Developments in the understanding of the biology of marine wood boring crustaceans and in methods of controlling them

The most economically important wood boring Crustacea belong to the isopod families Sphaeromatidae and Limnoriidae, both of which have been recently revised and a number of new species have been recognised. Other wood boring crustaceans have now been recognised from tropical mangrove sites. Limnoriids are found from temperate to tropical waters, but appear to be restricted to waters with salinities close to that of seawater. Wood-boring species of Sphaeroma on the other hand can tolerate extremely low salinities, but are restricted to sub-tropical and tropical waters. Approaches to borer control that have proved effective against teredinids (use of naturally durable timber, copper-chrome-arsenic or creosote treatment, surface coatings) have been found under certain circumstances to be ineffective against Limnoria and Sphaeroma. A number of additives to conventional preservatives have been tested, with some insecticides showing evidence of enhancing Limnoria control. The question of crustacean borer nutrition may hold the key to problems of their control. Sphaeromatid borers are capable of filter-feeding and thus may never ingest the treatments applied to wood. Limnoriids do ingest wood, but the role of wood degrading tunneling bacteria, and soft-rotting ascomycete and deuteromycete fungi occurring in the wood they digest remains to be fully elucidated. The source or sources of wood-degrading enzymes that permit digestion of wood particles requires further investigation. The microecology of borer burrows has an important bearing on the availability of nitrogen for borers. Further insights into the problems posed by these borers may be obtained with a better understanding of their ecology. A better testing protocol for preservatives has been developed as a result of knowledge of the natural vertical distribution of Sphaeroma. Behavioural studies indicate that settlement on wood by Limnoria is enhanced by factors derived from conspecifics and from wood-inhabiting microorganisms.     

The diversity of Pityrosporum (Malassezia) yeasts in vivo and in vitro

Conclusions In considering the diversity of the lipophilic yeasts it has been shown that in vivo both spherical and oval yeasts may be found in normal conditions on the skin and also associated with hyphae in scales from pityriasis versicolor. There is however generally a different distribution pattern on the body for two forms. This may indicate a different ecology for two distinct varieties or the varying conditions at each site may influence changes in the cell shape of a single species. It is striking that the spherical yeasts (P. orbiculare) have not been found in animals. In vitro, several morphological variants can be maintained, but the change from one form to another which is the subject of a number of reports will be one deciding factor leading to the opinion that P. orbiculare and P. ovale are synonymous. However, physiological differences such as growth rate, their viability in subculture and the analysis of proteins, are all characteristics which alone would be insufficient to support a taxonomic division but when added together confirm the morphological separation of isolates. It remains to be seen if DNA studies, which have so far unified the anthropophilic, lipid dependant Pityrosporum yeasts, will in fact continue to show that they should be confined to a single species.This paper was presented at the X^th congress of the International Society for Human and Animal Mycology at Barcelona, Spain from June 27 to July 1, 1988.     

Developmental puffing patterns in salivary gland chromosomes of Rhynchosciara hollaenderi

An analysis of puff formation and regression has been carried out in 3 morphologically distinct regions of the Rhynchosciara hollaenderi salivary gland during mid-larval through pupal development. Puffing differences among these 3 regions have been found and analysed for both RNA and DNA puffs. The presence of such differences suggests that the gland regions may also be functionally differentiated. — Developmentally specific sequences of puffs have been distinguished and correlated with morphological and physiological events which occur during the development of Rhynchosciara. The DNA puffs as well as the RNA puffs enlarge and regress at predictably specific developmental stages. The presence of particular puffing sequences in the late larval to pupal period has been compared with the occurrence of known changes in the developmental ecdysone titre for Rhynchosciara. Certain aspects of this developmental picture appear to fit the ecdysone-stimulated puffing model for Drosophila, but other aspects indicate that the Drosophila-based model may not be completely applicable to Rhynchosciara.     

Mechanisms involved in the neurotoxic effects of environmental toxicants such as polychlorinated biphenyls and brominated flame retardants

