The effect of remating on sperm number in the spermatophores of Teleogryllus commodus (Gryllidae)

Factors controlling sperm production in members of the Orthoptera have not been fully elucidated. In this study, the influence of intermating interval and ad libidum mating on sperm number was investigated in black field crickets (Teleogryllus commodus). Remating at a variety of time intervals was not characterized by a significant change in sperm number compared with the first mating. Ad libitum mating (i.e., continuous availability of unmated females) had two main effects on spermatophore production and sperm number: first, there was a trend toward increased time between copulations with each successive remating, and second, the number of spermatozoa encapsulated in the transferred spermatophore declined after most rematings, with 61.8% of the initial sperm number being produced for the second spermatophore and 51.3% of the initial sperm number being produced for the third. The decrease in mean sperm number was accompanied by increased variance in sperm number in later rematings. This study suggests that males are willing to suffer a decrease in sperm number if a mating opportunity occurs before the completion of sperm production.     

Effects of fire on regional evapotranspiration in the central Canadian boreal forest

Changes in fire regimes are driving the carbon balance of much of the North American boreal forest, but few studies have examined fire‐driven changes in evapotranspiration (ET) at a regional scale. This study used a version of the Biome‐BGC process model with dynamic and competing vegetation types, and explicit spatial representation of a large (10⁶ km²) region, to simulate the effects of wildfire on ET and its components from 1948 to 2005 by comparing the fire dynamics of the 1948–1967 period with those of 1968–2005. Simulated ET averaged, over the entire temporal and spatial modeling domain, 323 mm yr⁻¹; simulation results indicated that changes in fire in recent decades decreased regional ET by 1.4% over the entire simulation, and by 3.9% in the last 10 years (1996–2005). Conifers dominated the transpiration (E_C) flux (120 mm yr⁻¹) but decreased by 18% relative to deciduous broadleaf trees in the last part of the 20th century, when increased fire resulted in increased soil evaporation, lower canopy evaporation, lower E_C, and a younger and more deciduous forest. Well‐ and poorly drained areas had similar rates of evaporation from the canopy and soil, but E_C was twice as high in the well‐drained areas. Mosses comprised a significant part of the evaporative flux to the atmosphere (22 mm yr⁻¹). Modeled annual ET was correlated with net primary production, but not with temperature or precipitation; ET and its components were consistent with previous field and modeling studies. Wildfire is driving significant changes in hydrological processes by affecting mean stand age, forest species, and energy balance. These changes, particularly in poorly drained areas, may control the future carbon balance of the boreal forest.     

Cryopreservation of <Emphasis Type="Italic">Robinia</Emphasis><Emphasis Type="Italic">pseudoacacia</Emphasis>

Cryopreservation of Robinia pseudoacacia explants by vitrification achieved 78% survival following the stepwise preculture of shoot tips in (0.3 + 0.5 + 0.7 M) sucrose with a 80 min incubation in PVS2; compared to 87% survival after desiccation of explants to 30% water content, following 3 days alginate bead (with glycerol and sucrose treatments) preculture in 0.7 M sucrose.     

Involvement of lignin peroxidase in the decolourization of black olive mill wastewaters by Geotrichum candidum

AIM: Decolourization of black olive mill wastewaters (OMW) by depolymerization of phenolic compounds by Geotrichum candidum. METHODS AND RESULTS: Our results show that G. candidum is able to grow on black OMW supplemented with carbon source and nitrogen. The Geotrichum growth decreased the pH and induced a 49% of colour removal when the black OMW was supplemented with glycerol and diammonium tartrate (20 mm ammonium). An improvement of 10% of colour removal was observed when the culture was supplemented with veratryl alcohol. The decolourization was inhibited with glutamate as nitrogen source. CONCLUSION: Our results suggest the potential use of G. candidum in black OMW decolourization and support the concept that lignin peroxidase (LiP) of G. candidum is involved in the depolymerization of phenolic compounds. Significance and Impact of the Study: This is the first report of LiP production by G. candidum on OMW.     

Phylogeography of the black fly Simulium tani (Diptera: Simuliidae) from Thailand as inferred from mtDNA sequences

Intraspecific phylogeography has been used widely as a tool to infer population history. However, little attention has been paid to Southeast Asia despite its importance in terms of biodiversity. Here we used the cytochrome oxidase I gene of mitochondrial DNA (mtDNA) for a phylogeographic study of 147 individuals of the black fly Simulium tani from Thailand. The mtDNA revealed high genetic differentiation between the major geographical regions of north, east and central/south Thailand. Mismatch distributions indicate population expansions during the mid-Pleistocene and the late Pleistocene suggesting that current population structure and diversity may be due in part to the species' response to Pleistocene climatic fluctuations. The genealogical structure of the haplotypes, high northern diversity and maximum-likelihood inference of historical migration rates, suggest that the eastern and central/southern populations originated from northern populations in the mid-Pleistocene. Subsequently, the eastern region had had a largely independent history but the central/southern population may be largely the result of recent (c. 100,000 years ago) expansion, either from the north again, or from a relictual population in the central region. Cytological investigation revealed that populations from the south and east have two overlapping fixed chromosomal inversions. Since these populations also share ecological characteristics it suggests that inversions are involved in ecological adaptation. In conclusion both contemporary and historical ecological conditions are playing an important role in determining population genetic structure and diversity.     

