Thysanoptera of Bulgaria

The present checklist includes data on the species composition, geographic distribution and feeding preferences of thrips species in Bulgaria. In total, 155 species in 48 genera are listed. Of these, 125 species belong to suborder Terebrantia and include 103 species of 33 genera in family Thripidae, 14 species of two genera in Aeolothripidae, seven species of two genera in Melanthripidae and one species in Fauriellidae. In suborder Tubulifera, 30 species of 10 genera in the single family Phlaeothripidae are listed. Of the 155 Bulgarian thrips species, 87.7% are phytophagous, 4.5% are obligate predators, 5.8% are mycophagous and 1.9% are with unknown feeding preferences. Fourteen pest species are listed for Bulgaria, of which Frankliniella occidentalis, Thrips tabaci and Haplothrips tritici are of economic importance. The list provides detailed information on the horizontal and vertical distribution of Thysanoptera in 5 regions and 45 subregions of Bulgaria. The present paper also includes an evaluation of the biodiversity of Thysanoptera and the extent to which each region of the country has been studied.     

An Extensive Comparison of the Effect of Anthelmintic Classes on Diverse Nematodes

Soil-transmitted helminths are parasitic nematodes that inhabit the human intestine. These parasites, which include two hookworm species, Ancylostoma duodenale and Necator americanus, the whipworm Trichuris trichiura , and the large roundworm Ascaris lumbricoides , infect upwards of two billion people and are a major cause of disease burden in children and pregnant women. The challenge with treating these diseases is that poverty, safety, and inefficient public health policy have marginalized drug development and distribution to control infection in humans. Anthelmintics (anti-worm drugs) have historically been developed and tested for treatment of non-human parasitic nematodes that infect livestock and companion animals. Here we systematically compare the in vitro efficacy of all major anthelmintic classes currently used in human therapy (benzimidazoles, nicotinic acetylcholine receptor agonists, macrocyclic lactones, nitazoxanide) against species closely related to human parasitic nematodes-Ancylostoma ceylanicum, Trichuris muris , and Ascaris suum --- as well as a rodent parasitic nematode used in veterinary drug discovery, Heligmosomoides bakeri , and the free-living nematode Caenorhabditis elegans. Extensive in vitro data is complemented with single-dose in vivo data in three rodent models of parasitic diseases. We find that the effects of the drugs in vitro and in vivo can vary greatly among these nematode species, e.g., the efficacy of albendazole is strong on A. ceylanicum but weak on H . bakeri . Nonetheless, certain commonalities of the in vitro effects of the drugs can be seen, e.g., nitazoxanide consistently shows an all-or-nothing response. Our in vitro data suggest that further optimization of the clinical efficacy of some of these anthelmintics could be achieved by altering the treatment routine and/or dosing. Most importantly, our in vitro and in vivo data indicate that the hookworm A. ceylanicum is a particularly sensitive and useful model for anthelmintic studies and should be incorporated early on in drug screens for broad-spectrum human soil-transmitted helminth therapies.     

Checklist of the Cecidomyiidae (Diptera) of Finland

A list of the 356 species of Cecidomyiidae (Diptera) recorded from Finland is presented, which comprises 6 Lestremiinae, 156 Micromyinae, 16 Winnertziinae, 69 Porricondylinae, and 109 Cecidomyiinae. The faunistic knowledge of Finnish Winnertziinae, Porricondylinae and Cecidomyiinae is regarded as particularly poor. Based on species numbers known from other countries in Europe, a conservative estimate is 700–800 species of Cecidomyiidae actually occurring in Finland.     

The narA Locus of Synechococcus sp. Strain PCC 7942 Consists of a Cluster of Molybdopterin Biosynthesis Genes

The narA locus required for nitrate reduction in Synechococcus sp. strain PCC 7942 is shown to consist of a cluster of genes, namely, moeA, moaC, moaD, moaE, and moaA, involved in molybdenum cofactor biosynthesis. The product of the moaC gene of strain PCC 7942 shows homology in its N-terminal half to MoaC from Escherichia coli and in its C-terminal half to MoaB or Mog. Overexpression of the Synechococcus moaC gene in E. coli resulted in the synthesis of a polypeptide of 36 kDa, a size that would conform to a protein resembling a fusion of the MoaC and MoaB or Mog polypeptides of E. coli. Insertional inactivation of the moeA, moaC, moaE, and moaA genes showed that the moeA-moa gene cluster is required for growth on nitrate and expression of nitrate reductase activity in strain PCC 7942. The moaCDEA genes constitute an operon which is transcribed divergently from the moeA gene. Expression of the moeA gene and the moa operon was little affected by the nitrogen source present in the culture medium.     

