Diversity among bacteria causing blotch disease on the commercial mushroom, agaricus bisporus /

A total of 251 bacterial isolates were isolated from blotched mushroom samples obtained from various mushroom farms in Canada. Out of 251 stored isolates, 170 isolates were tested for pathogenicity on Agaricus bisporus through mushroom rapid pitting test with three distinct pathotypes observed: dark brown, brovm and yellow/yellow-brown blotch. Phenotypic analysis of 83 isolates showed two distinct proteinase K resistant peptide profiles. Profile group A isolates exhibited peptides with masses of 45, 18, 16 and 14 kDa and fiirther biochemical tests identified them as Pseudomonasfluorescens III and V. Profile group B isolates lacked the 16-kDa peptide and the blotch causing bacterial isolates of this group was identified as Serratia liquefaciens and Cedecea davisae. Comparative genetic analysis using Amplified Fragment Length Polymorphism (AFLP) on 50 Pseudomonas sp. isolates (Group A) showed that various blotch symptoms were caused by isolates distributed throughout the Pseudomonas sp. clusters with the exception of the Pseudomonas tolaasii group and one non-pathogenic Pseudomonas fluorescens cluster. These results show that seven distinct Pseudomonas sp. genotypes (genetic clusters) have the ability to cause various symptoms of blotch and that AFLP can discriminate blotch causing from non-blotch causing Pseudomonasfluorescens. Therefore, a complex of diverse bacterial organisms causes bacterial blotch disease

Phytoplankton species diversity of 27 lakes and ponds of Costa Rica (Central America)

The literature on species diversity of phytoplankton of tropical lakes is scarce, and for the main part comes from studies of the big lakes in Africa, or deep lakes in South America, leaving a gap in the information about small shallow tropical lakes. In the present work the phytoplankton species composition and diversity of 27 shallow lakes and ponds in Costa Rica (Central America) was studied. The species composition was found to agree with other studies of tropical lakes, with a dominance of Chlorophyta, Cyanophyta, or in some cases Bacillariophyta or Euglenophyta; and a general paucity of Chrysophyta and Cryptophyta. Species richness varied considerably among the lakes, and tended to decrease with an increase in lake elevation. A low evenness in the species abundances was found, with one or more species outnumbering the rest by several orders of magnitude. Individual species abundances and species composition was found to vary with time in Rio Cuarto Lake, a meromictic lake situated in a region with low seasonal change in precipitation. In comparison with the phytoplankton of temperate lakes, the phytoplankton of the tropical lakes studied tended to have a lower evenness of species abundances, although species richness may be similar to temperate figures in some cases. Diversity indices sensitive to changes in the abundance of rare species tend to be higher in the tropical lakes studied; diversity indices sensitive to changes in the numbers of abundant species tend to be similar between the temperate and tropical lakes examined.

The identification and characterization of inter- and intra-species genetic diversity derived from retrotransposons in humans

Retrotransposons, which used to be considered as “junk DNA”, have begun to reveal their immense value to genome evolution and human biology due to recent studies. They consist of at least ~45% of the human genome and are more or less the same in other mammalian genomes. Retrotransposon elements (REs) are known to affect the human genome through many different mechanisms, such as generating insertion mutations, genomic instability, and alteration in gene expression. Previous studies have suggested several RE subfamilies, such as Alu, L1, SVA and LTR, are currently active in the human genome, and they are an important source of genetic diversity between human and other primates, as well as among humans. Although several groups had used Retrotransposon Insertion Polymorphisms (RIPs) as markers in studying primate evolutionary history, no study specifically focused on identifying Human-Specific Retrotransposon Element (HS-RE) and their roles in human genome evolution. In this study, by computationally comparing the human genome to 4 primate genomes, we identified a total of 18,860 HS-REs, among which are 11,664 Alus, 4,887 L1s, 1,526 SVAs and 783 LTRs (222 full length entries), representing the largest and most comprehensive list of HS-REs generated to date. Together, these HS-REs contributed a total of 14.2Mb sequence increase from the inserted REs and Target Site Duplications (TSDs), 71.6Kb increase from transductions, and 268.2 Kb sequence deletion of from insertion-mediated deletion, leading to a net increase of ~14 Mb sequences to the human genome. Furthermore, we observed for the first time that Y chromosome might be a hot target for new retrotransposon insertions in general and particularly for LTRs. The data also allowed for the first time the survey of frequency of TE insertions inside other TEs in comparison with TE insertion into none-TE regions. In summary, our data suggest that retrotransposon elements have played a significant role in the evolution of Homo sapiens.

