Mesozooplankton of the Kosi Bay lakes,South Africa

The Kosi coastal lake system, a chain of four interconnected basins, is located in the subtropical north-eastern corner of South Africa. Little information is available on zooplankton of the system and the main aim of this study is to report on zooplankton samples collected during 2002 and 2003. The set of samples consists of seasonal, subsurface mesozooplankton samples that were collected during nighttime in each of the lakes. A well-developed salinity gradient was evident along the interconnected lakes in the subsurface water during all seasons, ranging from freshwater in the upper lake Amanzamnyama to a maximum of 22 recorded in Lake Makhawulani. The zooplankton community structures of the lakes reflected the salinity gradient of the system, with some coastal marine taxa recorded in the lakes closer to the mouth and only freshwater taxa recorded in Lake Amanzamnyama. Mesozooplankton diversity and abundance were relatively low compared to other estuarine systems along the eastern coast of South Africa. The dominant taxa were calanoid copepods Acartiella natalensis and Pseudodiaptomus stuhlmanni and the mysid Mesopodopsis africana in the lower lakes, whereas cyclopoids Mesocyclops sp. and Thermocyclops sp. dominated the freshwater lake Amanzamnyama.     

Photodynamic inactivation of Lasiodiplodia theobromae: lighting the way towards an environmentally friendly phytosanitary treatment

The fungus Lasiodiplodia theobromae is one of the main causal agents of trunk canker and dieback of grapevine. The objective of this work was to evaluate the efficiency of photodynamic inactivation (PDI) of L. theobromae with synthetic and natural photosensitizers and irradiation with either sunlight or artificial photosynthetically active radiation. Although the growth of the mycelium could not be completely prevented with natural sunlight irradiation, phenothiazine dyes (methylene blue, MB; toluidine blue O, TBO), riboflavin and a cationic porphyrin (Tetra-Py⁺-Me) caused complete inhibition under continuous irradiation with artificial light. Free radicals were the main cytotoxic agents in the PDI with MB, indicating the predominance of the type I mechanism. PDI with MB or Tetra-Py⁺-Me may represent a promising approach for the sanitation of vine material in greenhouse nurseries, in order to reduce the risk of infection upon grafting.     

Fuel ethanol after 25 years

After 25 years, Brazil and North America are still the only two regions that produce large quantities of fuel ethanol, from sugar cane and maize, respectively. The efficiency of ethanol production has steadily increased and valuable co-products are produced, but only tax credits make fuel ethanol commercially viable because oil prices are at an all-time low. The original motivation for fuel-ethanol production was to become more independent of oil imports; now, the emphasis is on its use as an oxygenated gasoline additive. There will only be sufficient, low-cost ethanol if lignocellulose feedstock is also used.     

Effect of polyamines and basic proteins on cleavage of DNA by restriction endonucleases

We have investigated the effect of the polyamines spermine, spermidine, and putrescine and the prokaryotic histone-like proteins NS1 and NS2 on the restriction endonuclease EcoRI catalyzed cleavage of plasmid and bacteriophage DNAs. At low concentrations of spermine and spermidine, the rate of DNA cleavage by EcoRI is increased, while high concentrations of spermine as well as of spermidine are inhibitory. These phenomena are also observed with other restriction endonucleases. They are, therefore, probably due to the interaction of the polyamines with the DNA. Putrescine does not have such an effect within the concentration range investigated. Remarkably, low concentrations of spermine and spermidine very efficiently suppress EcoRI activity. An inhibition of the EcoRI-catalyzed cleavage of DNA is also observed with NS1 and NS2, an effect that can be mimicked with other basic proteins that interact with DNA. The results are discussed in terms of the mechanism of restriction in vivo.     

Photosynthetic traits and water use of tree species growing on abandoned pasture in different periods of precipitation in Amazonia

Pasture soils in the Amazon become unsustainable after a short period of use, typically being replaced by emergent secondary vegetation (capoeira). The aim of this research was to investigate the photosynthetic capacity and water use in the most common tree species (Vismia japurensis, Vismia cayennensis, Bellucia grossularioides, Laetia procera, and Goupia glabra) in successional chronosequence. This study was carried out in secondary vegetation area with ages that vary between 1 and 19 years. Responses of gas exchange were determined during different periods of precipitation. The gas exchange decreased with advancing age of the vegetation (1–19 years), except for G. glabra. Negative relationships of P _Nmax as a function of aging observed for V. japurensis, V. cayennensis, B. grossularioides, and L. procera exhibited r ² equal to 0.59, 0.42, 0.33, and 0.58, respectively. The species of Vismia showed higher values for photosynthetic parameters in relation to other species across the chronosequence. Overall, there were differences in gas exchange only for some species between the different periods of precipitation. Therefore, our results suggest a distinct pattern of photosynthetic responses to species in early succession. Light decrease can exert a decisive role to reduce the photosynthetic rates in secondary succession species. On the other hand, the results of WUE showed weak evidence of changes for the species during dry and rainy periods in the abandoned pasture in central Amazonia.     

Complete genome sequence of Corynebacterium pseudotuberculosis strain CIP 52.97, isolated from a horse in Kenya

In this work, we report the whole-genome sequence of Corynebacterium pseudotuberculosis bv. equi strain CIP 52.97 (Collection Institut Pasteur), isolated in 1952 from a case of ulcerative lymphangitis in a Kenyan horse, which has evidently caused significant losses to agribusiness. Therefore, obtaining this genome will allow the detection of important targets for postgenomic studies, with the aim of minimizing problems caused by this microorganism.     

