Intraspecific variability in the response of bloom-forming marine microalgae to changed climate conditions

Phytoplankton populations can display high levels of genetic diversity that, when reflected by phenotypic variability, may stabilize a species response to environmental changes. We studied the effects of increased temperature and CO(2) availability as predicted consequences of global change, on 16 genetically different isolates of the diatom Skeletonema marinoi from the Adriatic Sea and the Skagerrak (North Sea), and on eight strains of the PST (paralytic shellfish toxin)-producing dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Maximum growth rates were estimated in batch cultures of acclimated isolates grown for five to 10 generations in a factorial design at 20 and 24°C, and present day and next century applied atmospheric pCO(2), respectively. In both species, individual strains were affected in different ways by increased temperature and pCO(2). The strongest response variability, buffering overall effects, was detected among Adriatic S. marinoi strains. Skagerrak strains showed a more uniform response, particularly to increased temperature, with an overall positive effect on growth. Increased temperature also caused a general growth stimulation in A. ostenfeldii, despite notable variability in strain-specific response patterns. Our data revealed a significant relationship between strain-specific growth rates and the impact of pCO(2) on growth-slow growing cultures were generally positively affected, while fast growing cultures showed no or negative responses to increased pCO(2). Toxin composition of A. ostenfeldii was consistently altered by elevated temperature and increased CO(2) supply in the tested strains, resulting in overall promotion of saxitoxin production by both treatments. Our findings suggest that phenotypic variability within populations plays an important role in the adaptation of phytoplankton to changing environments, potentially attenuating short-term effects and forming the basis for selection. In particular, A. ostenfeldii blooms may expand and increase in toxicity under increased water temperature and atmospheric pCO(2) conditions, with potentially severe consequences for the coastal ecosystem.     

Relative apparent synapomorphy analysis (RASA). I: The statistical measurement of phylogenetic signal

We have developed a new approach to the measurement of phylogenetic signal in character state matrices called relative apparent synapomorphy analysis (RASA). RASA provides a deterministic, statistical measure of natural cladistic hierarchy (phylogenetic signal) in character state matrices. The method works by determining whether a measure of the rate of increase of cladistic similarity among pairs of taxa as a function of phenetic similarity is greater than a null equiprobable rate of increase. Our investigation of the utility and limitations of RASA using simulated and bacteriophage T7 data sets indicates that the method has numerous advantages over existing measures of signal. A first advantage is computational efficiency. A second advantage is that RASA employs known methods of statistical inference, providing measurable sensitivity and power. The performance of RASA is examined under various conditions of branching evolution as the number of characters, character states per character, and mutations per branch length are varied. RASA appears to provide an unbiased and reliable measure of phylogenetic signal, and the general approach promises to be useful in the development of new techniques that should increase the rigor and reliability of phylogenetic estimates.      

RT-qPCR reveals opsin gene upregulation associated with age and sex in guppies (Poecilia reticulata) - a species with color-based sexual selection and 11 visual-opsin genes

Background  

PCR-based surveys have shown that guppies (Poecilia reticulata) have an unusually large visual-opsin gene repertoire. This has led to speculation that opsin duplication and divergence has enhanced the evolution of elaborate male coloration because it improves spectral sensitivity and/or discrimination in females. However, this conjecture on evolutionary connections between opsin repertoire, vision, mate choice, and male coloration was generated with little data on gene expression. Here, we used RT-qPCR to survey visual-opsin gene expression in the eyes of males, females, and juveniles in order to further understand color-based sexual selection from the perspective of the visual system.     

