Revisiting Ross and Sims (1971): toward a molecular phylogeny of the Biddulphiaceae and Eupodiscaceae (Bacillariophyceae)

The ocellate and pseudocellate diatoms in the Eupodiscaceae and Biddulphiaceae (respectively) are common inhabitants of the marine littoral (and plankton zone) with a rich fossil history making them important components of marine stratigraphic studies and good candidates for molecular dating work. These diatoms are important for un‐derstanding the phylogeny of the diatoms as a whole, as molecular phylogenies have blurred the traditional distinction between the pennate and multipolar non‐pennate diatoms. However, the convoluted taxonomic history of these groups has the potential to disrupt both stratigraphic and molecular dating studies. Although efforts have been made to examine frustule morphology of several ocellate and pseudocellate diatoms and develop a morphological scheme to define genera, very little work has been done to determine how these groups are interrelated. In this study, we use nuclear and chloroplast molecular markers to construct a phylogeny of a diverse sampling of Eupodiscaceae and Biddulphiaceae taxa. The ocellus‐bearing taxa (Eupodiscaceae) are monophyletic, and thus the ocellus may be a useful character in delimiting the Eupodiscaceae, the Biddulphiaceae are polyphyletic and scattered across a number of lineages of multipolar non‐pennate diatoms. Hypothesis testing aimed at assessing the likeliness of several morphology based hypotheses against the molecular data highlights uncertainty in both types of data. We present evidence that there are monophyletic genera within both the Biddulphiaceae and Eupodiscaceae, and recommend the taxa within the Odontella mobilensis/sinensis/regia clade be transferred to a new genus: Trieres Ashworth & Theriot.     

Cell surface properties of Pseudomonas stutzeri in the process of diesel oil biodegradation

Pseudomonas stutzeri, isolated from crude oil-contaminated soil, was used to degrade diesel oil. Of three surfactants, 120?mg rhamnolipids 1(-1) significantly increased degradation of diesel oil giving 88% loss after 14?days compared to 54% loss without the surfactant. The system with rhamnolipids was characterised by relatively high particle homogeneity. However, the addition of saponins to diesel oil caused the cells to aggregate (the polydispersity index: 0.542) and the biodegradation of diesel oil was only 46%. The cell yield was 0.22?g?l(-1).     

Degradation stages of the oak forests in the area of Algiers

Long lasting human impact on the natural Mediterranean vegetation is the reason for its degradation. Uncontrolled felling of trees, fire and overgrazing are the most important ecological causes of this process.Geobotanical investigations made in the area of Algiers facilitated the characterization of degradation changes in the structure of vegetation and in the floristic composition in all the degradation stages.Under the influence of the degradation factors, mentioned above, the oak forests, growing on different, more or less calcareous substrates, are transformed into various shrub formations, mainly into many types of maquis and garrigue. The floristic composition of these communities is given in Table 2.Further degradation leads to widespread Cistus-formations and then to palmitto, a formation created by the dwarf palm (Chamaerops humilis).When the anthropopressure becomes stronger even this dwarf palm retreats. Loose swards, replacing the palmitto formation, often cannot stop the subsequent degradation. Bare rock is the extreme, relatively rare stage of forest degradation in this area.The most common form of natural regeneration is the invasion of Pinus halepensis, observed in all degradation stages identified. This pine is also one of trees, most commonly planted on mountain slopes to prevent their erosion.     

A novel approach to the generation of antibodies against phylogenetically preserved sperm antigens

