Form variation and productivity of an intertidal foliose Gigartina species (Rhodophyta) in relation to wave exposure

Alona alsafadii n. sp. is described from the groundwater of river gravels in the Wadi Surdud, Yemen. It presents many characters of A. karua, but has lost its eye, has a somewhat reduced ocellus, valves which lack the fine striations between the main striae, a smallest basal spine of the postabdomen composed of c. 6 incompletely fused pectinal spinules, and some minute differences in the fine structure of the trunk limbs. It is argued that A. alsafadii has preserved some primitive characters, which throw a new light on the origin of the basal spine of the postabdomen and of the spines along the lower posterior corner of the valves.     

A sub-division ofSalmonella typhimurium into phage types based on the method of craigie and yen; Phages adaptable to species of the B and D group ofSalmonella; Phase adsorption as diagnostic aid

Summary and conclusions Phages were isolated which were adsorbed bySalmonella strains of groups B and D. These phages were adaptable to strains of species from these groups. The behaviour of some adaptations of these phages on strains ofS. paratyphi B has been described. A typing scheme forS. typhimurium has been established. So far, this consists of 32 types which have all been demonstrated with adaptations of a single phage.     

Analysis of the DNA region mediating increased thermotolerance at 58°C in <Emphasis Type="Italic">Cronobacter</Emphasis> sp. and other enterobacterial strains

Cronobacter spp. are opportunistic pathogens associated with serious infections in neonates. The increased stress tolerance, including thermoresistance, of some Cronobacter strains can promote their survival in production facilities and thus raise the possibility of contamination of dried infant milk formula, which has been identified as a potential source of infection. In this study, we characterized a DNA region which is present in some Cronobacter strains and which contributes to their prolonged survival at 58°C. The 18 kbp long region containing 22 open reading frames was sequenced in Cronobacter sakazakii ATCC 29544. The major feature of the region contained a cluster of conserved genes, most of them having significant homologies with bacterial proteins involved in some type of stress response, including heat, oxidation and acid stress. The same thermoresistance DNA region was detected in strains belonging to the genera Cronobacter, Enterobacter, Citrobacter and Escherichia and its presence positively correlated with increased thermotolerance.     

Ultrastructural features of oogenesis in some marine neoophoran turbellarians

An ultrastructural study of oogenesis has been undertaken in some marine species of neoophoran turbellarians belonging to the Tricladida, Proseriata, and Prolecithophora. Among marine triclads, Cercyra hastata has oocytes with a remarkable amount of what appears to be autosynthetic proteinaceous yolk, while Procerodes dohrni and P. lobata have alecithal oocytes. Among the Proseriata, several species of the primitive family Monocelididae (subfamily Monocelidinae) have oocytes with a discrete amount of what appears to be autosynthetic yolk, while Parotoplana macrostyla, of the derived family Otoplanidae, has alecithal eggs. Finally preliminary observations on Plagiostomum maculatum (order Prolecithophora) suggest that oocytes have autosynthetic yolk globules.These results support the hypothesis (previously formulated on the basis of similar ultrastructural investigations on freshwater triclads) that the presence of autosynthetic yolk in some neoophoran turbellarians can be interpreted as a primitive character inherited from an ancestor with archoophoran organization. This plesiomorphic character would still be maintained in some species while lost in others following differentiation of vitellaria which are characteristic of the Neoophora.     

Broomrape (Orobanche) seed germination inhibitors from plant roots

Two species (tomato and cucumber) which are not hosts to Orobanche crenata but which are hosts to other species of Orobanche not only failed to produce the compound required to trigger O. crenata to germinate but produced germination inhibitors which stopped germination even in the presence of a suitable stimulant. This suggested the possibility of using germination inhibitors to control at least some species of Orobanche. The question whether host species produce inhibitors as well as stimulants has not however been resolved.     

