reductase (QR), in the presence of suitable substrate. results in the regeneration of NAD + from NADH. To test the hypothesis that QR can play a role in ethanol metabolism and toxicity, we studied the effect of a quinone as well as of induced levels of QR on ethanol administered in vivo to male rats and mice. Butylated hydroxyanisole (BHA) is known both to induce QR and to be metabolized to tert-butyl quinone (TBQ). Dietary BHA (0.75% for 10 days), followed by oral ethanol (4 g/ kg, by gavage), increased the rate of ethanol disappearance and decreased the area under the curve (AUC) for blood ethanol in both rats and mice. In addition, BHA pretreatment of rats was shown to prevent ethanol-induced 24-hr hepatic triglyceride accumulation. Also, in rats, TBQ (5 mg/kg, ip) led to decreased AUC and hepatic triglyceride accumulation, although the ethanol disappearance rate was not significantly affected. TBQ in BHA-fed rats resulted in even greater effects on the ethanol disappearance rate and AUC than TBQ or BHA treatment alone. None of these treatment regimens resulted in a significant change in volume of distribution of ethanol. Thus, these results support the hypothesis that induction of QR and/or administration of quinones leads to enhanced in vivo metabolism of ethanol and decreased hepatotoxicity.

Luminescence-based fibre-optic probes

New fibre-optic probes with both high selectivity and sensitivity have been designed in our group, based on light-emitting reactions (LER). Chemiluminescence reactions involving luminol and requiring hydrogen peroxide are particularly interesting, as they can be enzymatically catalysed by peroxidase, as well as bioluminescence reactions catalysed by luciferases either from the firefly or from marine bacteria, which provide a light emission correlated to the concentration of ATP or NAD(P)H, respectively. Co-immobilization of other enzymes like dehydrogenases used as auxuliary enzymes enabled the performance of the probe to be extended to other target molecules. In parallel, in the presence of suitable substrates, dehydrogenases activities can be monitored using the bacterial bienzyme system. The design of a reagentless probe has been investigated using the combination, in a multifunction sensing layer, of covalent immobilization technique for enzymes associated with loose embedding for co-reactants. Flavin mononucleotide can be trapped in a polyvinyl alcohol matrix, allowing about 35–40 consecutive accurate measurements to be performed. Promising results have also been obtained by connecting such probes to flow-injection-analysis manifolds for the monitoring of biotechnological processes. The potential of chemiluminescence and bioluminescence is especially attractive, since no light source or monochromator is required and since their sensitivity, selectivity and polyvalence appear particularly promising for extended development.

(Bromomethyl) lithium: Efficient in situ Reactions

(Bromomethyl)lithium has been generated by the addition of butyllithium to dibromomethane in the presence of suitable substrates in tetrahydrofuran at -78 °C. Aldehydes or ketones yielded oxiranes (85-93%), triisopropyl borate yielded diisopropyl (bromomethyl)boronate (89%), and boronic esters without functional substituents underwent methylene insertion into the carbon-boron bond (95-97%).

The metazoan fauna of a sewage‐carrying wadi, Nahal Soreq (Judean Hills, Israel)

Summary(1) An analysis of the metazoan fauna of Nahal Soreq was made at several sampling stations from October 1970 to August 1971. Relative abundance of each species or group of species was estimated by semi‐quantitative sampling, and population structures are given here in the form of percentage tables. (2) A succession of three zones, indicating three degrees of pollution, were recognized: a ‘Nematode zone’ in the most polluted waters, a ‘Chironomus zone’, where purification has progressed a little, and a ‘Proasellus (and ostracod) zone’, where purification is nearing completion. (3) These zones of indicator organisms roughly correspond to three zones classified in a ‘Saprobien System’ manner: a polysaprobic zone (Nematode zone), a mesosaprobic zone (Chironomus zone), and an oligosaprobic zone (Proasellus zone). A state of complete purification or recovery is not reached, and the purification process is stopped in the oligosaprobic condition by the disappearance of the stream underground. The other invertebrates characterizing these three zones are given. (4) A comparison is made of the saprobic zones and their corresponding fauna with findings reported elsewhere‐‐‐Europe, North America and South Africa. The successional changes are generally similar to European findings with some notable absentees, and there are also some similarities with polluted South African streams. (5) Seasonal changes in species composition and the position of these species along the stream are discussed. There are small changes which appear to be a result of life cycle habits in some air‐breathing dipterans and a slight change in the position of chironomids downstream, which is correlated with the winter rain floods. (6) The faunal types and numbers occurring downstream are compared with the increase in algal species diversity, dissolved oxygen and coli bacterial counts. It is suggested that the degree of pollution is the primary factor in the establishment and population build‐up of any particular species, but that presence of suitable substrates, availability of food and presence of predators play a larger part where the water is cleaner.

