Description of three species of Holorchis Stossich, 1901 (Digenea: Lepocreadiidae) from marine fishes off Corsica

Three species of Holorchis are redescribed from marine fishes from off Corsica. They are: Holorchis pycnoporus from Diplodus vulgaris, D. sargus, Lithognathus mormyrus, Pagellus erythrinus, Sparus pagrus and Symphodus roissali; H. micracanthum from Sparus pagrus and Pagellus erythrinus; and H. legendrei from Mullus surmuletus. The characteristics differentiating these species are discussed, in particular those separating H. pycnoporus and H. legendrei, species which previously have been considered synonyms. The internal morphology of the cirrus-sac differs distinctly between these forms, which also have microhabitat and host differences.     

Interorder transfer of mycoplasma-like microorganisms between Drosophila paulistorum and Ephestia kuehniella: Tissues,dosages, and effects

Testis and head extracts of sterile male intersemispecific hybrid Drosophila paulistorum are pathogenic when injected into Ephestia kuehniella larvae. The time and frequency of death of the recipients is a function of the extract concentration. Extracts of Ephestia recipients are pathogenic and will kill E. kuehniella larvae and D. paulistorum adults. Larval Drosophila recipients of these extracts survive through pupation. A majority of these recipients fail to eclose. Those animals which do survive to the adult stage and which are fertile demonstrate the same pattern of sterility among their progeny as is found in D. paulistorum hybrids and recipients of D. paulistorum extracts. The results indicate that the pathogenicity of the extracts is due to the mycoplasma-like microorganisms which are responsible for the male intersemispecific hybrid sterility in D. paulistorum. The mycoplasma-like microorganisms grow rapidly in E. kuehniella hosts, with a division time of approximately 1.8 hr, and they retain their host specificity for the semispecies of D. paulistorum.     

Systematics and evolution of the genus Clathrobaculus Cossmann, 1912 (Gastropoda, Mathildidae)

The morphology and ontogeny of Jurassic gastropods those have been included in the genera Clathrobaculus Cossmann, 1912 and Gordenella Gründel, 1990 are discussed. Based on the ontogenetic research of their shells, several types of ontogeny are established in the species of these genera. The suggestion is made that the genus Gordenella should be considered as a junior synonym of Clathrobaculus within the family Mathildidae. The protoconchs of Clathrobaculus species are studied to reveal their morphological variability and a number of distinguishing characters in which they differ from the protoconchs of other mathildid genera. Four species of Clathrobaculus, of which two are new (C. medidilatatus and C. inconstantiplicatus), are described from the Jurassic deposits of the European part of Russia. The composition of C. fahrenkohli (Rouillier, 1846) and C. krantzi (Rouillier, 1849) is emended, and the protoconchs of these species and of the species C. inconstantiplicatus are described for the first time.     

Conservation of gene linkage in dispersed vertebrate NK homeobox clusters

Nk homeobox genes are important regulators of many different developmental processes including muscle, heart, central nervous system and sensory organ development. They are thought to have arisen as part of the ANTP megacluster, which also gave rise to Hox and ParaHox genes, and at least some NK genes remain tightly linked in all animals examined so far. The protostome–deuterostome ancestor probably contained a cluster of nine Nk genes: (Msx)–(Nk4/tinman)–(Nk3/bagpipe)–(Lbx/ladybird)–(Tlx/c15)–(Nk7)–(Nk6/hgtx)–(Nk1/slouch)–(Nk5/Hmx). Of these genes, only NKX2.6–NKX3.1, LBX1–TLX1 and LBX2–TLX2 remain tightly linked in humans. However, it is currently unclear whether this is unique to the human genome as we do not know which of these Nk genes are clustered in other vertebrates. This makes it difficult to assess whether the remaining linkages are due to selective pressures or because chance rearrangements have “missed” certain genes. In this paper, we identify all of the paralogs of these ancestrally clustered NK genes in several distinct vertebrates. We demonstrate that tight linkages of Lbx1–Tlx1, Lbx2–Tlx2 and Nkx3.1–Nkx2.6 have been widely maintained in both the ray-finned and lobe-finned fish lineages. Moreover, the recently duplicated Hmx2–Hmx3 genes are also tightly linked. Finally, we show that Lbx1–Tlx1 and Hmx2–Hmx3 are flanked by highly conserved noncoding elements, suggesting that shared regulatory regions may have resulted in evolutionary pressure to maintain these linkages. Consistent with this, these pairs of genes have overlapping expression domains. In contrast, Lbx2–Tlx2 and Nkx3.1–Nkx2.6, which do not seem to be coexpressed, are also not associated with conserved noncoding sequences, suggesting that an alternative mechanism may be responsible for the continued clustering of these genes.     