Many toxic substances have been distributed to the environment, some of which have properties that promote accumulation and biomagnification in living organisms. Approximately 1.2 million metric tons of polychlorinated biphenyls (PCBs) have been produced and about 30% have been discharged to the environment. Approximately 200 000 metric tons of brominated flame retardants (BFRs) are produced annually, of which considerable amounts have been spread globally, even to the Polar Regions. Behavioral testing of animals has shown that these compounds may affect learning, memory and fine motor functions. Animals are most sensitive during early development. Several epidemiological studies have shown that PCBs and BFRs may be responsible for similar effects in humans. Of especially concern are possible effects of PCBs and BFRs in mixtures containing the highly neurotoxic methyl mercury. The compounds affect several targets in the nervous system that seem to be interconnected, and may be responsible for the observed behavioral deficits. It was shown early that PCBs affect dopamine and serotonin levels in the brain. Later studies showed that transport mechanisms of these neurotransmitters appear to be particularly sensitive to PCBs. Furthermore, PCBs affect intracellular calcium levels and induce formation of reactive oxygen species both in vivo and in vitro, and reduce cell viability in vitro. Neuroendocrine functions, particularly the thyroid hormone system, are also sensitive to disruption by PCBs and BFRs. Their metabolites, such as hydroxy‐metabolites, appear to be particularly potent. We conclude that PCBs are particularly toxic during early development and that the toxic effects are a combination of several factors, including disturbance of calcium homeostasis, oxidative stress, and influence on neurotransmitter transport. Monoaminergic cells appear to be particularly vulnerable.     

A possible hot spot for Ac insertion in the maize P gene.

Summary We have analyzed the footprints left by a single Ac transposable element during its intragenic transposition to different positions in the maize P gene. One site appears to have been visited twice by transposons, indicating that it may be an insertion hot spot. Implications of this finding for the origin of the P-vv allele are discussed. Analysis of transposon footprints may prove generally useful for establishing pedigree relationships among gene alleles.     

Bakterien,die in Acanthamöben leben: Dasein im Verborgenen

One fourth of Acanthamoebaisolates studied contain obligate bacterial endosymbionts. These intracellular bacteria have recently been assigned to four different, previously unknown phylogenetic lineages within the Proteobacteriaand the Chlamydiales. The symbiotic association of these amoebae and their bacterial endosymbionts might be a valuable model system for the analysis of bacterial adaptations and mechanisms for intracellular survival. In addition, Chlamydia‐related amoebal endosymbionts have been implicated as causative agents for respiratory disease suggesting that these protozoa may be sources of new emerging pathogens.     

Genetic differentiation,polyploidization and hybridization in northern EuropeanDactylorhiza (Orchidaceae): Evidence from allozyme markers

Taxa endemic to North-western Europe are rare, but the orchid genusDactylorhiza contains several species restricted to this area. Evidence from morphological and cytological studies have indicated that some species may have arisen recently and may be of hybrid origin. In the present report, I use allozymes to characterize the genomes in various species ofDactylorhiza and evaluate the possibilities for rapid evolutionary change in the genus. Allotetraploid species have evolved repeatedly from two principal diploid ancestral lineages. These lineages include extant diploid and autotetraploid species, from which allotetraploid derivatives may still arise. It is suggested that allotetraploidization dominates over introgression as speciation mechanism in the genus. The more common and widespread allotetraploid species could be characterized by their allozyme characters over considerable distances, indicating that each of them may have a unique origin and that they have spread from their ancestral populations to the present distribution areas. However, it is also possible that some allotetraploid species contain local populations that have been independently derived from the ancestral lineages.     

Heat Stress-Induced Life Span Extension in Yeast

The yeastSaccharomyces cerevisiaehas a limited life span that can be measured by the number of times individual cells divide. Several genetic manipulations have been shown to prolong the yeast life span. However, environmental effects that extend longevity have been largely ignored. We have found that mild, nonlethal heat stress extended yeast life span when it was administered transiently early in life. The increased longevity was due to a reduction in the mortality rate that persisted over many cell divisions (generations) but was not permanent. The genesRAS1andRAS2were necessary to observe this effect of heat stress. TheRAS2gene is consistently required for maintenance of life span when heat stress is chronic or in its extension when heat stress is transient or absent altogether.RAS1,on the other hand, appears to have a role in signaling life extension induced by transient, mild heat stress, which is distinct from its life-span-curtailing effect in the absence of stress and its lack of involvement in the response to chronic heat stress. This distinction between theRASgenes may be partially related to their different effects on growth-promoting genes and stress-responsive genes. Theras2mutation clearly hindered resumption of growth and recovery from stress, while theras1mutation did not. TheHSP104gene, which is largely responsible for induced thermotolerance in yeast, was necessary for life extension induced by transient heat stress. An interaction between mitochondrial petite mutations and heat stress was found, suggesting that mitochondria may be necessary for life extension by transient heat stress. The results raise the possibility that theRASgenes and mitochondria may play a role in the epigenetic inheritance of reduced mortality rate afforded by transient, mild heat stress.     