Rhamnolipids produced by Pseudomonas: from molecular genetics to the market

Rhamnolipids are biosurfactants with a wide range of industrial applications that entered into the market a decade ago. They are naturally produced by Pseudomonas aeruginosa and some Burkholderia species. Occasionally, some strains of different bacterial species, like Pseudomonas chlororaphis NRRL B-30761, which have acquired RL-producing ability by horizontal gene transfer, have been described. P. aeruginosa, the ubiquitous opportunistic pathogenic bacterium, is the best rhamnolipids producer, but Pseudomonas putida has been used as heterologous host for the production of this biosurfactant with relatively good yields. The molecular genetics of rhamnolipids production by P. aeruginosa has been widely studied not only due to the interest in developing overproducing strains, but because it is coordinately regulated with the expression of different virulence-related traits by the quorum-sensing response. Here, we highlight how the research of the molecular mechanisms involved in rhamnolipid production have impacted the development of strains that are suitable for industrial production of this biosurfactant, as well as some perspectives to improve these industrial useful strains.     

Applications of the aquatic higher plant Lemna gibba for ecotoxicological assessment

Although higher plants represent a significant portion of the total biomass in some aquatic environments, their use in ecosystem evaluation has lagged behind that of other organisms. This is partly due to a lack of convenient aquatic higher plant systems that can be employed for ecotoxicological assessment. However, the aquatic C-3 monocot Lemna gibba has many attributes that makes it useful for ecosystem health assessment. In this report, using examples from the literature and our research, some of the applications Lemna has for environmental research are discussed. Toxicant impacts on Lemna can be readily assessed in terms of growth; the plants multiply quickly and changes in biomass (which doubles approximately every 2 days) can be accurately measured by counting leaves. The plants are small, allowing for simultaneous multiple replication. The small size also makes the lighting conditions easy to control; sunlight can be accurately simulated and specific spectral regions can be enhanced or deleted. Lemna is amenable to in vitro chlorophyll and photosynthesis assays, which make excellent companion endpoints for growth. The plants assimilate chemicals directly from the growth medium, facilitating controlled toxicant application. Furthermore, Lemna has a high bioconcentration capacity, indicating a potential for use in bioremediation technologies.     

Toxic and repulsive effects of spray, ‘per os’ and systemic applications of destruxin E to aphids

Repellent, aphicidal, destruxin E has interesting properties towards aphids for which some important differences of susceptibility between species have been observed. M. persicae is sensitive to this molecule which kills 50% of the individuals stinging a leaf on which destruxin has been deposited at the rate of 0.4 g/cm². Feeding by the cabbage aphid, B. brassicae, is decreased by 8.8 ppm of destruxin E in the sap, whereas R. padi is resistant to inhibition of feeding activity.     

Karyological and molecular characterisation of subgenus Vicia (Fabaceae)

In the present report, we have analysed the subgenus Vicia by karyological and molecular approaches with the aim to clarify the relationships among Vicia species included in this subgenus by previously evidenced morphological investigations. Multivariate analysis using several karyomorphological parameters in addition to symmetry indices has allowed the construction of a dendrogram of linkage distances very useful to compare and to include in a phylogenetic tree obtained by internal transcribed spacer (ITS) rDNA sequences. Moreover, a separate analysis was performed combining our molecular data on ITS sequences with those reported in the literature for the section Vicilla. Our analyses partly confirm the monophyletic status of the various sections in which the subgenus Vicia has been divided, however questioning, in some cases, the real need to maintain all the nine sections so far accepted and the placement of some individual species in the two subgenera Vicia and Vicilla.     

Measurement of the adhesion of a desmid to a substrate

The paper describes a hydrodynamic method by which the adhesive strength of the mucilage produced from the apical proes of Closterium acerosum has been measured. An equation used to determine the drag force on the cells is presented, as are some measured adhesive strengths of the Closterium mucus to glass slides.     