Precise Mapping of the Homothallism Genes HML and HMR in SACCHAROMYCES CEREVISIAE

The HML and HMR loci carry unexpressed copies of MATa and MATα information, and a replica of that information is transposed to MAT during mating-type interchange in Saccharomyces yeasts. A negative control mechanism keeps silent the information located at the HML and HMR loci. We mapped these loci by constructing strains in which these loci are expressed. In these strains, the mating type of the segregants is dependent upon the allele at HML and HMR. This novel approach is independent of their switching function. HML is located on the left arm of chromosome III distal to his4 by about 26.8 centimorgans (cM). HMR maps on the right arm of the same chromosome distal to thr4 by about 39.8 cM and proximal to MAL2 by about 1.0 cM. The results allow the exact placement of these loci and are in accord with the observations made by Harashima and Oshima (1976).     

New Ordovician ostracodes from Himalaya and their palaeobiological and palaeogeographical implications

Silicified representatives of the ostracode orders Binodicopa, Palaeocopa and Podocopa have been recovered from the late Ordovician Pin Formation, Spiti, NW Himalaya area. Benthic binodicopes are distinctly more abundant than the palaeocope and podocope ostracodes. The binodicopes show biogeographical relations to Australia at the generic level, which supports the close palaeogeographic position of these continents. By contrast, the palaeocope and podocope taxa show close relations to Baltica and Bohemia even at the species level, which may suggest a pelagic or epipelagic mode of life since these regions are separated from each other by the broad and deep waters of Palaeotethys. New taxa are Vendona crassiplicata nov. sp., Glossomorphites himalayaensis nov. sp., Pilla pinensis nov. sp. and Pinpilla u-formis nov. gen. nov. sp.     

Thioredoxin can influence gene expression by affecting gyrase activity

The expression of many genes of facultatively photosynthetic bacteria of the genus Rhodobacter is controlled by the oxygen tension. Among these are the genes of the puf and puc operons, which encode proteins of the photosynthetic apparatus. Previous results revealed that thioredoxins are involved in the regulated expression of these operons, but it remained unsolved as to the mechanisms by which thioredoxins affect puf and puc expression. Here we show that reduced TrxA of Rhodobacter capsulatus and Rhodobacter sphaeroides and oxidized TrxC of R.capsulatus interact with DNA gyrase and alter its DNA supercoiling activity. While TrxA enhances supercoiling, TrxC exerts a negative effect on this activity. Furthermore, inhibition of gyrase activity strongly reduces puf and puc expression. Our results reveal a new signaling pathway by which oxygen can affect the expression of bacterial genes.     

