Population dynamics of annual Salicornia species in the tidal salt marshes of the Oosterschelde,The Netherlands

1. The population dynamics of two Salicornia species from the Bergen op Zoom salt marsh (south-west Netherlands) was examined. Based on the results of several field studies three preliminary life tables were constructed, two for S. procumbens agg. populations growing respectively on the mud flats and in the salt marsh, and one for S. europaea agg. living in the upper marsh.
2. The life cycles are described and quantified in terms of eight phases and the transition probabilities between them, starting from a notional individual representative of each population.
3. The models depicting the life cycle of S. procumbens show a mean offspring number of 4.26 individuals per parent for the mud-flat population and 0.18 for the salt-marsh population. The S. europaea model gives an output of 0.44 individuals per parent. These results reflect the fluctuations in population size observed in sample plots over the years 1976–78.
4. Comparison of the transition probabilities reveals that on the mud flats most S. procumbens individuals die during pollination and seed germination, while the population in the salt marsh proper is thinned especially during the seed phase in winter time and during the growth from established seedlings to maturation. S. europaea behaves in a similar but less pronounced way to S. procumbens in the salt marsh.
5. Probabilities for one flower or one seed to produce a mature flowering plant were calculated, and were compared with those found in the literature. They are roughly of the same order of magnitude as the probabilities for other annual species, but much higher than those reported for biennial species.

     

Growth of a floating aquatic weed,Salvinia under standard conditions

1. Growth of the floating aquatic weed, Salvinia, in sterile culture was exponential for at least 2 weeks under standardized conditions.
2. Increase in light intensity or in CO₂ resulted in increases in growth rate, but did not extend the exponential period of growth.
3. This aquatic plant, like many others, discriminates against calcium relative to strontium.
4. In culture Salvinia exhibited luxury consumption of N and P.
5. Because of high C/N ratios, Salvinia may not be a favorable source of animal food, but might be useful in nutrient removal schemes.
6. In sterile culture, S. molesta produced fewer leaves than S. minima, but maintained a significant increase in leaf area and dry weight. This may be correlated with the ability of the first species to rapidly spread over tropical waterways.

     

Survival,osmoregulatory ability,and respiration of idotea chelipes (Crustacea,Isopoda) from lake veere in different salinities and temperatures

1. An ecological and physiological study ofI. chelipes from Lake Veere, The Netherlands, was made.
2. Both osmoregulatory capacity and survival decrease with increasing temperature as well as with decreasing salinity.
3. Respiration experiments suggest that the need of energy by osmoregulatory activity may be supplied at the cost of other physiological processes, at any rate at temperatures of 10°C and higher.
4. It may be expected that, if temperatures higher than 15°C and salinities lower than 8‰ coincide, the population ofI. chelipes will be affected negatively.

     

Chlorophenol and chlorobenzoic acid co-metabolism by different genera of soil bacteria

1. FourPseudomonas strains, anAchromobacter sp., threeNocardia strains,Mycobacterium coeliacum and aBacillus sp., grown on either phenol or benzoic acid as sole carbon source, were tested for co-oxidation of monochlorophenols and monochlorobenzoates respectively.
2. ThePseudomonas spp.,Nocardia spp.,M. coeliacum and theBacillus sp. showed O₂-uptakes in the presence ofo-, m- orp-chlorophenol and oxidised them to either 3- or 4-chlorocatechol.
3. Benzoate-grown cells of the threeNocardia spp. and three of the pseudomonads absorbed O₂ only in the presence ofm-chlorobenzoate, 4-chlorocatechol being identified as the oxidation product in two cases. One pseudomonad gave some O₂-uptake also in presence ofp-chlorobenzoate.
4. Benzoate-grownBacillus cells gave O₂-uptakes with eitherm- orp-chlorobenzoate and the former was oxidised to 5-chloro-2,3-dihydroxybenzoic acid via 5-chlorosalicylic acid, thus representing a novel metabolic pathway.