Preparative electrochemistry of Ph3AsOHClO4, (Ph3AsO)2 HClO4, Ph3AsOHCl and Ph3AsOBF3 by anodic oxidation of triphenylarsine

Abstract The electrochemical oxidation of triphenylarsine in wet acetonitrile at platinum electrodes is suggested as a procedure for preparing some triphenyl-arsine oxide derivatives and the anodic behaviour of Ph 3 As in presence of suitable substrates (perchlorates, chlorides and tetrafluoborates) is described. Hydroxytriphenylarsonium chloride is formed in a chemical reaction involving triphenylarsine and chlorine radicals produced anodically while in the other cases Ph 3 As is directly oxidized at the platinum surface. In all processes an hydrolysis reaction due to the wetness of the solvent is also involved. To account for Ph 3 AsOBF 3 formation, elimination of hydrogen fluoride from hydroxytriphenylarsonium tetrafluoborate is suggested. (Ph 3 AsO) 2 HClO 4 is obtained by a partial reduction of Ph 3 AsOHClO 4 formed in the anodic process involving Ph 3 As when perchlorates are used as supporting electrolytes.

One Hundred Years of Suez Canal-A Century of Lessepsian Migration: Retrospect and Viewpoints

Por, F. D. (Dept. of Zoology, Hebrew Univ., Jerusalem) 1971. One hundred years of Suez Canal–a century of Lessepsian migration: Retrospect and Viewpoints. Syst. Zool., 20:138–159. One hundred years has passed since one of the biggest biogeographical experiments started with the opening of the Suez Canal. The successful migration along the Canal of a great many Red Sea species into the Mediterranean is seen as a process to which most of these species were preadapted in the littoral environment of the Red Sea. The repeated transgressions of this sea into the basin of the Bitter Lakes and the existence—presently and in the past—of several slightly hypersaline lagoons along its shores, resulted in the creation of a special stock of species able to perform this migration. Progress through the Canal is either a step-by-step one, or a result of active swimming (or transport). Neither the role of planktonic spread by means of larvae and/or currents, nor the obstacles put by the salinity, should be overemphasized. The main factors in helping or hindering migration are considered to be the presence of suitable substrates and water transparencies in the Canal. The Levant Basin of the Mediterranean was also “preadapted” to receive the immigrants because of its high salinity and temperature and the resulting biological undersaturation with temperate fauna. Most probably this explains the one-way stream of the migrants into the Mediterranean. The distribution limits of the immigrants in the Mediterranean are most probably set by the increasing competitive capacities of the aboriginal species. The westward advance of the immigrants in the Mediterranean will probably become more pronounced after the damming of the Nile waters behind the newly erected Ass wan dam.

Carbon dioxide fixation in malaria (Plasmodium iophurae).

THE main function of the mature erythrocyte is the transport of oxygen to and the removal of carbon dioxide from the tissues. The obligate intraerythrocytic parasite, malaria, not only requires constituents of the red blood cell such as haemoglobin and glucose, but also the gases transported by its host cell. The role of oxygen in the metabolism of the malaria parasite is well documented, and stems from the early observation that in vitro blood infected with malaria soon loses its bright red appearance and darkens1. Aerating the cells restores the brightness, and the parasites continue to maintain themselves by utilizing the oxyhaemoglobin for aerobic metabolism. In spite of the fact that infected erythrocytes and even erythrocyte free malaria parasites consume oxygen in the presence of suitable substrates, only 25–50 per cent of the available glucose is aerobically degraded to carbon dioxide and water2. Thus, malaria parasites are principally facultative aerobes and the best gas mixture for maintaining parasitized erythrocytes in vitro is 95 per cent air + 5 per cent carbon dioxide3. By contrast, the role of carbon dioxide in the metabolism of malaria is not well understood and is restricted to a single, equivocal record some 20 years ago4. The present communication presents unequivocal evidence for a functional role of carbon dioxide in the metabolism of malaria parasites and erythrocytes infected with malaria.

Sterilization of Soil by Irradiation and Some Further Observations on Soil Enzyme Activity

AbstractAs an introduction to the study of radiation‐sterilized soil as a medium for microbial and plant growth, survival curves for microorganisms have been obtained with 5 and 9 Mev. electrons, hard X‐ray and gamma radiation. For a given soil, bacterial survival curves with these radiations are almost superimposable, but they differ among soils. Bacterial numbers in soils approach zero at 2 Mrep. doses, but 4 Mrep. doses are necessary to insure complete sterility for larger soil volumes.Soil sterilized by radiation still manifests enzyme activity (phosphatase, urease) in the presence of suitable substrates. If this is a general situation, studies of the uptake of some organic nutrients from sterile soil by sterile root systems will not be free from the problem of hydrolysis in situ. Sterilized soil is not toxic toward tomato plants nor does it provide extra nutrient to the plants as a result of radiation. It does, therefore, provide the plant physiologist with a medium for the study of uptake of inorganic nutrients by sterile plants which possesses all the purely chemical and structural features of natural soil.

The Reduction and Oxidation of Glutathione by Plant Mitochondria

is catalyzed by glutathione reductase (3, 4, 5). In earlier studies this reaction has been coupled with soluble dehydrogenases which utilize TPN as a coenzyme (6). Since tissue fractionation studies have shown that numerous dehydrogenases, including those associated with the oxidation of the Krebs cycle intermediates, are localized within the mitochondrion, it was of interest to determine whether these enzymes might also be coupled with reaction 1. This paper reports that it is possible to demonstrate the reduction of GSSG by plant mitochondria in the presence of suitable substrates. In addition, the plant particles also catalyzed the oxidation of GSH by molecular 02 in the presence of catalytic amounts of ascorbic acid.