New distribution limits of seagrass beds in West Africa

The southern limit of the distribution of seagrass species along the west coast of Africa is not yet clearly defined. In March 2008 an expedition was organized in Senegal to search for seagrass beds from Dakar (14°45'15" N, 17°30'31" W) southwards to Tabakouta–Delta du Saloum (13°46'59" N, 16°28'42" W). Cymodocea nodosa and Halodule wrightii were observed in sandy areas of some protected bays of Dakar, around Sarène (14°16'18" N, 16°54'17" W), Joal Fadiouth (14°09'08" N, 16°50'03" W) and the Bamboung–Sourou area (13°50'08" N, 16°33'09" W), and they probably occur all along the coast of Senegal and beyond, perhaps much further south as well.     

Elevation of the heat resistance of Salmonella typhimurium by sublethal heat shock

The survival of Salmonella typhimurium after a standard heat challenge at 55°C for 25 min increased by several orders of magnitude when cells grown at 37°C were pre-incubated at 42°, 45° or 48°C before heating at the higher temperature. Heat resistance increased rapidly after the temperature shift, reaching near maximum levels within 30 min. Elevated heat resistance persisted for at least 10 h. Preincubation of cells at 48°C for 30 min increased their resistance to subsequent heating at 50°, 52°, 55°, 57° or 59°C. Survival curves of resistant cells were curvilinear. Estimated times for a '7D' inactivation increased by 2.6- to 20-fold compared with cells not pre-incubated before heat challenge.     

Heat resistance of Listeria: strain differences and effects of meat type and curing salts

The heat resistances of 27 strains of Listeria monocytogenes and two strains of L. innocua were compared in broth heated at 57°C. No strain was exceptionally resistant. The heat resistance of a representative isolate of L. monocytogenes was compared in fresh and cured beef and chicken, and an equation was derived to predict the time necessary to achieve a '7D' inactivation at temperatures between 50 and 70°C.     

Ecohydrology of a seasonal wetland in the Rift Valley: ecological characterization of Lake Solai

The following research describes through an ecohydrological approach, the first assessment of the ecology of Lake Solai, with a particular emphasis on the vegetation. Lake Solai is located 50 km north of Nakuru in the Rift Valley in Kenya at E36°80'–36°84' to N00°05'–00°08'. It is a shallow lake that follows a very peculiar seasonal water regime, and that faces conflicts between agriculture and conservation water users. In the upper catchment, an overview of the agricultural practices was implemented and river water uses were identified to assess river flows. Crops/grassland and woodland/shrubland were the major land uses, covering c. 65% of the catchment. Closer to the lake, vegetation samples were collected around the lake together with samples of environmental factors such as soil and water quality. Thirteen vegetation communities were identified within four main zonations: forest, grassland, river inlet and rocky outcrop. These communities showed abundance, distribution and diversity determined mostly by the human pressures, the flooding periods and the salinity. Cynodon , Cyperus and Sporobolus genera were the most abundant.     

The effect of climatic gradients, topographic variation and species traits on the beta diversity of rain forest trees

Aim  We assessed the rates of turnover of tree species with distance (beta diversity) in wet forests of the Western Ghats (WG) complex of India to see whether climate, topographic variation or species traits influence beta diversity.
Location  The Western Ghats is a chain of mountains about 1600 km in length, running parallel to the western coast of the Indian Peninsula from above 8° N to almost 21° N latitude.
Methods  We used data from 60 small plot inventories concentrated in three regions: the southernmost part of the Western Ghats (SWG) (8°24' to 9°37' N), the Nilgiri Hills (11°12' to 11°14' N), and the central Western Ghats (CWG) (12°32' to 14°51' N). We used Sorensen's index (SI) to estimate the similarity in species composition between two plots and regressed SI against the logarithm of the distance between plots to assess beta diversity. A bootstrapping procedure provided confidence intervals for regression coefficients. To test for the effects of climate, we regressed seasonality differences between plots against SI for low-elevation (< 800 m) plots along the north–south axis, and all plots in the SWG. We assessed the impact of the rainfall gradient in the Kogar region.
Results  Among all three regions, beta diversity was highest along the latitudinal axis, and along the rainfall gradient in the Kogar region. Differences in seasonality between sites were strongly related to beta diversity along the north–south seasonality gradient and within the SWG. Within the three regions, beta diversity was highest in the region with the strongest rainfall gradient and lowest for the topographically heterogeneous SWG. Beta diversity did not differ between forest strata and dispersal modes.
Main conclusions  We conclude that climate, particularly seasonality, is probably the primary driver of beta diversity among rain forest trees of the Western Ghats complex.     

