Global-scale data on the Oligocene to Recent planktic foraminifers and coccoliths from the tropical Pacific and Atlantic Oceans are employed for quantitative testing of alternative models (Red Queen and Stationary Hypotheses) of the relationship between speciation rates, extinction rates, taxonomic diversity, abiotic events, and history of the paleosystem. The results demonstrate that although ...

The Mesozoic, mid-Cretaceous (Barremian to Cenomanian) deposits of southern Croatia comprise a succession of shallow tropical-water, inner-platform deposits that formed on a Bahama-type isolated Adriatic carbonate platform in the Dinarides. This succession is dominated by benthic foraminifers and dasycladalean algae, and is exposed in a nearly continuous outcrop section on the islands and along...

Atmospheric hyperoxia, with pO(2) in excess of 30%, has long been hypothesized to account for late Paleozoic (360-250 million years ago) gigantism in numerous higher taxa. However, this hypothesis has not been evaluated statistically because comprehensive size data have not been compiled previously at sufficient temporal resolution to permit quantitative analysis. In this study, we test the hy...

this study was carried out to identify fusarium species associated with sugar beet root rot and yellows. pathogenicity of fusarium oxysporum, the causal agent of fusariumyellows of sugar beet was also investigated. samples of infected roots were collected from fields in major sugar beet producing areas in khorasan province during 1999-2000. infected roots were washed, surface sterilised and pla...

hexachlorocyclohexane, an organochlorine insecticide has been used in agriculture and public health programmes since a very long time. it is very resistant to degradation and thus accumulates in the environment for long time. a microbial consortium was developed in our laboratory which could degrade hexachlorocyclohexane very efficiently in water. a study was carried out to understand the biode...

micro flora of the effluents from a dairy factory in tehran(pegah dairy processing plant) were isolated and screened for their ability to reduce the organic matter content and cod of the effluents. 10 bacteria were selected due to  reduction in cod content from the 4th to 6th day of incubation at 30 °c and  ph =11. highest cod reduction were obtained by two isolates, bp3 and bp4, 70.7 % and 69....

plants are potent biochemists; biologically active compounds present in the medicinal plants have always been ofgreat interest to scientists working in this field. thus, the aim of the current study was to screen the antimicrobial activity of acacia nilotica, ziziphus mauritiana, bauhinia variegate and lantana camara against some selected clinical isolated strains. although previous studies hav...

the plant kingdom constitutes a source of new chemical compounds, which may be important due to their potential uses in medicine, or their other biological properties. in this study, the effects of galbanic acid (ga), a sesquiterpene coumarin from roots of ferula szowitsiana, were investigated as a modulator of antibiotic resistance in clinical isolates of staphylococcus aureus. isolates of s. ...

Colibacillosis caused by avian pathogenic Escherichia coli (APEC) is an economic threat to the poultry industry throughout the world. Some of the virulence genes may enhance the ability of E. coli isolates to grow in the tissues of broilers. The APEC strains are assigned to a few distinct phylogenetic groups. The purpose of the present study was to detect the virulence genes a...