Spatial distribution of brood-bearing females of limnetic species of Cladocera

In this study, the spatial distribution of brood-bearing females of five species of limnetic cladocerans (Daphnia cucullata, D. longispina, Bosmina coregoni, B. longirostris, Diaphanosoma brachyurum) in the deep mesotrophic lake in relation to the predation pressure of planktivorous fish (roach Rutilus rutilus, perch Perca fluviatilis, catfish Ictalurus nebulosus, white fish Coregonus albula, bleak Alburnus alburnus), and planktonic invertebrates (cyclopoids Mesocyclops leuckartii, Thermocyclops oithonoides, T. crassus, and cladoceran Leptodora kindtii) as well as some environmental variables was estimated. Most cladocerans showed apparent differences in horizontal distribution (ANOVA F = 0.2–0.45, P < 0.05) in the littoral zone and lack of such differences in the pelagic zone (F = 0.07–0.13, P > 0.05). Vertical distribution of most species, in turn, showed a clear pattern in the pelagic zone (F = 0.31–0.39, P < 0.05) and less regularities in the littoral zone (F = 0.15–029, P > 0.05). The differences in spatial distribution of non-predated and predated species suggest that predation pressure, but not predatory type, was an important factor structuring their distribution. Other factors that affected their distribution were conductivity, dissolved oxygen, TOC and macrophyte biomass; however, most of those variables better explained the distribution of brood-bearing cladocerans in the vertical than horizontal aspect.     

Intertidal zonation of prosobranch gastropods: Analysis of densities of four co-existing species

The densities of populations of Nerita atramentosa Reeve, Austrocochlea constricta Lamarck, Bembiciuin nanum (Lamarck), and Cellana tramoserica (Sowerby) were recorded in 0.25 m² quadrats on landward and seaward halves of a sheltered and a moderately exposed rock platform from June 1972 to June 1973. The data have been subjected to variance and multiple regression analysis. Differences between densities of each species on the two shores and in the two areas of each shore are discussed with respect to the regressions on littoral height. Densities of Nerita on the sheltered shore, Austrocochlea and Bembicium on both shores, and Cellana, on the exposed shore, increased with height. The density of Cellana on the sheltered shore decreased as height increased. The density differences in the landward and seaward areas on the two shores were attributable to the effect of height for Nerita and Austrocochlea. Height was the major variable affecting the density of these two species on the sheltered shore. Bembicium and Cellana densities on both shores, and Austrocochlea density on the exposed shore, are not primarily determined by height.On the sheltered shore, Nerita and Cellana increased in density with increasing cover of water in rock pools. On the exposed shore, Bembicium and Cellana became sparser with increasing water cover. Bembicium on both shores increased in density with increasing cover of the alga Peyssonelia, as did Cellana on the exposed shore. Cellana and Austrocochlea tended to increase in density with Nerita on the sheltered shore. Cellana tended to be sparse where Bembicium was dense on the exposed shore. The biological effects of substrata and other species on the densities of each species remain unexplained.Significant time effects were found for variations in the densities of Nerita and Cellana on the sheltered shore and of Austrocochlea and Cellana on the exposed shore. The seasonal change in density of Nerita was parabolic with a minimum in summer, and is consistent with the known period of recruitment of this species. The lack of significant time effects on density of Austrocochlea on the sheltered shore is consistent with the known continuous recruitment of this species. The declining density of Austrocochlea on the moderately exposed shore was found, by size-frequency analysis, to be due to reduced recruitment compared with surrounding shores. The density of Cellana on both shores showed seasonal changes, with a maximum in summer, which is consistent with the known period of recruitment in Cellana. The lack of seasonal changes in density of Bembicium is briefly discussed.This type of multifactor analysis identifies biological interactions affecting variation in density of these species. It also corroborates the results of other ecological investigations and determines the relative importance of a variety of physical and biological factors in the distribution of density of intertidal gastropods.     