     

Particularites de l'infestation adiaspiromycosique par Emmonsia crescens Emmons et Jellison, 1960 chez Pitymys subterraneus (De Selys-Longchamps 1836) et Mustela nivalis nivalis L. 1766

From the observation of some hundred lungs of small wild mammals in France, we have found two types of parasitism byEmmonsia crescens Emmons &Jellison, (1960). In most species, for example inApodemus sylvaticus andClethrionomys glareolus, the adiaspores ranged from 200 to 475 µ in diameter, their cell walls are 28 µ in average thickness and they cause a weak histological reaction in the parenchyma of the lungs. InPitymys subterraneus, the adiaspores are always much smaller, about 85 µ. They have a thin cell wall, 4 µ, and are surrounded by a strong histological reaction, the thickness of which ranges from 130 to 140 µ. The adiaspores observed inMustela nivalis nivalis are still smaller, about 70 µ, and they provoke a pulmonary reaction a hundred µ thick. However, we think that these small adiaspores belong to the speciesEmmonsia crescens Emmons &Jellison, (1960):

1. they germinate springing many mycelian tubes.
2. the macroscopic and microscopic morphological characteristics of the mycelian phase are identical to those of several strains ofEmmonsia crescens.
3. the mycelian phase completely turns into the yeast phase at 37° C on “Brain Heart Agar” Difco.
4. a strain isolated from aP. subterraneus, inoculated to a white mice, a bank vole or a field vole gives big adiaspores typical ofE. crescens in their respective lungs.
5. from an epidemiologic point of view, it is difficult to imagine such a narrow cohabitation of two species of so non specific germ having each its own host.

     

Different promoter regions control level and tissue specificity of expression of Agrobacterium rhizogenes rolB gene in plants

Expression of the rolB gene of A. rhizogenes T-DNA triggers root differentiation in transformed plant cells. In order to study the regulation of this morphogenetic gene, the GUS reporter gene was placed under the control of several deleted fragments of the rolB 5 non-coding region: carrot disc transformations and the analysis of transgenic tobacco plants containing these constructions identified the presence of distinct regulatory domains in the rolB promoter. Two regions (located from positions –623 to –471 and from –471 to –341, from the translation start codon) control the level but not the tissue specificity of rolB expression: progressive deletions of the rolB promoter starting from position –1185 to –341, although at different levels, maintained the same pattern of GUS expression — maximal in root meristems and less pronounced in the vascular tissue of aerial organs. Further deletion of 35 bp, from –341 to –306, drastically affected tissue specificity: GUS activity was still clearly detectable in the vascular tissue of the aerial organs while expression in the root meristem was totally suppressed. Analysis of transgenic embryos and seedlings confirmed that distinct promoter domains are responsible for meristematic (root) and differentiated (vascular) expression of rolB. Finally, we present data concerning the effects of plant hormones on the expression of rolB-GUS constructions.     

Ecology of deepwater rice-fields in Bangladesh 4. Nitrogen fixation by blue-green algal communities

1. Aquatic macrophytes formed dense beds in fallow areas during the four and a half months of the flood season in all but one deepwater rice-growing location in Bangladesh; these included several types of life-form, but the fine-leaved species, Myriophyllum sp., Najas indica, Utricularia stellaris were often especially abundant. The same species grew inside deepwater rice fields, but at much lower densities. A similar contrast occurred for the algae, although deepwater rice often developed dense masses of epiphytes on aquatic roots, stems and leaf sheaths, when plants were growing in isolated, well-illuminated situations.
2. Two widespread algae, Aulosira fertilissima and Scytonema mirabile, were equally successful on soil in the period prior to the arrival of floodwaters and floating on the surface of the water during the flood season. Other species common during the flood season differed from those common on soil.
3. Most blue-green algae inside deepwater rice fields were heterocystous; the only species not so, but forming distinct colonies, was Aphanothece stagnina. However only non-heterocystous forms were found at one location in south Bangladesh (Phaltita) and a change from heterocystous to non-heterocystous forms was noted at the main research site (near Sonargaon) during late September in at least one year. The water column at the former was almost entirely anoxic, while the change at the latter occurred at a time when the water sometimes became anoxic during the night. It is suggested that differences in ability to tolerate anoxic periods may be a key factor in determining the success of the algal and vascular plant species in the different micro-habitats within these DWR-growing areas.
4. Although diatoms were quantitatively only a minor component of the algal biomass, they became more frequent later in the season when the water became microaerobic or anoxic for part of the day. Navicula confervacea was overall the most abundant species at the two main research locations.