Wound-Released Chemical Signals May Elicit Multiple Responses from an Agrobacterium tumefaciens Strain Containing an Octopine-Type Ti Plasmid

The vir regions of octopine-type and nopaline-type Ti plasmids direct the transfer of oncogenic T-DNA from Agrobacterium tumefaciens to the nuclei of host plant cells. Previous studies indicate that at least two genetic loci at the left ends of these two vir regions are sufficiently conserved to form heteroduplexes visible in the electron microscope. To initiate an investigation of these genetic loci, we determined the DNA sequences of these regions of both Ti plasmids and identified both conserved loci. One of these is the 2.5-kb virH locus, which was previously identified on the octopine-type Ti plasmid but thought to be absent from the nopaline-type Ti plasmid. The virH operon contains two genes that resemble P-450-type monooxygenases. The other locus encodes a 0.5-kb gene designated virK. In addition, we identified other potential genes in this region that are not conserved between these two plasmids. To determine (i) whether these genes are members of the vir regulon and, (ii) whether they are required for tumorigenesis, we used a genetic technique to disrupt each gene and simultaneously fuse its promoter to lacZ. Expression of these genes was also measured by nuclease S1 protection assays. virK and two nonconserved genes, designated virL and virM, were strongly induced by the vir gene inducer acetosyringone. Disruptions of virH, virK, virL, or virM did not affect tumorigenesis of Kalanchöe diagramontiana leaves or carrot disks, suggesting that they may play an entirely different role during pathogenesis.     

Genetic fusions that help define a transcription termination region in Escherichia coli

The trpA gene product was analyzed from a class of strains of Escherichia coli K12 in which the lac operon has been fused by deletion to the trp operon. These are strains that have retained the ability to synthesize tryptophan. Two of these strains are shown to make a wild-type trpA product; these strains retain intact all structural genes of the ttrp operon. It is proposed that the lac operon in these strains is fused to a region of the trp operon between trpA, the last gene in the operon, and the region where trp messenger RNA synthesis terminates. The region where trp messenger RNA synthesis terminates thus is distinct from the trp structural genes.     

Unripe red fruits may be aposematic

The unripe fruits of certain species are red. Some of these species disperse their seeds by wind (Nerium oleander, Anabasis articulata), others by adhering to animals with their spines (Emex spinosa) or prickles (Hedysarum spinosissimum). Certainly neither type uses red coloration as advertisement to attract the seed dispersing agents. Fleshy-fruited species (Rhamnus alaternus, Rubus sanguineus and Pistacia sp.), which disperse their seeds via frugivores, change fruit color from green to red while still unripe and then to black or dark blue upon ripening. The red color does not seem to function primarily in dispersal (unless red fruits form advertisement flags when there are already black ripe fruits on the plant) because the red unripe fruits of these species are poisonous, spiny, or unpalatable. The unripe red fruits of Nerium oleander are very poisonous, those of Rhamnus alaternus and Anabasis articulata are moderately poisonous, those of Rubus sanguineus are very sour, those of Pistacia sp. contain unpalatable resin and those of Emex spinosa and Hedysarum spinosissimum are prickly. We propose that these unripe red fruits are aposematic, protecting them from herbivory before seed maturation.     

Sporogenic Effect of Polyunsaturated Fatty Acids on Development of Aspergillus spp.

Aspergillus spp. are frequently occurring seed-colonizing fungi that complete their disease cycles through the development of asexual spores, which function as inocula, and through the formation of cleistothecia and sclerotia. We found that development of all three of these structures in Aspergillus nidulans, Aspergillus flavus, and Aspergillus parasiticus is affected by linoleic acid and light. The specific morphological effects of linoleic acid include induction of precocious and increased asexual spore development in A. flavus and A. parasiticus strains and altered sclerotium production in some A. flavus strains in which sclerotium production decreases in the light but increases in the dark. In A. nidulans, both asexual spore production and sexual spore production were altered by linoleic acid. Spore development was induced in all three species by hydroperoxylinoleic acids, which are linoleic acid derivatives that are produced during fungal colonization of seeds. The sporogenic effects of these linoleic compounds on A. nidulans are similar to the sporogenic effects of A. nidulans psi factor, an endogenous mixture of hydroxylinoleic acid moieties. Light treatments also significantly increased asexual spore production in all three species. The sporogenic effects of light, linoleic acid, and linoleic acid derivatives on A. nidulans required an intact veA gene. The sporogenic effects of light and linoleic acid on Aspergillus spp., as well as members of other fungal genera, suggest that these factors may be significant environmental signals for fungal development.     