The rate of allelism of lethal genes in a geographically structured population

The expected rate of allelism, E[I(x)], of lethal genes between two colonies with distance x in a structured population is studied by using one- and two-dimensional stepping-stone models. It is shown that E[I(x)] depends on the magnitude of selection in heterozygous condition (h), the rate of migration among adjacent colonies (m), the number of loci which produce lethal mutations (n) and the effective population size of each colony (N).——E[I(x)] always decreases with distance x. The rate of decrease is affected strongly by the magnitude of m. The rate of decrease is faster when m is small. E[I(x)] also decreases with increasing N and n. The effect of h on E[I(x)] is somewhat complicated. However, E[I(0)] is always smaller when h is small than when it is large.——For large x, the following approximate formulae may be obtained: (see PDF) where q and Var (q) are the mean and the variance of gene frequencies in each colony, t is approximated as t=h, (see PDF), -h for the partially recessive, completely recessive, and overdominant lethals, respectively, and C₀ is a function of m and t. It is clear that E[I(x)] declines exponentially with x in a one-dimensional habitat. The decrease E[I(x)] is faster in a two-dimensional habitat than in a one-dimensional habitat. The present result is applied to some of the existing data and the estimation of population parameters is also discussed.     

Contents of the poison apparatus of some species of Pheidole ants

Four Old World species of Pheidole ants contain different mixtures of farnesene-type hydrocarbons in their poison apparatus, and the mixture is different between the minor and major workers within a species. A bishomofarnesene (C₁₇H₂₈) provides approximately half of the secretion of the Dufour glands of minor workers of Pheidole pallidula. (Z,E)-α-Farnesene constituted 96% of the Dufour secretion of major workers of P. pallidula, but only 20% of that of minors. The Dufour glands of minor workers of Pheidole sinaitica contain a mixture of farnesene homologues with (Z,E)-α-farnesene and the bishomofarnesene also found in P. pallidula predominant. The mixture in major workers was similar but had, in addition, a small amount of (E)-β-farnesene. The Dufour glands of Pheidole teneriffana minors contain chiefly the same bishomofarnesene found in P. pallidula and P. sinaitica while major workers contain (Z,E)-α-farnesene. Pheidole megacephala minor workers contained small amounts of eight farnesenes, while major workers contained essentially no farnesenes. The poison glands of minor workers of P. pallidula contain 3-ethyl-2,5-dimethylpyrazine. No pyrazine compounds were found in the major workers of P. pallidula or the minor workers of P. sinaitica. The poison glands of the major workers of P. sinaitica contained larger amounts of tetra-substituted pyrazines. No pyrazines were found in the poison reservoirs of major or minor workers of P. teneriffana or P. megacephala.     

Natural diversity of nodular microsymbionts of Myrica rubra

Myrica is often considered a promiscuous actinorhizal genus. However, there are large differences in diversity among Myrica spp., and M. gale does not exhibit such promiscuity in its natural environment. In order to understand the diversity of nodular microsymbionts of M. rubra in natural environments and whether or not the M. rubra is a `promiscuous' host, we studied the natural diversity of nodular microsymbionts of different cultivars of M. rubra. 15 nodules from nine horticultural cultivars of M. rubra were collected in 7 sites of eastern, southeastern, central and northern part of Zhejiang province, China. Unisolated strains were compared by sequence analyses of their nifD-nifK intergenic spacers and PCR amplification protocol on nodules. Phylogenetic relationships among nodular Frankia strains were analyzed by comparing sequences of their nifD-nifK intergenic spacers and reference strains. There is a high degree of diversity among nodular Frankia symbionts of M. rubra. Frankia strains from cluster I and cluster III were found in nodules from many different cultivars of M. rubra. Furthermore, there were sometimes two strains which belong to different infective clusters of Frankia in the same nodule, and Frankia strains of cluster I were often dominant strains when there were two strains. M. rubra can thus be considered to be promiscuous in nature. Identical sequences in nodules from different plants at widely separated sites were commonly found, indicating that some strains are cosmopolitan. Geographic separation, host selectivity for Frankia symbionts and soil environment may account for the diversity of Frankia strains and differences in Frankia populations found in M. rubra nodules. Several very closely related local Frankia populations in M. rubra nodules could be distinguished from one another by our approach.     