Diversity in Structural and Spectural Characteristics of Some Transition Metal Complexes Derived From Aldehyde Based Thiosemicarbazone Ligands

The study deals with the diversity in structural and spectural characteristics of some transition metal complexes derived from aldehyde based thiosemicarbazone ligands thiosemicarbazones are a family of compounds with beneficial biological activity viz., anticancer,antitumour, antifungal, antibacterial, antimalarial, antifilarial, antiviral and anti-HIV activities. Many thiosemicarbazone ligands and their complexes have been prepared and screened for their antimicrobial activity against various types of fungi and bacteria. The results prove that the compounds exhibit antimicrobial properties and it is important to note that in some cases metal chelates show more inhibitory effects than the parent ligands. The increased lipophilicity of these complexes seems to be responsible for their enhanced biological potency. Adverse biological activities of thiosemicarbazones have been widely studied in rats and in other species. The parameters measured show that copper complexes caused considerable oxidative stress and zinc zinc complexes behaved as antioxidants. It has applications on analytical field also. Some thiosemicarbazones produce highly colored complexes with metal ions. This thesis aims to synthesis some novel thiosemicarbazone ligands and their transition metal complexes together with their physico-chemical characterization.

Simple and Encapsulated Transition Metal Complexes of Schiff Bases Derived from Quinoxaline-2-Carboxaldehyde and Diamines: Biological and Catalytic Activity Studies

This thesis is mainly concerned with the synthesis and characterisation of new simple and zeolite encapsulated transition metal (manganese(II),nickel(II),and copper(II)complexes of quinoxaline based double Schiff base ligands.Theses ligands are N,N'-bis(quinoxaline-2-carboxalidene)hydrazine,N,N'-bis(quinoxaline-2-carboxalidene)-1,2-diaminoethane,N,N'-bis(quinoxaline-2-carboxalidene)-1,3-diamonopropane,N,N'-bis(quinoxaline-2-carboxalidene)-1,4-diaminobutane,N,N'-bis(quinoxaline-2-carboxalidene)-1,2-diaminocyclohexane and N,N'-bis(quinoxaline-2-carboxalidene)-1,2-diaminobenzene.The Schiff base ligands have been characterised by spectral and single crystal XRD studies.Theses ligands provide great structural diversity during complexation.Mn(II) and Ni(II) form octahedral with these Schiff bases,whereas Cu(II) forms both octahedral and tetrahedral complexes.Studies on the biological and Catalytic activity of the copper(ll) complexes are also presented in this thesis.

Diversity and antimicrobial activity of Lactic Acid Bacteria from the gut of marine fish Rastrelliger kanagurta against fish, shrimp and human pathogens

Emergence of antibiotic resistance among aquaculture pathogens has made it necessary to look into environment friendly, effective and sustainable methods such as probiotic and immunostimulants among others.. In the present study, LAB were isolated from the gut of fish species namely Rastrelliger kanagurta and analyzed for their antibacterial activity against various fish, shrimp and human pathogens. Different LAB species such as Lactobacillus plantarum, L. bulgaricus, L. brevis and L. viridiscens were encountered in the gut of R. kanagurta. Several strains showed good activity against fish, shrimp and human pathogens. LAB from the gut of such marine species may be developed as possible probiont for environment friendly health management of fresh water, estuarine and marine species currently exploited in aquaculture

Controls on development and diversity of Early Archean stromatolites

The ≈3,450-million-year-old Strelley Pool Formation in Western Australia contains a reef-like assembly of laminated sedimentary accretion structures (stromatolites) that have macroscale characteristics suggestive of biological influence. However, direct microscale evidence of biology—namely, organic microbial remains or biosedimentary fabrics—has to date eluded discovery in the extensively-recrystallized rocks. Recently-identified outcrops with relatively good textural preservation record microscale evidence of primary sedimentary processes, including some that indicate probable microbial mat formation. Furthermore, we find relict fabrics and organic layers that covary with stromatolite morphology, linking morphologic diversity to changes in sedimentation, seafloor mineral precipitation, and inferred microbial mat development. Thus, the most direct and compelling signatures of life in the Strelley Pool Formation are those observed at the microscopic scale. By examining spatiotemporal changes in microscale characteristics it is possible not only to recognize the presence of probable microbial mats during stromatolite development, but also to infer aspects of the biological inputs to stromatolite morphogenesis. The persistence of an inferred biological signal through changing environmental circumstances and stromatolite types indicates that benthic microbial populations adapted to shifting environmental conditions in early oceans.