Expression of ovule and integument‐associated genes in reduced ovules of Santalales

SUMMARY Santalales comprise mainly parasitic plants including mistletoes and sandalwoods. Bitegmic ovules similar to those found in most other angiosperms are seen in many members of the order, but other members exhibit evolutionary reductions to the unitegmic and ategmic conditions. In some mistletoes, extreme reduction has resulted in the absence of emergent ovules such that embryo sacs appear to remain embedded in placental tissues. Three santalalean representatives (Comandra, Santalum, and Phoradendron), displaying unitegmic, and ategmic ovules, were studied. Observed ovule morphologies were consistent with published reports, including Phoradendron serotinum, which we interpret as having reduced ategmic ovules, consistent with earlier reports on this species. For further understanding of the nature of the ovule reductions we isolated orthologs of the Arabidopsis genes AINTEGUMENTA (ANT) and BELL1 (BEL1), which are associated with ovule development in this species. We observed ovular expression of ANT and BEL1 in patterns largely resembling those seen in the integumented ovules of Arabidopsis. These genes were found to be expressed in the integument of unitegmic ovules and in the surface layers of ategmic ovules, and in some cases, expression of BEL1 was also observed in the surrounding carpel tissue. We hypothesize that ategmic ovules derive from a fusion of the integuments with the nucellus or that the nucellus has taken on some of the characteristics confined to integuments in ancestral species.     

Morphology,taxonomy, ecology,and distribution of <Emphasis Type="Italic">Cyclotella choctawhatcheeana</Emphasis> prasad (Bacillariophyta)

A study of the widespread centric diatom Cyclotella choctawhatcheeana has revealed the variability of qualitative and quantitative morphological diagnostic features, as well as the presence of initial cells, and allowed us to obtain new data on the ecology and distribution of the species. On the basis of original and literature data, the diagnosis of the species is emended. The conspecificity of C. tuberculata, which is common for waterbodies of the former Soviet Union, with C. choctawhatcheeana, which is new for the flora of Russia, is confirmed, making it possible to bring the first species into the synonymy of the latter. The study of samples of C. caspia from the Caspian Sea which are similar in morphology and ecology allowed us to define the variability of some features of this species and its relationship with C. choctawhatcheeana and to evaluate its taxonomical importance for some of them.     

Semi-anaerobic Growth Conditions are Favoured by some Escherichia coli Strains During Heterologous Expression of Some Archaeal Proteins

Host cell physiology is known to play a crucial role in the expression of foreign genes in heterologous systems. Expression of archaeal genes in anaerobic or semi-anaerobic growth conditions of E. coli has been previously reported to be a means of improving solubility of some proteins. Here, we report that some of the Rosetta strains of E. coli, which harbour the rare tRNA genes for the expression of archaeal genes, favour semi-anaerobic conditions for the expression of putative FMN binding domain of glutamate synthase from Methanocaldococcus jannaschii at low inducer concentrations.     

Phylogenomics with incomplete taxon coverage: the limits to inference

Background  

Phylogenomic studies based on multi-locus sequence data sets are usually characterized by partial taxon coverage, in which sequences for some loci are missing for some taxa. The impact of missing data has been widely studied in phylogenetics, but it has proven difficult to distinguish effects due to error in tree reconstruction from effects due to missing data per se. We approach this problem using a explicitly phylogenomic criterion of success, decisiveness, which refers to whether the pattern of taxon coverage allows for uniquely defining a single tree for all taxa.     

The role of glyceraldehyde 3-phosphate dehydrogenase (GapA-1) in <Emphasis Type="Italic">Neisseria meningitidis</Emphasis> adherence to human cells

Background  

Glyceraldehyde 3-phosphate dehydrogenases (GAPDHs) are cytoplasmic glycolytic enzymes, which although lacking identifiable secretion signals, have also been found localized to the surface of several bacteria (and some eukaryotic organisms); where in some cases they have been shown to contribute to the colonization and invasion of host tissues. Neisseria meningitidis is an obligate human nasopharyngeal commensal which can cause life-threatening infections including septicaemia and meningitis. N. meningitidis has two genes, gapA-1 and gapA-2, encoding GAPDH enzymes. GapA-1 has previously been shown to be up-regulated on bacterial contact with host epithelial cells and is accessible to antibodies on the surface of capsule-permeabilized meningococcal cells. The aims of this study were: 1) to determine whether GapA-1 was expressed across different strains of N. meningitidis; 2) to determine whether GapA-1 surface accessibility to antibodies was dependant on the presence of capsule; 3) to determine whether GapA-1 can influence the interaction of meningococci and host cells, particularly in the key stages of adhesion and invasion.     