DNA barcoding of euryglossine bees and the description of new species of Euhesma Michener (Hymenoptera,Colletidae, Euryglossinae)

This paper launches an open access DNA barcoding project “AUSBS” under the Barcoding of Life Datasystems (BOLD). The aims of the project are to help scientists who lack the necessary morphological knowledge to identify known species using molecular markers, to aid native bee specialists with the recognition of species groups that morphologically are difficult to define, and, eventually, to assist with the recognition of new species among known species. Using integrative taxonomy, i.e. morphological comparison to type specimens in Australian museum collections combined with phylogenetic analysis of a fragment of the mitochondrial DNA cytochrome c oxidase subunit I (mtCOI) gene sequences led to the recognition of four new species of Euhesma Michener (Hymenoptera: Colletidae: Euryglossini) collected during intensive surveys in remote Australian conservation areas, which are described. The new species are Euhesma micans, Euhesma lyngouriae, and Euhesma aulaca in a species group associated with Eremophila flowers, and Euhesma albamala in the walkeriana species group.     

The effect of aerobic exercise on the expression of genes in skeletal muscles of trained and untrained men

It is well recognized that PGC-1α protein is a key regulator of mitochondrial biogenesis. Mechanical and metabolic perturbations in a skeletal muscle during and after aerobic exercise lead to an increased expression of PGC-1α gene. This increased expression of PGC-1α gene after exercise depends on the relative workload intensity and does not depend on the fitness level. The goal of this study was to compare mRNA expression of PGC-1α, TFAM, and TFB2M regulators of mitochondrial biogenesis and FOXO1 and Atrogin-1 proteolysis-related genes in a skeletal muscle of untrained and trained men after aerobic exercise with the same relative workload. This study showed that PGC-1α gene expression after exercise was the same in the two groups, but the expression of TFAM and TFB2M genes was higher in untrained muscles than in trained ones. In contrast, the expression of FOXO1 and Atrogin-1 genes increased only in the muscles of trained men.     

Evolution of a New Gene Substituting for the leuD Gene of Salmonella typhimurium: Characterization of supQ Mutations

Alpha-isopropylmalate isomerase, the second specific enzyme in the biosynthesis of leucine, is coded for by two genes, leuC and leuD. Leucine auxotrophs, harboring leuD mutations including a deletion of the entire leuD gene, revert to leucine prototrophy owing to mutations at a locus, supQ, substantially distant to the leucine operon. A large number of independently isolated supQ mutations were characterized. A significant increase in the spontaneous frequency of supQ mutations was found after mutagenesis with 2-aminopurine, N-methyl-N′-nitro-N-nitrosoguanidine, diethyl sulfate, and nitrous acid. The supQ function in most of these strains is temperature sensitive, resulting in more efficient suppression with decreasing temperature. At higher temperatures, the supQ limits the growth rate of leuD supQ mutant strains. All supQ mutations are co-transducible with proA and proB, with co-transduction frequencies ranging from 5.4 to 99.9% for different supQ mutations. Many supQ mutations were isolated, especially after nitrous acid mutagenesis, that had acquired a simultaneous proline requirement. The data support the idea of two genes, supQ and newD, whose protein products form a complex. The newD gene product, without any genetic alteration, is capable of substituting for the missing leuD protein. However, mutations in the supQ gene (point mutations or deletions) are necessary to make the newD protein available, which is normally tied up in a complex with the supQ protein.     