Superhelix density heterogeneity in closed circular intracellular PM2 DNA

Covalently closed intracellular DNA obtained from Pseudomonas BAL 31 20 min after infection with PM2 phage has been shown to be heterogeneous in superhelix density. Analytical band sedimentation, in the presence of low concentrations of ethidium bromide, has been carried out on fractions centripetal and centrifugal to the mode of a single band of closed circular DNA in a preparative propidium iodide–CsCl buoyant density gradient. Different average sedimentation rates, as well as different band shapes, have been observed for upper and lower fractions centrifuged at a dye concentration near the minimum in s° versus ethidium bromide concentration titrations performed on DNA from proximate intermediate fractions. Similar differences, although not as pronounced, have been obtained at a dye concentration corresponding to a point in the steep region of the titrations. Differential band sedimentation experiments performed on the same fractions have confirmed these results. Differential band sedimentation experiments on similarly fractionated mature PM2 I DNA (closed circular form) have shown slight differences in the relative sedimentation rates of upper and lower fractions at dye concentrations corresponding to the steep regions in the titrations. The same experiments, when performed on nicked circular DNA obtained from heating both the mature and intracellular fractions, showed no evidence of differences in sedimentation coefficients. Such results may indicate slight heterogeneity in the superhelix density of viral PM2 I DNA; however, the degree of this heterogeneity would be somewhat less than that of the intracellular DNA. The possibility that superhelix density heterogeneity may arise from displacement loops, which have been found at low levels in intracellular PM2 DNA, has been subjected to experimental tests. Unless such structures are originally present and removed by the isolation procedure, this possibility may be rejected.     

Specific substrates for isolation and differentiation of Azotobacter vinelandii

Summary Resorcinol, ethylene glycol and glutaric acid have been found to be specific substrates for the enrichment of Azotobacter vinelandii in the presence of other Azotobacter species. The three compounds may also be used for species differentiation in the genus Azotobacter. In contrast to other reports strains of A. chroococcum and A. beijerinckii have been isolated which are able to use L-rhamnose for growth.Conditions for the production of a yellow pigment and green fluorescence by A. vinelandii from non-aromatic substrates on agar-plates have been tested.The production of water soluble yellow pigments in benzoate containing media cannot be used as a criterium for the presence of A. vinelandii. The pigment seems to be -hydroxy-muconic semialdehyde, the splitting product resulting from metacleavage of catechol. It may be formed by all Azotobacter species that can metabolize aromatic substrates.     

中国菊科一新归化植物——白花金钮扣

报道了中国菊科一新归化植物——白花金钮扣[Acmella radicans var. debilis (Kunth) R. K. Jansen],并提供了该变种详细的特征描述和彩色照片。该变种原产南美洲和西印度群岛,最近在我国安徽黟县发现一归化居群。野外调查发现,该植物在黟县生长旺盛,成熟时种子结实量大,表现出一定的入侵性。     

Extended glycan diversity in a bacterial protein glycosylation system linked to allelic polymorphisms and minimal genetic alterations in a glycosyltransferase gene

Glycans manifest in conjunction with the broad spectrum O‐linked protein glycosylation in species within the genus Neisseria display intra‐ and interstrain diversity. Variability in glycan structure and antigenicity are attributable to differences in the content and expression status of glycan synthesis genes. Given the high degree of standing allelic polymorphisms in these genes, the level of glycan diversity may exceed that currently defined. Here, we identify unique protein‐associated disaccharide glycoforms that carry N‐acetylglucosamine (GlcNAc) at their non‐reducing end. This altered structure was correlated with allelic variants of pglH whose product was previously demonstrated to be responsible for the expression of glucose (Glc)‐containing disaccharides. Allele comparisons and site‐specific mutagenesis showed that the presence of a single residue, alanine at position 303 in place of a glutamine, was sufficient for GlcNAc versus Glc incorporation. Phylogenetic analyses revealed that GlcNAc‐containing disaccharides may be widely distributed within the pgl systems of Neisseria particularly in strains of N. meningitidis. Although analogous minimal structural alterations in glycosyltransferases have been documented in association with lipopolysaccharide and capsular polysaccharide variability, this appears to be the first example in which such changes have been implicated in glycan diversification within a bacterial protein glycosylation system.     