The use of mutagens to increase the efficiency of the androgenic progeny production in <Emphasis Type="Italic">Solanum nigrum</Emphasis>

Pollen embryogenesis was successfully induced in Solanum nigrum L. (2n=6×=72). Stimulation of androgenesis expressed as the frequency of androgenic responsive anthers was observed after 10 and 20 mM ethyl methanesulphonate (EMS), 10 and 20 mM sodium azide (NaN₃) and 0.2 mM N-nitroso-N-methylurea (MNU) treatment applied on seeds for 24 h. The frequency of androgenesis on the medium with sucrose was higher than on the medium with maltose. Androgenic regenerants originated also in the anthers collected from donor plants where survival after mutagenic treatment was lower than 50 %. Green haploid (3x), aneuploid (to 8x) and dihaploid (6x) plants were obtained. The high frequency of aneuploids among androgenic plants is explained by cell division irregularities in microsporial calli.     

Conservation Genetics of the East Pacific Green Turtle (Chelonia mydas) in Michoacan, Mexico

The main continental nesting rookeries of the east Pacific green turtle (EPGT), Chelonia mydas, on the Michoacan (Mexico) coast suffered drastic population declines following intense exploitation in the 1960s--1970s with annual abundance of nesting females plummeting from about 25,000 to an average of about 1400 between 1982 and 2001. Analyses of data from three nDNA microsatellite loci and 400 bp mtDNA control region sequences from a total of 123 nesting females sampled from four Michoacan rookeries found no evidence of population sub-structuring. The recent order of magnitude reduction in the population size shows no apparent impact on genetic diversity in either control region sequences (overall h = 0.48; pi = 0.0036) or microsatellite loci (overall Na = 20.8; Hexp = 0.895). Our estimates of annual effective female population size (Nef; from theta = 2Nemicron) of 1.9-2.3 x 10(3), in spite of being an order of magnitude below historical records, appear to be sufficient to allow recovery of this population without significant loss of genetic diversity. These findings highlight the importance of continued conservation to reverse the decline of this population before it becomes vulnerable to genetic erosion.     

Inhibitory effects on phospholipase A2 and antivenin activity of melanin extracted from Thea sinensis Linn

Antivenin activity of melanin extracted from black tea (MEBT) was reported for the first time. The antagonistic effect of MEBT was evaluated for Agkistrodon contortrix laticinctus (broadbanded copperhead), Agkistrodon halys blomhoffii (Japanese mamushi), and Crotalus atrox (western diamondback rattlesnake) snake venoms administered i.p. to ICR mice. MEBT was injected i.p. immediately after the venom administration in dose of 3 mg per mouse in the same place of venom injection. MEBT demonstrated neutralization effect against all venoms tested. The greatest antivenin effect of MEBT was found against Japanese mamushi snake venom. In this case, half the mice died within 2.5 +/- 0.7 h after injection of 0.9 mg/kg of venom. An immediate injection of MEBT substantially reduced the toxic effect of venom and extended time at the 50% level of survival up to 52.3 +/- 2.3 h. The antivenin activity of MEBT is due to chelating of Ca++ and non-specific binding of phospholipase A2. The inhibitory effect of MEBT on phospholipase A2 assessed for different venoms was similar to that obtained with pure enzyme. Low toxicity of MEBT in combination with its antagonistic activity against different venoms may allow effective life-saving treatment against snakebites. Such application of MEBT is important when identification of the snake is impossible or if specific treatment is unavailable.     

Development of six microsatellite loci for black mangrove (Avicennia germinans)

We developed six new microsatellite loci for the black mangrove (Avicennia germinans), an important member of wetland communities worldwide. Loci showed moderate to high polymorphism and a survey of four locations [Puerto Rico (Jobos Bay and Luquillo), Mexico, French Guyana] revealed clear regional (and local) population structure. All populations were genetically distinct and the two continental populations showed much higher diversity than the two insular Puerto Rican locations. These loci complement those recently published by Nettel et al. (2005 ) and promise to be valuable for characterizing local and regional population dynamics in the black mangrove.     

Influence of weather conditions on the flight of migrating black storks

This study tested the potential influence of meteorological parameters (temperature, humidity, wind direction, thermal convection) on different migration characteristics (namely flight speed, altitude and direction and daily distance) in 16 black storks (Ciconia nigra). The birds were tracked by satellite during their entire autumnal and spring migration, from 1998 to 2006. Our data reveal that during their 27-day-long migration between Europe and Africa (mean distance of 4100 km), the periods of maximum flight activity corresponded to periods of maximum thermal energy, underlining the importance of atmospheric thermal convection in the migratory flight of the black stork. In some cases, tailwind was recorded at the same altitude and position as the birds, and was associated with a significant rise in flight speed, but wind often produced a side azimuth along the birds'' migratory route. Whatever the season, the distance travelled daily was on average shorter in Europe than in Africa, with values of 200 and 270 km d⁻¹, respectively. The fastest instantaneous flight speeds of up to 112 km h⁻¹ were also observed above Africa. This observation confirms the hypothesis of thermal-dependant flight behaviour, and also reveals differences in flight costs between Europe and Africa. Furthermore, differences in food availability, a crucial factor for black storks during their flight between Europe and Africa, may also contribute to the above-mentioned shift in daily flight speeds.