Fouling of ceramic membranes during microfiltration of model solutions

A model study of the microfiltration of fatty acids (C2 to C8) dissolved in a synthetic ultrafiltrate was performed. Ceramic membranes of 0.1 and 0.2 m were used. Results showed that minerals from the ultrafiltrate were involved in membrane fouling, while fatty acids were poorly rejected.On 0.1 m membranes, modelisation of fouling exhibited two different steps of fouling, a first one due to adsorption of solutes, and a second one involving particles deposit onto the membrane. On 0.2 m membranes, only fouling due to particles deposit was observed in modelisation. Results of fouling and rejection pointed out the great difference between 0.1 and0.2 m membranes.This revised version was published online in October 2005 with corrections to the Cover Date.     

Geometric preferences of crosslinked protein-derived cofactors reveal a high propensity for near-sequence pairs

Protein-derived cofactors that are composed of covalently crosslinked amino acid side chains are of increasing importance in protein science. These crosslinked protein-derived cofactors (CPDC) are formed either through direct oxidation by metal/O(2)-derived intermediates or through outer sphere oxidation by highly oxidizing cofactors. CPDCs that are formed by outer sphere oxidation do not require side-chain precursors to be coordinated by a metal center, and therefore are more difficult to identify than those formed by direct oxidation. To better understand the propensity for CPDC formation by outer sphere oxidation, the geometrical preferences of CPDCs were examined. The Dezymer algorithm has been used to identify all putative CPDC-forming mutations in 500 proteins. Geometrically, although chemically unrelated, these CPDCs were found to be similar to disulfide-bonded cysteine pairs. Additionally, the percentage of near-sequence pairs (i and i +1 to i and i + 5) increased as the average C(alpha)-C(alpha) distance between the amino acid pairs increased. This survey also examined the protein databank for proteins with pre-attack conformations for CPDCs, using non-bonded contacts reported by Procheck. A total of 323 unique proteins was identified, with 55 being near-sequence amino acid pairs. The high geometric propensity of near-sequence amino acid pairs for forming CPDCs is significant due to difficulties associated with detection by structural or mass spectrometric methods.     

Polymorphic tetranucleotide microsatellites for Cope's giant salamander (Dicamptodon copei) and Pacific giant salamander (Dicamptodon tenebrosus)

We present primers and amplification conditions for 15 microsatellite loci developed for the Cope's giant salamander (Dicamptodon copei), 14 of which are tetranucleotide repeats. Cross-species amplification revealed 10 of these loci to also be polymorphic in the Pacific giant salamander (Dicamptodon tenebrosus). Several loci produced nonoverlapping allelic ranges between the two species and may be useful in species identification. These polymorphic microsatellite loci are potentially useful for future studies of population genetics in dicamptodontid salamanders.     

Effects of pollen donors on seed formation inEspeletia schultzii (Compositae) populations at different altitudes

The influence of different pollen donors on seed formation was investigated in three populations ofEspeletia schultzii that differ in environmental conditions and life history characteristics. Self pollen and pollen from different donors (< 15m apart) within each population was used in a diallel design in order to test the genetic base of seed set variation. Three measures of seed formation were used: (1) achene number; (2) proportion of filled achenes (fruits) that distinguishes between achenes with seeds and empty achenes; (3) proportion of aborted seeds that distinguishes between viable and aborted seeds. Self-pollinations resulted in empty achenes. Achene number did not vary between the different pollen donors. A bimodal pattern of filled achenes was found in two populations in two consecutive years. On the other hand, a unimodal pattern was found in crosses between more distant donors (> 30m). These patterns seems to be the results of a sporophytic incompatibility system. Seed abortion was highest at the higher elevations and seems to be correlated with elevation rather than with any genetic effect.     

Variation in mate recognition specificities among four Callosobruchus seed beetles

Differentiation of mate recognition systems is one of the important steps for speciation in animals. For some insects, a contact sex pheromone present on the cuticular surface is indispensable in discriminating reproductive partners. In Callosobruchus species (Coleoptera: Chrysomelidae: Bruchinae), contact sex pheromones have been found in two species, Callosobruchus chinensis (L.) and Callosobruchus maculatus (Fabricius). It was suggested, however, that these two species lacked the ability to discriminate their conspecific and/or heterosexual partners. To elucidate this inconsistency, we verified the existence of contact sex pheromones from two other species, Callosobruchus rhodesianus (Pic) and Callosobruchus analis (Fabricius). As a result, unlike C. chinensis and C. maculatus, the males of C. rhodesianus and C. analis were able to discriminate their heterosexual partners. Comparing cross‐copulation behavior, i.e., copulation behavior between two species, against these four species indicated that the mate recognition specificities were quite different. Males of C. rhodesianus and C. analis had highly species‐specific mating behavior, whereas males of C. chinensis and C. maculatus were much less specific. These results indicate that variation in mate recognition can arise even among congeneric species living in a sympatric environment, and this variation might have arisen during species differentiation. Based on our results in combination with previous reports on interspecific competition, we suggest that the observed asymmetric cross‐copulation behavior might be, at least partially, an adaptation for surviving interspecific competition.     