Mugil cephalus L.—a first British record and a further 5°N

The occurrence of a 29 mm juvenile Mugil cephalus in the Camel estuary at 50°30' N represents the first British record of this widespread tropical and subtropical species. Its origins, however, are obscure.     

利安德水鼩在中国地理分布范围的讨论与修订

利安德水鼩很长时间被认为是喜马拉雅水鼩的亚种，但近年来的研究发现利安德水鼩是进化关系上与日本水鼩更加接近的独立物种。而喜马拉雅水鼩一直被认为是分布区横跨古北界和东洋界广域分布的物种，但基于Cyt b基因序列测定和系统进化关系的构建，我们确定最近在四川、浙江和湖南等地采集的水鼩标本均为利安德水鼩。基于基因序列和对馆藏标本的比对，我们修订喜马拉雅水鼩和利安德水鼩在中国的分布。四川、湖北、湖南、陕西、贵州、广西、福建、台湾、浙江等地区都是利安德水鼩的分布区，而喜马拉雅水鼩在中国确定的分布区仅在云南。这一分布格局很可能是由于在地形地貌的影响下产生隔离分化的结果。     

DISTRIBUTION OF THE PYGMY RIGHT WHALE, CAPEREA MARGINATA, IN THE AUSTRALASIAN REGION

The latitudinal range of all records of sightings ( n = 9), and live strandings and carcasses ( n = 180) of Caperea marginata in the Australasian region was 32°00'–47°00'S. Records were concentrated on the edge of the South Australian gulfs, around Tasmania, at Stewart Island, in Cook Strait, and in the Auckland area. Limited data suggest that these may be related to planktonrich waters nearby. Body lengths ranged from 198 to 650 cm. Overall sex ratio was 0.70 (males: females). In regions north of about 41°S, juveniles (preweaning) made up 41% of the records and subadults (postweaning) were rare (13%). In regions south of about 41°S subadults (36%) were proportionately more abundant than juveniles (17%). Neonates were recorded from 35°37' to 47°00'S. Adults were found throughout the latitudinal range of the species in Australasia. The diet of the pygmy right whale included copepods and small euphausiids. Behavior consistent with feeding has been observed in coastal waters of Australia.     

MARINE BACTERIA OF CARDIGAN BAY. I. BACTERIA OF AN OFF-SHORE AREA

SUMMARY: A study of marine bacteria from a fixed off-shore area in Cardigan Bay showed there was little significance in the variation between numbers from different levels within 8 fathoms deep. There was a suggestion of seasonal variation in surface water in colony counts at 15–18°. In general, the bacterial content was highest over the summer months, but showed little direct correlation with temperature, pH or light.
Strains were mainly obligate halophytes and small Gram-negative rods predominated (96%). Nearly 50% of strains isolated liquefied gelatin; otherwise, biochemical reactions were weak. The proportion of pigmented strains was low.
Alien bacteria were present in irregularly varying numbers in all samples and showed no seasonal variation. Coli-aerogenes strains were recorded in small numbers, at all depths and in all seasons, but Bact. coli type I only rarely occurred.     