Ebola and Marburg virus diseases in Africa: Increased risk of outbreaks in previously unaffected areas?

Filoviral hemorrhagic fever (FHF) is caused by ebolaviruses and marburgviruses, which both belong to the family Filoviridae. Egyptian fruit bats (Rousettus aegyptiacus) are the most likely natural reservoir for marburgviruses and entry into caves and mines that they stay in has often been associated with outbreaks of MVD. On the other hand, the natural reservoir for ebola viruses remains elusive; however, handling of wild animal carcasses has been associated with some outbreaks of EVD. In the last two decades, there has been an increase in the incidence of FHF outbreaks in Africa, some being caused by a newly found virus and some occurring in previously unaffected areas such as Guinea, Liberia and Sierra Leone, in which the most recent EVD outbreak occurred in 2014. Indeed, the predicted geographic distribution of filoviruses and their potential reservoirs in Africa includes many countries in which FHF has not been reported. To minimize the risk of virus dissemination in previously unaffected areas, there is a need for increased investment in health infrastructure in African countries, policies to facilitate collaboration between health authorities from different countries, implementation of outbreak control measures by relevant multi‐disciplinary teams and education of the populations at risk.     

Evolutionary implications of herbivory onVernonia (Compositae)

A field insect feeding experiment was conducted with two species ofVernonia which produce the sesquiterpene lactone glaucolide-A, one species which does not contain this bitter compound, and two F₁ hybrid combinations. Also, naturalVernonia populations were observed over a two year period for their degree of herbivory. Contrary to the pattern observed in laboratory feeding preference tests,Vernonia flaccidifolia, the species lacking sesquiterpene lactones, was consistently fed upon less by insects than wereV. gigantea andV. glauca. Even though glaucolide-A appears to adequately protect some Vernonias against herbivores, especially mammals,Vernonia flaccidifolia has lost this compound. ApparentlyV. flaccidifolia has evolved an alternative defensive mechanism which is more effective against insects but less effective against mammalian herbivores.     

Listeria monocytogenes,a model in infection biology

Listeria monocytogenes causes listeriosis, a systemic infection which manifests as bacteremia, often complicated by meningoencephalitis in immunocompromised individuals and the elderly, and fetal‐placental infection in pregnant women. It has emerged over the past decades as a major foodborne pathogen, responsible for numerous outbreaks in Western countries, and more recently in Africa. L. monocytogenes' pathogenic properties have been studied in detail, thanks to concomitant advances in biological sciences, in particular molecular biology, cell biology and immunology. L. monocytogenes has also been instrumental to basic advances in life sciences. L. monocytogenes therefore stands both a tool to understand biology and a model in infection biology. This review briefly summarises the clinical and some of the pathophysiological features of listeriosis. In the context of this special issue, it highlights some of the major discoveries made by Pascale Cossart in the fields of molecular and cellular microbiology since the mid‐eighties regarding the identification and characterisation of multiple bacterial and host factors critical to L. monocytogenes pathogenicity. It also briefly summarises some of the key findings from our laboratory on this topic over the past years.     

Molecular data reveal a diverse Astyanax species complex in the upper Iguaçu River

Astyanax is among the most speciose genera in the Characidae. In this study, molecular markers were used to assess the extent to which some of the commonly recognized Astyanax species of the upper Iguaçu River correspond to natural groups. These results indicate that the diversity of Astyanax has been severely underestimated with several potential cryptic species.