Development of microsatellite markers in the Japanese pear (Pyrus pyrifolia Nakai)

Thirteen polymorphic microsatellite loci were developed in the Japanese pear (Pyrus pyrifolia Nakai) by using an enriched genomic library. The obtained microsatellite loci showed a high degree of polymorphism in the Japanese pear with 3–6 alleles per locus. The average values of observed and expected heterozygosities among these 13 loci were 0.69 and 0.71, respectively. Ten microsatellites could successfully amplify loci in the European pear (Pyrus communis L.), which were highly polymorphic as well.     

Prognostic relevance of miR-137 and its liver microenvironment regulatory target gene AFM in hepatocellular carcinoma

MiR-137 has been identified as potential hepatocellular carcinoma (HCC) prognostic biomarkers. Highly relevant HCC prognostic biomarkers may be derived from combinations of miR-137 with its target genes involved in the regulation of liver microenvironment. This study aimed at the discovery of such a combination with improved HCC prognosis performance than miR-137 or its target gene alone in a significantly higher number of HCC patients than previous studies. Analysis of the differentially expressed micro RNAs (miRNAs) between cancer and noncancer tissues reconfirmed miR-137 to be among the most relevant prognostic miRNAs and the data of 375 HCC patients and 50 normal cases were from the Cancer Genome Atlas (TCGA) data sets. Target genes were identified by the established search methods and Kaplan–Meier survival analysis of HCC patients was used to evaluate the overall survival (OS) and recurrence-free survival (RFS). Cox proportional hazards regression indicated that the miR-137 and its target gene AFM combination is an independent prognostic factor for the OS and RFS in HCC. In vitro experiments validated that miR-137 could bind to 3′-untranslated region of the AFM and promote the invasion and metastasis of HCC cell lines. The expressions of miR-137 and its liver microenvironment regulatory target gene AFM in combination significantly correlated with HCC progression in a higher number of patients than in previous studies, which suggested their potential as prognostic biomarkers for HCC.     

Perspectives of gene combinations in phenotype presentation

Cells exhibit a variety of phenotypes in different stages and diseases. Although several markers for cellular phenotypes have been identified, gene combinations denoting cellular phenotypes have not been completely elucidated. Recent advances in gene analysis have revealed that various gene expression patterns are observed in each cell species and status. In this review, the perspectives of gene combinations in cellular phenotype presentation are discussed. Gene expression profiles change during cellular processes, such as cell proliferation, cell differentiation, and cell death. In addition, epigenetic regulation increases the complexity of the gene expression profile. The role of gene combinations and panels of gene combinations in each cellular condition are also discussed.     

Genetic structure and host–parasite co‐divergence: evidence for trait‐specific local adaptation

Host–parasite co‐evolution can lead to genetic differentiation among isolated host–parasite populations and local adaptation between parasites and their hosts. However, tests of local adaptation rarely consider multiple fitness‐related traits although focus on a single component of fitness can be misleading. Here, we concomitantly examined genetic structure and co‐divergence patterns of the trematode Coitocaecum parvum and its crustacean host Paracalliope fluviatilis among isolated populations using the mitochondrial cytochrome oxidase I gene (COI). We then performed experimental cross‐infections between two genetically divergent host–parasite populations. Both hosts and parasites displayed genetic differentiation among populations, although genetic structure was less pronounced in the parasite. Data also supported a co‐divergence scenario between C. parvum and P. fluviatilis potentially related to local co‐adaptation. Results from cross‐infections indicated that some parasite lineages seemed to be locally adapted to their sympatric (home) hosts in which they achieved higher infection and survival rates than in allopatric (away) amphipods. However, local, intrinsic host and parasite characteristics (host behavioural or immunological resistance to infections, parasite infectivity or growth rate) also influenced patterns of host–parasite interactions. For example, overall host vulnerability to C. parvum varied between populations, regardless of parasite origin (local vs. foreign), potentially swamping apparent local co‐adaptation effects. Furthermore, local adaptation effects seemed trait specific; different components of parasite fitness (infection and survival rates, growth) responded differently to cross‐infections. Overall, data show that genetic differentiation is not inevitably coupled with local adaptation, and that the latter must be interpreted with caution in a multi‐trait context.