Emergence of Baltic salmon, Salmo salar L., in relation to temperature: a laboratory study

Emergence pattern and developmental status at emergence of Baltic salmon fry from the Umeälven hatchery stock (63°50'N, 20°25'E) were studied at 6, 10 and 12°C in the laboratory. The number of days and degree days from hatching to 50% emergence decreased exponentially with increasing temperature. Synchronization of emergence increased with temperature. Optimal temperature for incubation of yolk-sac alevins was 10°C, which resulted in the largest fry at emergence and the lowest death rate. Fry kept at 6°C had the lowest mean weight and at 12°C the highest death rate. The fry emerged at an earlier developmental state with more yolk at 12°C than at 6°C. The Baltic salmon had a faster developmental rate during the gravel-phase, as compared to more southern Atlantic salmon populations.     

The influence of the rate of temperature change on the activation of dormant seeds of Rumex obtusifolius L.

1. One temperature shift from 20 to 30°C in darkness induces 30–40% germination in Rumex obtusifolius seeds. The same germination percentages are found with heat treatment varying between 1 and 6h duration, indicating that the total heat sum of the temperature shift is not important.
2. Germination is greatly enhanced by three consecutive heat shifts of 1h at 30°C separated by 1h periods at 20°C.
3. The seeds are activated to a small extent after a slow warming (+2°Ch^–1) from 20 to 30°C, followed by incubation for 1h at 30°C. Germination is much higher after rapid heating (+10°Ch^–1) to 30°C, followed by 1h incubation at this temperature. Repeated fast heating treatments on four consecutive days enhances germination. Moderately rapid heatings (+3·3°Ch^–1) give intermediate results.
4. The rate of cooling does not influence the germination percentage. Cooling alone cannot induce germination.
5. Heating alone from 15 to 25°C without cooling also activates germination. In this temperature range the seeds are more activated by rapid warming than by slow warming.
6. The ecological relevance of the response to different warming rate is discussed. The insensitivity of seeds to a slow warming might keep deeply buried seeds in a dormant stage.     

Reversible change in embryonic diapause intensity by mild temperature in the Chinese rice grasshopper, Oxya chinensis

The effects of temperature on maintenance and termination of embryonic diapause were investigated in Jining (35.4°N, 116.6°E) and Sihong (33.5°N, 118.2°E) strains of the Chinese rice grasshopper, Oxya chinensis Thunberg (Orthoptera: Catantopidae). Eggs of both strains entered diapause when incubated at 30, 25, or 20 °C. Chilling at 8 °C had an evident effect on diapause termination and almost all eggs chilled for 60 days ended diapause development. Chilling of eggs at 8 °C for only 20 days failed to result in any hatching at 20 °C, suggesting that such level of chilling was not enough to induce diapause termination. However, the treatment combining incubation of eggs at 30 °C for varying lengths of time with subsequent incubation to 20 °C had a distinct effect on the completion of diapause of the eggs. The results indicate that there were two temperature optima, that is, low temperature (chilling) and high temperature, for diapause development in this grasshopper species. Incubation of chilled eggs at 20 °C for 5–15 days followed by further incubation at 25 °C reduced termination of diapause significantly compared with the eggs only chilled at 8 °C. Exposure of eggs chilled at 8 °C to a pulse of 25 °C from 1 to 7 days, separated by a 20-day interval at 8 °C, resulted in a decrease in the percentage of successfully hatched eggs as the length of the pulse of 25 °C increased. The results suggest that diapause intensity may be restored at moderately high temperatures. This reversible change in diapause intensity would play an important role in maintaining diapause before winter.     

Ventilatory mechanisms and the effect of hypoxia and temperature on the embryonic lesser spotted dogfish