Acetate-induced apoptosis in colorectal carcinoma cells involves lysosomal membrane permeabilization and cathepsin D release

Colorectal carcinoma (CRC) is one of the most common causes of cancer-related mortality. Short-chain fatty acids secreted by dietary propionibacteria from the intestine, such as acetate, induce apoptosis in CRC cells and may therefore be relevant in CRC prevention and therapy. We previously reported that acetic acid-induced apoptosis in Saccharomyces cerevisiae cells involves partial vacuole permeabilization and release of Pep4p, the yeast cathepsin D (CatD), which has a protective role in this process. In cancer cells, lysosomes have emerged as key players in apoptosis through selective lysosomal membrane permeabilization (LMP) and release of cathepsins. However, the role of CatD in CRC survival is controversial and has not been assessed in response to acetate. We aimed to ascertain whether LMP and CatD are involved in acetate-induced apoptosis in CRC cells. We showed that acetate per se inhibits proliferation and induces apoptosis. More importantly, we uncovered that acetate triggers LMP and CatD release to the cytosol. Pepstatin A (a CatD inhibitor) but not E64d (a cathepsin B and L inhibitor) increased acetate-induced apoptosis of CRC cells, suggesting that CatD has a protective role in this process. Our data indicate that acetate induces LMP and subsequent release of CatD in CRC cells undergoing apoptosis, and suggest exploiting novel strategies using acetate as a prevention/therapeutic agent in CRC, through simultaneous treatment with CatD inhibitors.     

Soils from intercropped fields have a higher capacity to suppress black root rot in cassava,caused by Scytalidium lignicola

The objective of the present study was to evaluate the natural suppressive capacity of soils from forest, and monocropping and intercropping systems, against root rot, caused by Scytalidium lignicola, in a greenhouse experiment. We used soils from a tropical dry forest (FOR) and two intercropping and two monoculture systems. The first intercrop was maize and beans (CORNCOWP), and the second intercrop was cassava, pigeon peas and beans (CASPIGPCOWP). The first monoculture was beans, and the second was passion fruit. The intercropping soils showed a higher capacity to suppress black root rot in cassava than the monoculture because such soils were able to reduce disease severity by about 50%. Bean soil in the monoculture showed less microbial biomass carbon than in the intercrop, with means of 10.05 and 38.2 mg/kg, respectively. The higher density of bacteria and fungal populations, microbial biomass, urease and arylsulphatase activities correlated with a decrease in disease severity. Soils from the intercrops produced changes in soil quality, primarily in the population and density of microorganisms, enzymatic activities, total organic carbon and nutrients, reducing disease severity in cassava plants. These effects were validated by multivariate principal component analysis and showed three distinct groups: one FOR, one intercropping and one monocropping. The majority of vectors were in the direction of FOR and intercropping soils. We have provided some of the first data related to the beneficial effects of intercropping on the suppression of black root rot in cassava, which is validated through different attributes.     

Linking warming effects on phenology,demography, and range expansion in a migratory bird population

Phenological changes in response to climate change have been recorded in many taxa, but the population‐level consequences of these changes are largely unknown. If phenological change influences demography, it may underpin the changes in range size and distribution that have been associated with climate change in many species. Over the last century, Icelandic black‐tailed godwits (Limosa limosa islandica) have increased 10‐fold in numbers, and their breeding range has expanded throughout lowland Iceland, but the environmental and demographic drivers of this expansion remain unknown. Here, we explore the potential for climate‐driven shifts in phenology to influence demography and range expansion. In warmer springs, Icelandic black‐tailed godwits lay their clutches earlier, resulting in advances in hatching dates in those years. Early hatching is beneficial as population‐wide tracking of marked individuals shows that chick recruitment to the adult population is greater for early hatched individuals. Throughout the last century, this population has expanded into progressively colder breeding areas in which hatch dates are later, but temperatures have increased throughout Iceland since the 1960s. Using these established relationships between temperature, hatching dates and recruitment, we show that these warming trends have the potential to have fueled substantial increases in recruitment throughout Iceland, and thus to have contributed to local population growth and expansion across the breeding range. The demographic consequences of temperature‐mediated phenological changes, such as the advances in lay dates and increased recruitment associated with early hatching reported here, may therefore be key processes in driving population size and range changes in response to climate change.     

Molecular analysis of the rDNA ITS-1 intergenic spacer in Drosophila mulleri,D. arizonae,and their hybrids

We analyzed the ITS-1 spacer region of the rDNA in Drosophila mulleri and D. arizonae, two sibling species belonging to the mulleri complex (repleta group) and in hybrids obtained in both cross directions. In spite of several previous studies showing the incompatibility of crosses involving D. arizonae females and D. mulleri males, we were able to obtain hybrids in this direction. Complete ITS-1 region was amplified using primers with homology at the 3'-end of the 18S rDNA and the 5'-end of the 5.8S rDNA genes. Our data demonstrated that D. mulleri and D. arizonae can be differentiated as they present a difference in length for the ITS-1 region. The amplified fragment for this region in D. mulleri has a length of 600 bp, whereas in D. arizonae this fragment is about 500 bp. It was also observed that male and female hybrids obtained in both cross directions present two amplified fragments, confirming the location of the ribosomal cistrons in the X chromosomes and microchromosomes of both parental species.