Conventional methods for immunization of laboratory animals against human spermatozoa proved not to be efficient enough to identify phylogenetically conserved sperm-specific antigens. A combination of vasectomy and subcutaneous administration of autologous testis homogenates was tested in 5 New-Zealand rabbits, and in 7 Long-Evans and 8 Spraque-Dawley rats in an attempt to induce an autoimmune response against such antigens. This experimental procedure resulted in a generation of sperm autoantibodies cross-reactive with human, rabbit and rat spermatozoa, as demonstrated by sperm-agglutination, ELISA and flow cytometry (FCM). No specific binding to human seminal plasma was detected by ELISA, indicating that intrinsic sperm membrane antigens rather than sperm-coating antigens were involved in establishing cross-reactivity with human spermatozoa. This suggestion was confirmed by the finding that rabbit autoantisera reacted more strongly against epididymal than against ejaculated human spermatozoa as shown by FCM. Humoral antispermatozoal response correlated well with impaired spermatogenesis in rabbits. The autoimmunized rats revealed severe alterations in reproductive tissues, including testicular and epididymal sperm granulomas; however, they showed a lower incidence of circulating antibodies. The results indicate that the established experimental model in rabbits can be further used to identify and characterize evolutionary preserved intrinsic sperm membrane autoantigens, which are desirable candidates for contraceptive vaccine development.     

Microbial biogeography through the lens of exotic species: the recent introduction and spread of the freshwater diatom Discostella asterocostata in the United States

Biological Invasions - The large population sizes and high dispersal potential of microbes suggests that a given microbial species should be found in all suitable habitats worldwide. Consequently,...     

Diatoms diversify and turn over faster in freshwater than marine environments*

Many clades that span the marine–freshwater boundary are disproportionately more diverse in the younger, shorter lived, and scarcer freshwater environments than they are in the marine realm. This disparity is thought to be related to differences in diversification rates between marine and freshwater lineages. However, marine and freshwaters are not ecologically homogeneous, so the study of diversification across the salinity divide should also account for other potentially interacting variables. In diatoms, freshwater and substrate‐associated (benthic) lineages are several‐fold more diverse than their marine and suspended (planktonic) counterparts. These imbalances provide an excellent system to understand whether these variables interact with diversification. Using multistate hidden‐state speciation and extinction models, we found that freshwater lineages diversify faster than marine lineages regardless of whether they inhabit the plankton or the benthos. Freshwater lineages also had higher turnover rates (speciation + extinction), suggesting that habitat transitions impact speciation and extinction rates jointly. The plankton–benthos contrast was also consistent with state‐dependent diversification, but with modest differences in diversification and turnover rates. Asymmetric and bidirectional transitions rejected hypotheses about the plankton and freshwaters as absorbing, inescapable habitats. Our results further suggest that the high turnover rate of freshwater diatoms is related to high turnover of freshwater systems themselves.     

BioText Search Engine: beyond abstract search

The BioText Search Engine is a freely available Web-based application that provides biologists with new ways to access the scientific literature. One novel feature is the ability to search and browse article figures and their captions. A grid view juxtaposes many different figures associated with the same keywords, providing new insight into the literature. An abstract/title search and list view shows at a glance many of the figures associated with each article. The interface is carefully designed according to usability principles and techniques. The search engine is a work in progress, and more functionality will be added over time. Availability: http://biosearch.berkeley.edu.     

Glossomyophorus costatus nov. gen. nov. sp., Rudiste (Caprotinidae) nouveau de l'Aptien du domaine méditerranéen central et oriental

A new caprotinid rudist, Glossomyophorus costatus nov. gen. nov. sp. is described and figured from the Lower Cretaceous of Saudi Arabia, Bosnia (Yugoslavia) and southern Italy. Its costulate shell has a straight, tubular (attached) right valve, with a single, central tooth, and an openly enrolled, elongate left valve, with two subequal teeth. It differs from other caprotinids in possessing an erect, tongue-shaped posterior myophore in the left valve, the muscle scar of which directly flanks the body cavity, with no intervening accessory cavity joined to the central tooth socket. This scar faces onto the posterior wall of a laminar posterior myophore in the right valve. A single accessory cavity in each valve separates the posterior myophore from the shell wall. That in the right valve is similar in size to the teeth sockets, such that sections across the valve have a distinctive array of three more or less equal sockets. Evolutionary affinities with Monopleura or with Caprotina are equally possible. At present the genus is only known from the Lower Aptian of the Central and Eastern mediterranean Subprovinces and thus might serve as a valuable biostratigraphic and palaeobiogeographic marker.