Small, intermediate and large-sized embryos of the dogfish Scyliorhinus canicula utilize different ventilatory methods; small and intermediate embryos rely on body movement alone to stir either the jelly or sea water in the capsule, large embryos use conventional pharyngeal pumping to pump water through the case. The effects of environmental changes in O₂ tension (0.5–100% air saturation) and temperature (6–18°C) upon ventilatory mechanisms in the developing embryo in situ were studied using non-invasive ultrasonography. All three embryo classes increased ventilation rate with rising temperature: for small embryos, y=2.02x+3.295 ( P <0.01); for intermediate embryos, y=3.51x+0.395 ( P <0.01); and for large embryos, y=3.81x+9.39 ( P <0.01); where y=ventilatory frequency (tail beats min⁻¹ or pump cycles min⁻¹) and x=temperature (°C). Q ₁₀ (6–16°C)=5.0, 2.45, and 2.08 for small, intermediate and large embryos, respectively; corresponding Q ₁₀ (8–18°C) values were 2.09, 2.62, and 2.02. It is suggested that the extreme response of small embryos to 6°C is related to a different state of development in either chemoreceptors or muscle blocks. There was no significant change in ventilatory frequency induced by chronic (2 h) hypoxia. Dogfish embryos are oxyconformers at 8°C but oxyregulators at higher temperatures. Water flow through an eggcase occupied by a large embryo was studied also. Water enters the open eggcase of a large embryo, drawn in by the buccal/opercular pump of the respiring embryo, via holes at the posterior end of the eggcase. Expired water exits holes at the anterior end of the eggcase. The mean residence time for water in the case is 50 s at 8°C, giving a transit velocity of 1.36 mm s⁻¹.     

THE BEHAVIOUR OF THE WILLOW WARBLER PHYLLOSCOPUS TROCHILUS IN CONTINUOUS DAYLIGHT

Willow Warblers Phylloscopus trochilus at Wytham, Oxford (51° 46' N., 1° 15' W.), start to sing around sunrise, in late April to early June. In the continuous daylight at Neiden, East Finnmark (69° 42' N., 29° 25' E.), they do not sing all the time, but in late June to late July start singing between 22.45 and 01.45 hrs., the start becoming progressively later as the season draws on. At Neiden, nest visits start some time after song (01.00–02.30), and this is probably also true at Wytham.
The influence of environmental variables on the starts of the two cycles is discussed. It is concluded that song starts at Wytham when light intensity has risen above a certain threshold level, and at Neiden, when it has reached a minimum value or has started to rise again. It is suggested that the Neiden birds react to the closest approximation of their light intensity cycle to that at dawn further south. The end of daily song at Neiden may be controlled by internal factors. It is suggested that the start of the Neiden nest-visit cycle is controlled by light intensity, but modified by temperature effects. The possibility that the environment affects the bird indirectly, via its brood or food, can be ruled out. The functional significance of the retention of activity lulls in the continuous daylight of the Arctic summer is discussed.
The daily song-starts of the Garden Warbler Sylvia borin , Brambling Fringilla montifringilla , and Yellowhammer Emberiza citrinella , follow the same pattern as those of the Willow Warbler. The Redwing Turdus musicus often has no daily song lull; its nest-visit lull begins and ends well before midnight. The significance of this is discussed.     

Estrogen-like activity of glabrene and other constituents isolated from licorice root

Licorice root extract and its major isoflavan, glabridin, exhibited varying degrees of estrogen receptor (ER) agonism in different tissues in vitro and in vivo. Animals fed with licorice extract, compared with estradiol and glabridin, showed an increase in creatine kinase (CK) activity, a known marker for estrogen responsive genes, which was higher than expected from the levels of glabridin in the extract. This led us to test for other components that may contribute to this strong estrogen agonist activity. Results indicated that glabrene and isoliquiritigenin, (2',4',4-three hydroxy chalcone) (ILC) in the licorice extract can bind to the human ER with higher affinity (IC50, 1 and 0.5 microM) than glabridin (IC50, 5 microM). The stimulatory effects of glabrene in vivo were tissue specific and similar to those of estradiol. The effect of increasing concentrations of glabrene and ILC on the growth of breast tumor cell were biphasic. Both showed an ER-dependent growth-promoting effect at low concentrations (10 nM-10 microM), and ER-independent antiproliferative activity at concentrations >15 microM. This is the first study to indicate that glabrene, an isoflavene exerted varying degrees of ER agonism in different tissues.     