External Loops at the C Terminus of Erwinia chrysanthemi Pectate Lyase C Are Required for Species-Specific Secretion through the Out Type II Pathway

The type II secretion system (main terminal branch of the general secretion pathway) is used by diverse gram-negative bacteria to secrete extracellular proteins. Proteins secreted by this pathway are synthesized with an N-terminal signal peptide which is removed upon translocation across the inner membrane, but the signals which target the mature proteins for secretion across the outer membrane are unknown. The plant pathogens Erwinia chrysanthemi and Erwinia carotovora secrete several isozymes of pectate lyase (Pel) by the out-encoded type II pathway. However, these two bacteria cannot secrete Pels encoded by heterologously expressed pel genes from the other species, suggesting the existence of species-specific secretion signals within these proteins. The functional cluster of E. chrysanthemi out genes carried on cosmid pCPP2006 enables Escherichia coli to secrete E. chrysanthemi, but not E. carotovora, Pels. We exploited the high sequence similarity between E. chrysanthemi PelC and E. carotovora Pel1 to construct 15 hybrid proteins in which different regions of PelC were replaced with homologous sequences from Pel1. The differential secretion of these hybrid proteins by E. coli(pCPP2006) revealed M118 to D175 and V215 to C329 as regions required for species-specific secretion of PelC. We propose that the primary targeting signal is contained within the external loops formed by G274 to C329 but is dependent on residues in M118 to D170 and V215 to G274 for proper positioning.     

Identification of Critical Regions and Candidate Genes for Cardiovascular Malformations and Cardiomyopathy Associated with Deletions of Chromosome 1p36

Cardiovascular malformations and cardiomyopathy are among the most common phenotypes caused by deletions of chromosome 1p36 which affect approximately 1 in 5000 newborns. Although these cardiac-related abnormalities are a significant source of morbidity and mortality associated with 1p36 deletions, most of the individual genes that contribute to these conditions have yet to be identified. In this paper, we use a combination of clinical and molecular cytogenetic data to define five critical regions for cardiovascular malformations and two critical regions for cardiomyopathy on chromosome 1p36. Positional candidate genes which may contribute to the development of cardiovascular malformations associated with 1p36 deletions include DVL1, SKI, RERE, PDPN, SPEN, CLCNKA, ECE1, HSPG2, LUZP1, and WASF2. Similarly, haploinsufficiency of PRDM16–a gene which was recently shown to be sufficient to cause the left ventricular noncompaction–SKI, PRKCZ, RERE, UBE4B and MASP2 may contribute to the development of cardiomyopathy. When treating individuals with 1p36 deletions, or providing prognostic information to their families, physicians should take into account that 1p36 deletions which overlie these cardiac critical regions may portend to cardiovascular complications. Since several of these cardiac critical regions contain more than one positional candidate gene–and large terminal and interstitial 1p36 deletions often overlap more than one cardiac critical region–it is likely that haploinsufficiency of two or more genes contributes to the cardiac phenotypes associated with many 1p36 deletions.     

Sesquiterpenoids as chemosystematic markers in the subtribe Hypochaeridinae (Lactuceae,Asteraceae)