Hay strewing, brush harvesting of seed and soil disturbance as tools for the enhancement of botanical diversity in grasslands

Since the middle of the last century agricultural intensification within Europe has led to a drastic decline in the extent of botanically diverse grasslands. Whilst measures to enhance the diversity of agriculturally-improved grasslands are in place, success has often been limited. One of the primary factors limiting success is the paucity of sources of propagules of desirable species in the surrounding landscape. The restoration of two contrasting grassland types lowland hay meadow and chalk grassland) was examined using a replicated block experiment to assess the effectiveness of two methods of seed application (hay strewing and brush harvesting) and two methods of pre-treatment disturbance (power harrowing and turf stripping). The resulting changes in botanical composition were monitored for 4 years. Seed addition by both methods resulted in significant temporal trends in plant species composition and increases in plant species richness, which were further enhanced by disturbance. Power harrowing increased the effectiveness of the seed addition treatments at the lowland hay meadow site. At the chalk grassland site a more severe disturbance created by turf stripping was used and shown to be preferable. Whilst both hay strewing and brush harvesting increased plant species richness, hay strewing was more effective at creating a sward similar to that of the donor site. Soil disturbance and seed application rate at the recipient site and timing of the hay cut at the donor site are all factors to be considered prior to the commencement of restoration management. (c) 2006 Elsevier Ltd. All rights reserved.

Population genetic diversity of the endemic Sardinian newt Euproctus platycephalus: implications for conservation

The Sardinian mountain newt Euproctus platycephalus, endemic to the island of Sardinia, (Italy), is considered a rare and threatened species and is classed as critically endangered by IUCN. It inhabits streams, small lakes and pools on the main mountain systems of the island. Threats from climatic and anthropogenic factors have raised concerns for the long-term survival of newt populations on the island. MtDNA sequencing was used to investigate the genetic population structure and phylogeography of this endemic species. Patterns of genetic variation were assessed by sequencing the complete Dloop region and part of the 12SrRNA, from 74 individuals representing four different populations. Analyses of molecular variance suggest that populations are significantly differentiated, and the distribution of haplotypes across the island shows strong geographical structuring. However, phylogenetic analyses also suggest that the Sardinian population consists of two distinct mtDNA groups, which may reflect ancient isolation and expansion events. Population structure, evolutionary history of the species and implications for the conservation of newt populations are discussed.

Functional benefits of predator species diversity depend on prey identity

1. Determining the functional significance of species diversity in natural enemy assemblages is a key step towards prediction of the likely impact of biodiversity loss on natural pest control processes. While the biological control literature contains examples in which increased natural enemy diversity hinders pest control, other studies have highlighted mechanisms where pest suppression is promoted by increased enemy diversity. 2. This study aimed to test whether increased predator species diversity results in higher rates of predation on two key, but contrasting, insect pest species commonly found in the rice ecosystems of south-east Asia. 3. Glasshouse experiments were undertaken in which four life stages of a planthopper (Nilaparvata lugens) and a moth (Marasmia patnalis) were caged with single or three-species combinations of generalist predators. 4. Generally, predation rates of the three-species assemblages exceeded expectation when attacking M. patnalis, but not when attacking N. lugens. In addition, a positive effect of increased predator species richness on overall predation rate was found with M. patnalis but not with N. lugens. 5. The results are consistent with theoretical predictions that morphological and behavioural differentiation among prey life stages promotes functional complementarity among predator species. This indicates that emergent species diversity effects in natural enemy assemblages are context dependent; they depend not only on the characteristics of the predators species, but on the identity of the species on which they prey.

The distribution of species diversity across a flora's component lineages: dating the Cape's 'relicts'

The Cape Floristic Region is exceptionally species-rich both for its area and latitude, and this diversity is highly unevenly distributed among genera. The modern flora is hypothesized to result largely from recent (post-Oligocene) speciation, and it has long been speculated that particular species-poor lineages pre-date this burst of speciation. Here, we employ molecular phylogenetic data in combination with fossil calibrations to estimate the minimum duration of Cape occupation by 14 unrelated putative relicts. Estimates vary widely between lineages (7-101 Myr ago), and when compared with the estimated timing of onset of the modern flora's radiation, it is clear that many, but possibly not all, of these lineages pre-date its establishment. Statistical comparisons of diversities with lineage age show that low species diversity of many of the putative relicts results from a lower rate of diversification than in dated Cape radiations. In other putative relicts, however, we cannot reject the possibility that they diversify at the same underlying rate as the radiations, but have been present in the Cape for insufficient time to accumulate higher diversity. Although the extremes in diversity of currently dated Cape lineages fall outside expectations under a underlying diversification rate, sampling of all Cape lineages would be required to reject this null hypothesis.