Cloning, purification and characterization of a thermostable amylosucrase from Deinococcus geothermalis

Amylosucrase is a transglucosidase that catalyses the synthesis of an amylose-type polymer from sucrose, an abundant agro-resource. Here we describe a novel thermostable amylosucrase from the moderate thermophile Deinococcus geothermalis (DGAS). The dgas gene was cloned and expressed in Escherichia coli . The encoded enzyme was purified and characterized. DGAS displays a specific activity of 44 U mg⁻¹, an optimal temperature of 50 °C and a half-life of 26 h at 50 °C. Moreover, it produces an α-glucan at 50 °C, with an average degree of polymerization of 45 and a polymerization yield of 76%. DGAS is thus the most active and thermostable amylosucrase known to date.     

Effect of temperature on the vegetative growth of type and field strains of Bacillus cereus

Growth of eight selected potentially pathogenic strains of Bacillus cereus was evaluated in a rich medium at different temperatures. No strain grew at 50°C; maximal growth-permissive temperatures were in the range 46–50°C for six strains and under 46°C for one strain. Faster growth occurred at 42°C. Growth may be delayed at 20°C, where the lag phase can reach 7 h. Furthermore at 20°C, cells generally show an aggregation immediately in the early exponential stage, except for two strains. Owing to this aggregation, growth is more difficult to estimate by turbidimetry at lower temperatures. These data describe the behaviour of type and field strains between 50° and 20°C and can help the prediction of shelf-life of potentially contaminated products.     

Folding of staphylococcal nuclease: kinetic studies of two processes in acid renaturation

The folding of acidified staphylococcal nuclease, upon neutralization, was studied in a stopped-flow spectrofluorometer by measuring the increase in tryptophanyl fluorescence during renaturation. At 25 °C and 0.1 ionic strength, the fluorescence change may be described by two first-order rate processes with half-times of 55 and 350 msec. No significant change in either rate was effected on varying the initial pH from 3.2 to 3.8 (corresponding to 0 to 50% levels of folding) or the initial ionic strength from 0.001 to 0.1. In contrast, the over-all rate of folding is dependent upon temperature. The half-time of the slower rate process decreases from 600 msec at 13 °C to 150 msec at 38 °C; the half-time of the faster rate process does not change significantly over this temperature range. These results suggest that the two processes may correspond to a sequence involving nucleation of ordered structure followed by the formation of hydrophobic interactions. Possible structural correlates of these processes are discussed with respect to the crystallographic model of this protein.     

Effect of temperature on the hatching time of eggs of Ephemerella ignita (Poda) (Ephemeroptera:Ephemerellidae)

SUMMARY. Eggs of Ephemerella ignita (Poda) were kept at eight constant temperatures (range 5.9–19.8°C) in the laboratory. Over 85% of the eggs hatched in the temperature range 10.0–14.2°C but the percentage decreased markedly to 39% at 5.9°C and 42% at 19.8°C. Hatching time (days after oviposition) decreased with increasing water temperature over the range 5.9–14.2°C and the relationship between the two variables was well described by a hyperbola. Therefore, the time taken for development was expressed in units of degree-days above a threshold temperature. Mean values (with 95%CL) were 552 (534–573) degree-days above 4.25°C for 10% of the eggs hatched, 862 (725–1064) degree-days above 3.57°C for 50% hatched and 1383 (1294–1486) degree-days above 3.14°C for 90% hatched. These values can be used to predict hatching times at temperatures below 14.68°C for 10% hatched, 14.54°C for 50% hatched and 14.45°C for 90% hatched. At higher temperatures, the hatching time and the number of degree-days required for development both increased with increasing temperature. Equations were developed to estimate the number of degree-days required for development at these higher temperatures.
Eggs were also placed in the Wilfin Beck, a small stony stream in the English Lake District. Maximum and minimum water temperatures were recorded in each week and the summation of degree-days was used to predict the dates on which 10%, 50% and 90% of the eggs should have hatched. There was good agreement between these estimates and the actual hatching times. Only 10–15% of the eggs hatched between October and late February with most of the eggs hatching in March, April and May. Nymphs hatching in October and November probably did not survive the winter.