Sesquiterpene lactones are well established as chemosystematic markers in the Asteraceae family. From the Lactuceae tribe of the Asteraceae family a large number of sesquiterpene lactones – mainly of the guaiane type – have been isolated. One of the 11 subtribes of the Lactuceae recognized by Bremer is the subtribe Hypochaeridinae, which encompasses 10 genera with approximately 170 species. The present communication summarizes the sesquiterpene derivatives reported from these 10 genera, points out, which constituents are characteristic for particular groups, and discusses the occurrence of these secondary metabolites in a chemosystematic context. To this end, each of the reported sesquiterpenoids reported for the Hypochaeridinae is classified into one of three main compound classes (MCCs; eudesmane-, germacrane-, guaiane-derivatives) and into one of a number of compound classes (CCs) within these principal groups. The distribution of sesquiterpenoids belonging to these particular classes of sesquiterpenoids generally follows the currently accepted generic limits. However, the genus Helminthoteca, which is included into Picris by many authors, possesses an array of compounds implying a closer relationship to the genus Hypochaeris than to the remainder of the genus Picris. Furthermore, Leontodon subgenus Oporinia shows closer similarity in secondary metabolite patterns to the genus Picris than to Leontodon subgenus Leontodon. On the other hand Leontodon subgenus Leontodon has more chemical characters in common with the genus Hedypnois than with Leontodon subgenus Oporinia. These findings are in-line with recent results of molecular analyses, which imply that current generic limits within the Hypochaeridinae might not reflect the phylogeny of the subtribe.     

Molecular evolution of the actin-like MreB protein gene family in wall-less bacteria

The mreB gene family encodes actin-like proteins that determine cell shape by directing cell wall synthesis and often exists in one to three copies in the genomes of non-spherical bacteria. Intriguingly, while most wall-less bacteria do not have this gene, five to seven mreB homologs are found in Spiroplasma and Haloplasma, which are both characterized by cell contractility. To investigate the molecular evolution of this gene family in wall-less bacteria, we sampled the available genome sequences from these two genera and other related lineages for comparative analysis. The gene phylogenies indicated that the mreB homologs in Haloplasma are more closely related to those in Firmicutes, whereas those in Spiroplasma form a separate clade. This finding suggests that the gene family expansions in these two lineages are the results of independent ancient duplications. Moreover, the Spiroplasma mreB homologs can be classified into five clades, of which the genomic positions are largely conserved. The inference of gene gains and losses suggests that there has been an overall trend to retain only one homolog from each of the five mreB clades in the evolutionary history of Spiroplasma.     

Isolation of Marine Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Cycloclasticus Strains from the Gulf of Mexico and Comparison of Their PAH Degradation Ability with That of Puget Sound Cycloclasticus Strains

Phenanthrene- and naphthalene-degrading bacteria were isolated from four offshore and nearshore locations in the Gulf of Mexico by using a modified most-probable-number technique. The concentrations of these bacteria ranged from 10² to 10⁶ cells per ml of wet surficial sediment in mildly contaminated and noncontaminated sediments. A total of 23 strains of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria were obtained. Based on partial 16S ribosomal DNA sequences and phenotypic characteristics, these 23 strains are members of the genus Cycloclasticus. Three representatives were chosen for a complete phylogenetic analysis, which confirmed the close relationship of these isolates to type strain Cycloclasticus pugetii PS-1, which was isolated from Puget Sound. PAH substrate utilization tests which included high-molecular-weight PAHs revealed that these isolates had similar, broad substrate ranges which included naphthalene, substituted naphthalenes, phenanthrene, biphenyl, anthracene, acenaphthene, and fluorene. Degradation of pyrene and fluoranthene occurred only when the strains were incubated with phenanthrene. Two distinct partial PAH dioxygenase iron sulfur protein (ISP) gene sequences were PCR amplified from Puget Sound and Gulf of Mexico Cycloclasticus strains. Phylogenetic analyses of these sequences revealed that one ISP type is related to the bph type of ISP sequences, while the other ISP type is related to the nah type of ISP sequences. The predicted ISP amino acid sequences for the Gulf of Mexico and Puget Sound strains are identical, which supports the hypothesis that these geographically separated isolates are closely related phylogentically. Cycloclasticus species appear to be numerically important and widespread PAH-degrading bacteria in both Puget Sound and the Gulf of Mexico.