Survey and management of mussel Mytilus species in Scotland

The important ecological role of Mytilus mussels in marine ecosystems, their high abundance in coastal waters and the demand for human consumption has made them a target species for aquaculture. Mussel cultivation is the most important and rapidly growing sector of the Scottish shellfish aquaculture industry and until recently production was considered to be based exclusively on the native species Mytilus edulis. However, the sympatric occurrence of M. edulis, M. trossulus, M. galloprovincialis and their hybrids in cultivation has recently been reported and significant production losses (over 50% at some sites) have been attributed to the presence of fragile-shelled M. trossulus. Given the ecological and economical importance of these species, an urgent need arose for a wider understanding of Mytilus species distribution on Scottish coasts and its implication for the sustainability of the Scottish shellfish industry. Here we present a summary of a 3-year project established within the “ECOsystem approach to SUstainable Management of the Marine Environment and its living Resources” (ECOSUMMER) Marie Curie network to address this need. We developed DNA-based molecular assays for the detection and surveillance of the different Mytilus species in Scotland. Several potential management strategies have been explored, aimed at favouring M. edulis production at mixed-species sites, but these have so far not been found to provide the reliable efficacy necessary for adoption by the industry. Complete eradication of M. trossulus from economically affected areas in Scotland may be unrealistic, especially considering that its introduction and distribution mechanisms in the environment remain uncertain. Area-specific solutions to managing the problem may thus be required, which may or may not involve eradication and fallowing (clearance of mussels from production sites for a given period of time). Nevertheless, the current distribution of M. trossulus is limited and its spread outside its existing range is clearly undesirable. Any management solutions must also be accompanied by an industry wide strategy and awareness, for example, through the development of an industry supported code of good practice.     

Cloning and Biochemical Characterization of <Emphasis Type="Italic">ToFZY</Emphasis>, a Tomato Gene Encoding a Flavin Monooxygenase Involved in a Tryptophan-dependent Auxin Biosynthesis Pathway

Indole-3-acetic acid (IAA), the main endogenous auxin, has been known for decades to be a key regulator for plant growth and development. Multiple routes have been proposed for IAA biosynthesis but physiologic roles or relevance of the different routes are still unclear. Recently, four members of the Arabidopsis thaliana YUC gene family have been implicated in an additional requirement of IAA involved in floral organ and vascular tissue formation. The loss-of-function yuc1yuc4 double mutants in Arabidopsis displayed phenotypes similar to the previously described loss-of-function floozy mutants in petunia (fzy). Moreover, it has been demonstrated that YUC1 encodes a flavin monooxygenase (FMO) that catalyzes a rate-limiting step of a tryptophan-dependent auxin biosynthesis pathway: the conversion of tryptamine to N-hydroxyl-tryptamine. Here we report on the genetic study of ToFZY, the putative tomato ortholog of YUC4 and FZY, including gene and cDNA sequence comparison and a preliminary expression analysis. In addition, we describe a novel conserved amino acid motif that may be considered a hallmark potentially useful for the identification of new YUC-like FMOs. We also demonstrate that ToFZY encodes a protein with the same enzymatic activity as YUC1. Finally, we provide evidence suggesting that the ToFZY gene belongs to a multigenic family whose members may exhibit a temporal and spatial specialization similar to that described in A. thaliana.     

Cell culture aging

Summary Cellular research in aging has been stimulated by the observation that human diploid cells have a limited number of cell divisions in culture. This loss of cellular proliferation (in vitro senescence) has been extensively studied by biochemical, clonal, and genetic analysis. Studies of human skin fibroblast cultures have revealed thatin vitro senescense is related toin vivo human cellular aging. Recently differentiated cells have been proposed for aging studies. These cells may provide additional information on aging since alterations ofin vitro cellular functions may be related to thein vivo behavior of specific differented cell types.     

Characterization of Pisrt1/Foxl2 in Ellobius lutescens and exclusion as sex-determining genes

The rodent Ellobius lutescens is an exceptional mammal which determines male sex constitutively without the SRY gene and, therefore, may serve as an animal model for human 46,XX female-to-male sex reversal. It was suggested that other factors of the network of sex-determining genes determine maleness in these animals. However, some sex-determining genes like SOX9 and SF1 have already been excluded by segregation analysis as primary sex-determining factors in E. lutescens. In this work, we have cloned and characterized two genes of the PIS (polled intersex syndrome) gene interval, which were reported as candidates in female-to-male sex reversal in hornless goats recently. The genes Foxl2 and Pisrt1 from that interval were identified in E. lutescens DNA and mapped to Chromosome 8. We have excluded linkage of Foxl2 and Pisrt1 loci with the sex of the animals. Hence, the involvement of this gene region in sex determination may be specific for goats and is not a general mechanism of XX sex reversal or XX male sex determination.The nucleotide sequence data reported in this article have been submitted to GenBank and have been assigned the accession number AY623815.