Low genetic diversity in a marine nature reserve: re-evaluating diversity criteria in reserve design

Little consideration has been given to the genetic composition of populations associated with marine reserves, as reserve designation is generally to protect specific species, communities or habitats. Nevertheless, it is important to conserve genetic diversity since it provides the raw material for the maintenance of species diversity over longer, evolutionary time-scales and may also confer the basis for adaptation to environmental change. Many current marine reserves are small in size and isolated to some degree (e.g. sea loughs and offshore islands). While such features enable easier management, they may have important implications for the genetic structure of protected populations, the ability of populations to recover from local catastrophes and the potential for marine reserves to act as sources of propagules for surrounding areas. Here, we present a case study demonstrating genetic differentiation, isolation, inbreeding and reduced genetic diversity in populations of the dogwhelk Nucella lapillus in Lough Hyne Marine Nature Reserve (an isolated sea lough in southern Ireland), compared with populations on the local adjacent open coast and populations in England, Wales and France. Our study demonstrates that this sea lough is isolated from open coast populations, and highlights that there may be long-term genetic consequences of selecting reserves on the basis of isolation and ease of protection.

Application of molecular biological methods for studying probiotics and the gut flora

Increasingly, the microbiological scientific community is relying on molecular biology to define the complexity of the gut flora and to distinguish one organism from the next. This is particularly pertinent in the field of probiotics, and probiotic therapy, where identifying probiotics from the commensal flora is often warranted. Current techniques, including genetic fingerprinting, gene sequencing, oligonucleotide probes and specific primer selection, discriminate closely related bacteria with varying degrees of success. Additional molecular methods being employed to determine the constituents of complex microbiota in this area of research are community analysis, denaturing gradient gel electrophoresis (DGGE)/temperature gradient gel electrophoresis (TGGE), fluorescent in situ hybridisation (FISH) and probe grids. Certain approaches enable specific aetiological agents to be monitored, whereas others allow the effects of dietary intervention on bacterial populations to be studied. Other approaches demonstrate diversity, but may not always enable quantification of the population. At the heart of current molecular methods is sequence information gathered from culturable organisms. However, the diversity and novelty identified when applying these methods to the gut microflora demonstrates how little is known about this ecosystem. Of greater concern is the inherent bias associated with some molecular methods. As we understand more of the complexity and dynamics of this diverse microbiota we will be in a position to develop more robust molecular-based technologies to examine it. In addition to identification of the microbiota and discrimination of probiotic strains from commensal organisms, the future of molecular biology in the field of probiotics and the gut flora will, no doubt, stretch to investigations of functionality and activity of the microflora, and/or specific fractions. The quest will be to demonstrate the roles of probiotic strains in vivo and not simply their presence or absence.

Structural diversity of sainfoin (Onobrychis viciifolia) tannins

Tannins are oligomeric and polymeric polyphenols that are produced by many plants. The study of their biological activities is of interest because they can generate valuable nutritional, veterinary and environmental effects in ruminant livestock production [1]. Isolated tannin fractions from sainfoin (Onobrychis viciifolia), which is potentially a very useful animal feed, were characterised by MALDI-TOF MS and thiolytic degradation with benzyl mercaptan. Condensed tannins were analysed and characterised in more than different 40 sainfoin varieties to provide guidelines for future plant breeding programmes. Several different techniques were used to study these complex tannin mixtures.

Multiple diversity measures to identify complementary conservation areas for the Baja California peninsular cacti

The Baja California Peninsula is home to 85 species of cacti, of which 54 are endemic, highlighting its importance as a cactus diverse region within Mexico. Many species are under threat due to collection pressure and habitat loss, but ensuring maximal protection of cacti species requires a better understanding of diversity patterns. We assessed species richness, endemism, and phylogenetic and morphological diversity using herbarium records and a molecular phylogeny for 82 species of cacti found in the peninsula. The four diversity measures were estimated for the existing nature reserve network and for 314 hexagrids of 726 km2. Using the hexagrid data, we surveyed our results for areas that best complement the current protected cacti diversity in the Baja California Peninsula. Currently, the natural reserve network in Baja shelters an important amount of the cacti diversity (74% of the species, 85.9% of the phylogenetic diversity, 76% of endemics and all the growth forms). While species richness produced several solutions to complement the diversity protected, by identifying priority species (endemic species with high contribution to overall PD) one best solution is reported. Three areas (San Matías, Magdalena and Margarita Islands and El Triunfo), selected using species richness, PD and endemism, best complement the diversity currently protected, increasing species richness to 89%, PD to 94% and endemism to 89%, and should be considered in future conservation plans. Two of these areas could be included within nature reserves already established.