Genome Sequence of Lactobacillus crispatus ST1

Lactobacillus crispatus is a common member of the beneficial microbiota present in the vertebrate gastrointestinal and human genitourinary tracts. Here, we report the genome sequence of L. crispatus ST1, a chicken isolate displaying strong adherence to vaginal epithelial cells.Lactobacillus crispatus can persist in the vertebrate gastrointestinal tract and is among the most prevalent species of the Lactobacillus-dominated human vaginal microbiota (2, 9, 13, 14). It belongs to the so-called acidophilus group (3), which has attracted interest because some of its species are important factors in the production of fermented foods (12) and some can, at least transiently, colonize the human host (2, 9, 13, 14). Moreover, some specific strains, mainly L. acidophilus NCFM and L. johnsonii NCC 533, have received prominence as intestinal-health-promoting microbes (4). Although the genomes of seven members of the acidophilus complex have been sequenced to date (12), the genome sequences of L. crispatus and other predominant lactobacillar species in the urogenital flora have mostly remained obscure. Vaginal lactobacilli can have an important role in controlling the health of the host (2, 14). They can, for example, positively influence and stabilize the host''s vaginal microbiota via the production of compounds that are acidic or exert a direct inhibiting action toward pathogenic bacteria (2, 14). In addition to the antimicrobial compounds, the competitive exclusion of pathogens is another mechanism by which the host''s microbiota can be balanced (2). L. crispatus ST1 was originally isolated from the crop of a chicken, and PCR profiling of L. crispatus isolates has verified it to be an abundant colonizer of the chicken crop (6, 8). It also displays a strong protein-dependent adhesion to the epithelial cells of the human vagina and has been shown to inhibit the adhesion of avian pathogenic Escherichia coli (6, 7).The genome was sequenced (18× coverage) using a 454 pyrosequencer with GS FLX chemistry (Roche). The contig order was confirmed and gaps were filled by sequencing PCR fragments from the genomic DNA template using ABI 3730 and Big Dye chemistry (Applied Biosystems). Genomic data were processed using the Staden Package (11) and gsAssembler (Roche). Coding sequences (CDSs) were predicted using Glimmer3 (5) followed by manual curation of the start sites. The remaining intergenic regions were reanalyzed for missed CDSs by using BlastX (1). Annotation transfer was performed based on a BlastP search, followed by Blannotator analysis using default settings (http://ekhidna.biocenter.helsinki.fi/poxo/blannotator) and manual verification. Orthologous groups between the different lactobacillar proteomes were identified using OrthoMCL (10).The genome of L. crispatus ST1 consists of a single circular chromosome 2.04 Mbp in size, with an overall G+C content of 37%, without any plasmids. There are 64 tRNA genes, 4 rRNA operons, and 2 CRISPR loci. Out of the 2,024 predicted CDSs, a putative function was assigned to 77%, whereas 10% of the CDSs were annotated as conserved and 13% as novel. Based on the orthologous grouping, 302 (15%) of the CDSs encoded by ST1 have no detectable homologs in any of the Lactobacillus proteomes published to date.     

Lignification related enzymes in Picea abies suspension cultures

Activity of a number of enzymes related to lignin formation was measured in a Picea abies (L) Karsten suspension culture that is able to produce native-like lignin into the nutrient medium. This cell culture is an attractive model for studying lignin formation, as the process takes place independently of the complex macromolecular matrix of the native apoplast. Suspension culture proteins were fractionated into soluble cellular proteins, ionically and covalently bound cell wall proteins and nutrient medium proteins. The nutrient medium contained up to 5.3% of total coniferyl alcohol peroxidase (EC 1.11.1.7) activity and a significant NADH oxidase activity that is suggested to be responsible for hydrogen peroxide (H2O2) production. There also existed some malate dehydrogenase (EC 1.1.1.37) activity in the apoplast of suspension culture cells (in ionically and covalently bound cell wall protein fractions), possibly for the regeneration of NADH that is needed for peroxidase-catalysed H2O2 production. However, there is no proof of the existence of NADH in the apoplast. Nutrient medium peroxidases could be classified into acidic, slightly basic and highly basic isoenzyme groups by isoelectric focusing. Only acidic peroxidases were found in the covalently bound cell wall protein fraction. Several peroxidase isoenzymes across the whole pI range were detected in the protein fraction ionically bound to cell walls and in the soluble cellular protein fraction. One laccase-like isoenzyme with pI of approximately 8.5 was found in the nutrient medium that was able to form dehydrogenation polymer from coniferyl alcohol in the absence of H2O2. The total activity of this oxidase towards coniferyl alcohol was, however, several orders of magnitude smaller than that of peroxidases in vitro. According to 2D 1H-13C correlation NMR spectra, most of the abundant structural units of native lignin and released suspension culture lignin are present in the oxidase produced dehydrogenation polymer but in somewhat different amounts compared to peroxidase derived synthetic lignin preparations. A coniferin beta-glucosidase (EC 3.2.1.21) was observed to be secreted into the culture medium.     