     

Das Vorkommen von Malatenzym und Malo-Lactat-Enzym bei verschiedenen Milchsäurebakterien

1. Malic enzyme was induced by malic acid and malo-lactic enzyme was induced by malic acid and glucose in cells of three strains ofLactobacillus casei that were able to grow on malate as carbon source. Two strains ofStreptococcus faecalis formed malic enzyme only, whereas only malo-lactic enzyme was formed by a glucose requiring strain ofStreptococcus lactis.
2. Given sequential induction, cells ofLactobacillus casei M40 were found to contain malic enzyme and malo-lactic enzyme simultaneously.
3. Malic enzyme and malo-lactic enzyme have been separated by chromatography on Sephadex G-200. These two enzymes have a different pH optimum, different affinities for substrates, form different end products from malate, and have molecular weights of 120000 and 150000 daltons respectively.

     

Flocculation phenomenon of Candida albicans by lysozyme

Young colonies of Sabouraud's glucose agar room temperature culture ofCandida species from human isolation were suspended in distilled water. The suspension was mixed with a solution of lysozyme and incubated in a 37° C water bath. Within 3–5 hours, various species ofCandida cells showed flocculation to varying degrees which occurred at varying periods of onset. Among sevenCandida species,Candida albicans andCandida stellatoidea showed the strongest flocculation, earliest onset and most solution clarity than did any other species.Candida stellatoidea was indistinguishable fromCandida albicans in its degree of flocculation, and in the clarity of solution.Candida species may be arranged in the following order according to their decreasing positivity in flocculation:

1. Candida albicans
2. Candida stellatoidea
3. Candida tropicalis
4. Candida krusei
5. Candida pseudotropicalis
6. Candida parapsilosis
7. Candida guilliermondii
8. Saccharomyces species may be placed afterCandida guilliermondii.

It seems possible to separate theCandida species into 3 groups by the rate of flocculation, and clarity of solution. Group I.Candida albicans andCandida stellatoidea. Group II.Candida tropicalis, C. krusei andCandida pseudotropicalis. Group III.Candida parapsilosis andCandida guilliermondii. Saccharomyces specimens (S. cerevisiae and others) were placed after group III.     

Cocaine kindling in mice

Previous studies proposed the involvement of theN-methyl-D-aspartate (NMDA) type of glutamate receptors in the development of sensitization to the convulsive effect of cocaine (cocaine kindling). The present study was undertaken to determine, first, if cocaine kindling is associated with enhanced sensitivity of the NMDA receptor to the convulsive response ofN-methyl-D,L-aspartate (NMDLA), and second, whether in vivo modulation of nitric oxide synthase (NOS) function regulates the development of cocaine kindling. The following results were observed:

1. Cocaine-kindled animals were significantly more susceptible to the convulsive effect of the NMDA receptor agonist NMDLA than saline controls;
2. Pretreatment with the NOS inhibitor N^G-nitro-L-arginine methyl ester (L-NAME; 100 mg/kg; ip) blocked the development of cocaine kindling;
3. The protective effect of L-NAME was partially reversed with the coadministration of the NOS substrate,L-arginine (300 mg/kg; ip), but notD-arginine; and
4. L-Arginine (300 mg/kg; ip), but notD-arginine, amplified the development of cocaine kindling. Taken together, these findings suggest that supersensitivity of the NMDA receptor and activation of NOS may underlie the development of cocaine kindling.

     

Encoding of plant odours by receptor neurons in the pine weevil (Hylobius abietis) studied by linked gas chromatography-electrophysiology

Receptor neuron responses to plant volatiles, trapped by head-space procedures, were examined in the pine weevil Hylobius abietis, using gas chromatography linked with electrophysiological recordings from single neurons. Seventy-two receptor neurons were tested 173 times for various plant volatile mixtures, either via a polar or a non-polar column.