Growth,allometry and shade tolerance of understory saplings of four subalpine conifers in central Japan

The conifers Abies veitchii, A. mariesii, Picea jezoensis var. hondoensis, Tsuga diversifolia dominate in subalpine forests in central Japan. We expected that species differences in shade tolerance and in aboveground and belowground architecture are important for their coexistence. We examined net production and carbon allocation of understory saplings. Although the four species allocated similar amounts of biomass to roots at a given trunk height, the root-zone area of T. diversifolia was greater than that of the three other species. T. diversifolia often dominates shallow soil sites, such as ridge and rocky slopes, and, therefore, a wide spread of lateral roots would be an adaptation to such edaphic conditions. Crown width and leaf and branch mass were greatest for T. diversifolia and A. mariesii, followed in order by A. veitchii and P. jezoensis var. hondoensis. Although leaf mass of P. jezoensis var. hondoensis was lowest among the four species, species differences were not found in the net production per sapling because net production per leaf mass was greatest for P. jezoensis var. hondoensis. The leaf lifespan was longer in the order A. mariesii, T. diversifolia, P. jezoensis var. hondoensis and A. veitchii. The minimum rate of net production per leaf mass required to maintain the current sapling leaf mass (MRNP_LM) was lowest in A. mariesii and T. diversifolia, and increased in the order of A. veitchii and P. jezoensis var. hondoensis. A. mariesii and T. diversifolia may survive in shade conditions by a lower MRNP_LM than the two other species. Therefore, species differences in aboveground and belowground architecture and MRNP_LM reflected their shade tolerance and regeneration strategies, which contribute to their coexistence.     

Root Exudates of Various Host Plants of Rhizobium leguminosarum Contain Different Sets of Inducers of Rhizobium Nodulation Genes

Rhizobium promoters involved in the formation of root nodules on leguminous plants are activated by flavonoids in plant root exudate. A series of Rhizobium strains which all contain the inducible Rhizobium leguminosarum nodA promoter fused to the Escherichia coli lacZ gene, and which differ only in the source of the regulatory nodD gene, were recently used to show that the regulatory nodD gene determines which flavonoids are able to activate the nodA promoter (HP Spaink, CA Wijffelman, E Pees, RJH Okker, BJJ Lugtenberg 1987 Nature 328: 337-340). Since these strains therefore are able to discriminate between various flavonoids, they were used to determine whether or not plants that are nodulated by R. leguminosarum produce different inducers. After chromatographic separation of root exudate constituents from Vicia sativa L. subsp. nigra (L.), V. hirsuta (L.) S.F. Gray, Pisum sativum L. cv Rondo, and Trifolium subterraneum L., the fractions were tested with a set of strains containing a nodD gene of R. leguminosarum, R. trifolii, or Rhizobium meliloti, respectively. It appeared that the source of nodD determined whether, and to what extent, the R. leguminosarum nodA promoter was induced. Lack of induction could not be attributed to the presence of inhibitors. Most of the inducers were able to activate the nodA promoter in the presence of one particular nodD gene only. The inducers that were active in the presence of the R. leguminosarum nodD gene were different in each root exudate.     

Prevalence of simian malaria parasites in macaques of Singapore

Plasmodium knowlesi is a simian malaria parasite currently recognized as the fifth causative agent of human malaria. Recently, naturally acquired P. cynomolgi infection in humans was also detected in Southeast Asia. The main reservoir of both parasites is the long-tailed and pig-tailed macaques, which are indigenous in this region. Due to increased urbanization and changes in land use, there has been greater proximity and interaction between the long-tailed macaques and the general population in Singapore. As such, this study aims to determine the prevalence of simian malaria parasites in local macaques to assess the risk of zoonosis to the general human population. Screening for the presence of malaria parasites was conducted on blood samples from 660 peridomestic macaques collected between Jan 2008 and Mar 2017, and 379 wild macaques collected between Mar 2009 and Mar 2017, using a Pan-Plasmodium-genus specific PCR. Positive samples were then screened using a simian Plasmodium species-specific nested PCR assay to identify the species of parasites (P. knowlesi, P. coatneyi, P. fieldi, P. cynomolgi, and P. inui) present. All the peridomestic macaques sampled were tested negative for malaria, while 80.5% of the 379 wild macaques were infected. All five simian Plasmodium species were detected; P. cynomolgi being the most prevalent (71.5%), followed by P. knowlesi (47.5%), P. inui (42.0%), P. fieldi (32.5%), and P. coatneyi (28.5%). Co-infection with multiple species of Plasmodium parasites was also observed. The study revealed that Singapore’s wild long-tailed macaques are natural hosts of the five simian malaria parasite species, while no malaria was detected in all peridomestic macaques tested. Therefore, the risk of simian malaria transmission to the general human population is concluded to be low. However, this can be better demonstrated with the incrimination of the vectors of simian malaria parasites in Singapore.     