Milk Fever Control Principles: A Review

Three main preventive principles against milk fever were evaluated in this literature review, and the efficacy of each principle was estimated from the results of controlled investigations. Oral calcium drenching around calving apparently has a mean efficacy of 50%–60% in terms of milk fever prevention as well as prevention of milk fever relapse after intravenous treatment with calcium solutions. However, some drenches have been shown to cause lesions in the forestomacs. When using the DCAD (dietary cation-anion difference) principle, feeding rations with a negative DCAD (measured as (Na + K) – (Cl + S)) significantly reduce the milk fever incidence. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a mean RR between 0.19 and 0.35 when rations with a negative versus positive DCAD are compared. The main drawback from the DCAD principle is a palatability problem. The principle of feeding rations low in calcium is highly efficient in milk fever prevention provided the calcium intake in the dry period is kept below 20 g per day. Calculating the relative risk (RR) of developing milk fever from controlled experiments results in a very low mean RR (between 0 and 0.20) (daily calcium intake below versus above 20 g/d). The main problem in implementing the low-Ca principle is difficulties in formulating rations sufficiently low in calcium when using commonly available feeds. The use of large doses of vitamin D metabolites and analogues for milk fever prevention is controversial. Due to toxicity problems and an almost total lack of recent studies on the subject this principle is not described in detail. A few management related issues were discussed briefly, and the following conclusions were made: It is important to supply the periparturient cow with sufficient magnesium to fulfil its needs, and to prevent the dry cows from being too fat. Available information on the influence of carbohydrate intake, and on the effect of the length of the dry period and prepartum milking, is at present insufficient to include these factors in control programmes.     

Low-temperature sensitivity and enhanced Bohr effect in red deer (Cervus elaphus) haemoglobin: a molecular adaptive strategy to life at high altitude and low temperature.

A study of the functional properties of haemoglobin from red deer (Cervus elaphus) whose habitat varies over a wide range of latitude, was performed. The oxygen-binding properties of the most common haemoglobin phenotype from the species living in Sardinia were examined with particular attention to the effect of pH, chloride, 2, 3-bisphosphoglycerate and temperature. Results indicate that red deer haemoglobin, like all haemoglobins from ruminants so far examined, is characterized by a low intrinsic oxygen affinity, with chloride being its main physiological modulator in vivo. The functional results and the low temperature sensitivity of the oxygen affinity are discussed in the light of the amino acid sequence of closely related ruminant haemoglobins.     

Risk of Infection with Leishmania spp. in the Canine Population in the Netherlands

The dog is the main reservoir of Leishmania infantum, the causative agent of visceral leishmaniasis (VL) in humans in Southern Europe. In order to identify the risk of dogs from a Leishmania non-endemic area traveling to a Leishmania -endemic area becoming infected and the risk of transmitting infection to humans in non-endemic areas an investigation was performed, in which the results of a questionnaire were combined with the results of a serologic survey.     

Releases of Norepinephrine and Dopamine in Ventriculocisternal Perfusions in Hepatectomized and Laparotomized Rats

Abstract: The completely hepatectomized rat has frequently been used as a model to study changes in the economy of norepinephrine (NE) and dopamine (DA) in hepatic coma. Hypothermia characteristically develops in hepatectomized rats and also occurs in patients in hepatic coma and is associated with improved survival in both. The aims of the present study were to measure both release and uptake of NE and release of DA in brain in warm (37°C) and cool (30–32°C) rats at 3–5 h after laparotomy or hepatectomy. Ventriculocisternal perfusions of the brain were performed on rats under basal conditions and during releases evoked by 40 m M K⁺. Basal releases of NE and DA and evoked release of DA were greater in the warm hepatectomized rats than in all other groups. In some studies, 10⁻⁵ M amitriptyline was added to the perfusates to assess whether neuronal uptake was changed after hepatectomy. Uptake of released NE was equally robust in cool hepatectomized as in cool laparotomized rats but could not be measured in warm hepatectomized rats because of amitriptyline toxicity in these rats. Decreases in NE and increases in DA content were found in most areas of the brain after perfusion. Increased releases of NE and DA may contribute to the pathogenesis of hepatic encephalopathy.