1. All responses appeared as increased firing rates which followed the concentration profiles of the GC-eluted compounds.
2. The neurons were classified separately for the two column types in 17 and 19 groups respectively, according to the compounds they responded to. It suggests that the plant odour information is encoded by a large, but limited number of receptor neuron types.
3. Most neurons responded to a limited number of compounds (1–5) and showed a marked best response to one of them, whereas additional responses to several other components which seems to be structurally similar, was recorded for some neurons. It suggests that the plant odour receptor neurons are rather narrowly than broadly tuned, and that each neuron is specialized for receiving information about one or a few related compounds.
4. Most neurons responded to monoterpenes, whereas the other neurons responded to compounds of other categories.
5. Both major and minor plant volatile components activated specifically receptor neurons.

     

The seagrass and associated macroalgal vegetation of Gazi Bay (Kenya)

The seagrass and macroalgal vegetation of Gazi Bay (at approximately 50 km south of Mombasa) have been studied by means of 88 relevés along 7 transects. Correlation between the distribution of the seagrasses and some abiotic factors (particle size fractions, chemical composition of the substrate) is not well marked. Nevertheless a general zonation and succession of seagrasses could be established:

1. A transition zone between the mangal and the seagrass beds is covered byBoodleopsis pusilla;
2. the pioneer associationHalophila ovalis +Halodule wrightii forms low sandy bumps at the upper limit of the seagrass beds, but also occurs in the whole midlittoral where sandlayers have recently been accumulated (e.g. on coral platforms);
3. the climax vegetation of the intertidal zone seems to beThalassia hemprichii which sometimes is associated withCymodocea rotundata andC. serrulata, certainly in deeper pools and close to low water mark;Halimeda opuntia,Gracilaria salicornia andG. corticata are also frequent in this vegetation type;
4. from low water at neap tide downwards patches of monospecificEnhalus acoroides vegetation can also occur;
5. from mean low water down to approximately ?1 m mixed meadows ofThalassia, C. serrulata, C rotundata andHalodule uninervis are well developed; the seaweedsHalimeda macrooloba andAvrainvillea obscura are also typical for this zone; locally patches ofSyringodium isoetifolium grow on small bumps andHalophila stipulacea grows as a pioneer on bare sand;
6. from ?1 m downwards the whole lagoon is covered by homogeneous, monospecificThalassodendron ciliatum meadows, locally replaced byE. acoroides.

     

The arthropodBundenbachiellus giganteus from the Lower Devonian Hunsrück Slate, Germany

The large Hunsrück Slate arthropodBundenbachiellus giganteus (Broili, 1929) has been interpreted as a myriapod, a possible arthropleurid, and most recently as a distorted specimen of the arachnomorph arthropodCheloniellon. The Single specimen lacks the head region and is characterised by a narrow trunk bearing a series of biramous appendages with a segmented endopod and filamentous exopod. A reinvestigation demonstrates that it is not referable toCheloniellon but represents a distinct taxon of whichEschenbachiellus wuttkensis Briggs &;Bartels, 2001, also based on a Single Hunsrück Slate specimen, is a junior synonym. Minor features ofStürmer &;Bergström’s (1978) reconstruction ofCheloniellon, which were based on the holotype ofBundenbachiellus giganteus, are revised.     

The distribution ofActinocyclus normanii (Bacillariophyceae) in estuaries: Field observations and laboratory investigations

Combining the results of field observations from the Eider, Elbe, Weser and Ems estuaries and laboratory experiments it was found that:

1. in German North Sea estuaries the tidal freshwater reaches are the main habitat of the diatomActinocyclus normanii.
2. the residence time within the tidal freshwater reaches is a key factor controlling not only seasonal and spatial densities within one estuary, but also density differences between estuaries;
3. A. normanii is well adapted to strongly changing light situations and thus adapted to estuaries with high vertical turbulent mixing and low values of Zeu/Zmix;
4. the downstream limit of the habitat ofA. normanii is mainly determined by light limitation rather than by hyperosmotic stress.