Genetic analyses of reddish-brown polyoxin-resistant mutants of Bipolaris maydis

In the southern corn blight fungus, Bipolaris maydis, five polyoxin-resistance genes (Pol1 to Pol5) have been reported. Pol2 and Pol5 are pleiotropic for not only polyoxin resistance but also reddish brown colonies. Here, we used a comparative genomics approach to identify Pol2 and Pol5 at a molecular genetics level. Our analysis revealed that nucleotide sequence variations in the genes for hydroxymethylbilane synthase (HMBS) and ferrochelatase (FECH) were linked to the phenotypes of Pol2 and Pol5, respectively. Further variations in the nucleotide sequences of these genes were also found in other strains of Pol2 and Pol5. Complementation tests with the wild type genes confirmed that these mutations at Hmbs and Fech were responsible for the polyoxin resistance in the Pol2 and Pol5 mutants. The deletion mutants of these genes (ΔHMBS and ΔFECH) were conditionally lethal without exogenous heme. The heme contents of Pol2 and Pol5 mutants were lower than that in the wild type, suggesting that the mutations in hmbs and fech reduced the functions of HMBS and FECH, although neither was completely inactivated. These results suggested Pol2 and Pol5 encode HMBS and FECH, members of enzymes in the heme-biosynthetic pathway of this fungus.     

Comparison of the extent of genetic variation of Vallisneria natans and its sympatric congener V. spinulosa in lakes of the middle-lower reaches of the Yangtze River

Vallisneria natans and Vallisneria spinulosa are two morphologically very similar and sympatrically dominant submerged macrophytes in lakes of the middle-lower reaches of the Yangtze River. Genetic variation was compared based on a total of 196 individuals from six V. natans populations and 201 individuals from seven V. spinulosa populations. Using eight ISSR primers, a total of 139 and 129 DNA fragments were generated with 121 being polymorphic in V. natans and 99 in V. spinulosa. The two species maintained higher genetic variation both at the species and population levels in comparison with other aquatic macrophytes. A higher level of genetic diversity among populations was found in V. natans than in V. spinulosa: the percentage of polymorphic loci (PPL) in V. natans was 52-62% vs. 38-47% in V. spinulosa; gene diversity (H) was 0.21 in V. natans vs. 0.17 in V. spinulosa.Both an analysis of molecular variance (AMOVA) and F-estimation (F_ST) showed that most of the total genetic variation resided within populations of both species (AMOVA: 85% and 80%; F_ST: 0.132 and 0.202), indicating low genetic differentiation between populations. Principal coordinates analysis (PCA) indicated evident gene flow between populations of both species. The outcrossing reproductive mode and pervasive gene flow might have played important roles in maintaining high genetic diversity and in shaping low population differentiation of the two Vallisneria species, while the extent of clonal growth might account for the different levels of population divergence between them.     

Involvement of recF, recO, and recR Genes in UV-Radiation Mutagenesis of Escherichia coli

The recF, recO, and recR genes were originally identified as those affecting the RecF pathway of recombination in Escherichia coli cells. Several lines of evidence suggest that the recF, recO, and recR genes function at the same step of recombination and postreplication repair. In this work, we report that null mutations in recF, recO, or recR greatly reduce UV-radiation mutagenesis (UVM) in an assay for reversion from a Trp⁻ (trpE65) to a Trp⁺ phenotypes. Introduction of the defective lexA51 mutation [lexA51(Def)] and/or UmuD′ into recF, recO, and recR mutants failed to restore normal UVM in the mutants. On the other hand, the presence of recA2020, a suppressor mutation for recF, recO, and recR mutations, restored normal UVM in recF, recO, and recR mutants. These results indicate an involvement of the recF, recO, and recR genes and their products in UVM, possibly by affecting the third role of RecA in UVM.