Influence of lighting environment on social preferences in sticklebacks from two different photic habitats. II. Shoaling and mate preferences of lab-bred fishes

Different environmental conditions may lead to diverse morphological, behavioral, and physiological adaptations of different populations of the same species. Lighting conditions, for example, vary vastly especially between aquatic habitats, and have been shown to elicit adaptations. The availability of short-wave ultraviolet (UV) light is especially fluctuating, as UV wavelengths are attenuated strongly depending on water properties. The island of North Uist, Scotland, comprises 2 differential habitat types, tea-stained and clear-water lakes, varying considerably in UV transmission. In previous studies, wild-caught 3-spined stickleback Gasterosteus aculeatus populations (3 populations of each habitat type) were tested with respect to their shoaling and mate preferences for fish viewed under UV-present and UV-absent conditions. The results revealed a habitat-dependent preference of UV cues during shoal choice (tea-stained populations: preference for UV-absent condition in tea-stained water; clear-water populations: no preference in clear-water) but an overall preference for UV-present conditions during mate choice. To assess genetic influences on these behavioral patterns, similar experiments were conducted with lab-bred F1-generations of the same stickleback populations that were raised in a common environment (i.e. standardized clear-water conditions). Offspring of sticklebacks from tea-stained lakes tended to prefer shoals viewed under UV-absent conditions (only in tea-stained water), while sticklebacks from clear-water lakes showed a significant preference for the shoal viewed under UV-present conditions in clear-water but not in tea-stained water. Mate-preference experiments demonstrated that females from the tea-stained lakes significantly preferred and females from the clear-water lakes preferred by trend the male viewed under UV-present conditions in the clear-water treatment. The results for both shoaling- and mate-preference tests were largely similar for wild-caught and lab-bred sticklebacks, thus hinting at a genetic basis for the preference patterns.     

Arabinogalactan Glycosyltransferases Target to a Unique Subcellular Compartment That May Function in Unconventional Secretion in Plants

We report that fluorescently tagged arabinogalactan glycosyltransferases target not only the Golgi apparatus but also uncharacterized smaller compartments when transiently expressed in Nicotiana benthamiana. Approximately 80% of AtGALT31A [Arabidopsis thaliana galactosyltransferase from family 31 (At1g32930)] was found in the small compartments, of which, 45 and 40% of AtGALT29A [Arabidopsis thaliana galactosyltransferase from family 29 (At1g08280)] and AtGlcAT14A [Arabidopsis thaliana glucuronosyltransferase from family 14 (At5g39990)] colocalized with AtGALT31A, respectively; in contrast, N‐glycosylation enzymes rarely colocalized (3–18%), implicating a role of the small compartments in a part of arabinogalactan (O‐glycan) biosynthesis rather than N‐glycan processing. The dual localization of AtGALT31A was also observed for fluorescently tagged AtGALT31A stably expressed in an Arabidopsis atgalt31a mutant background. Further, site‐directed mutagenesis of a phosphorylation site of AtGALT29A (Y144) increased the frequency of the protein being targeted to the AtGALT31A‐localized small compartments, suggesting a role of Y144 in subcellular targeting. The AtGALT31A localized to the small compartments were colocalized with neither SYP61 (syntaxin of plants 61), a marker for trans‐Golgi network (TGN), nor FM4‐64‐stained endosomes. However, 41% colocalized with EXO70E2 (Arabidopsis thaliana exocyst protein Exo70 homolog 2), a marker for exocyst‐positive organelles, and least affected by Brefeldin A and Wortmannin. Taken together, AtGALT31A localized to small compartments that are distinct from the Golgi apparatus, the SYP61‐localized TGN, FM4‐64‐stained endosomes and Wortmannin‐vacuolated prevacuolar compartments, but may be part of an unconventional protein secretory pathway represented by EXO70E2 in plants.      

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

Ribosomal 16S rRNA gene pyrosequencing was used to explore whether the genetically modified (GM) Bt-maize hybrid MON 89034 × MON 88017, expressing three insecticidal recombinant Cry proteins of Bacillus thuringiensis, would alter the rhizosphere bacterial community. Fine roots of field cultivated Bt-maize and three conventional maize varieties were analyzed together with coarse roots of the Bt-maize. A total of 547 000 sequences were obtained. Library coverage was 100% at the phylum and 99.8% at the genus rank. Although cluster analyses based on relative abundances indicated no differences at higher taxonomic ranks, genera abundances pointed to variety specific differences. Genera-based clustering depended solely on the 49 most dominant genera while the remaining 461 rare genera followed a different selection. A total of 91 genera responded significantly to the different root environments. As a benefit of pyrosequencing, 79 responsive genera were identified that might have been overlooked with conventional cloning sequencing approaches owing to their rareness. There was no indication of bacterial alterations in the rhizosphere of the Bt-maize beyond differences found between conventional varieties. B. thuringiensis-like phylotypes were present at low abundance (0.1% of Bacteria) suggesting possible occurrence of natural Cry proteins in the rhizospheres. Although some genera indicated potential phytopathogenic bacteria in the rhizosphere, their abundances were not significantly different between conventional varieties and Bt-maize. With an unprecedented sensitivity this study indicates that the rhizosphere bacterial community of a GM maize did not respond abnormally to the presence of three insecticidal proteins in the root tissue.     

Changes in the photosynthetic apparatus of diatoms in response to low and high light intensities

The centric diatom Cyclotella cryptica and two strains of the pennate diatom Phaeodactylum tricornutum were grown under low and high light intensities (300 lux and 3,000 lux) over 4-6 weeks. Growth was monitored by repetitive cell count. The culture media were replaced weekly to avoid morphological and biochemical alterations caused by nutrient depletion. The ultrastructure of the cells was examined by transmission electron microscopy. Alterations in the light-harvesting antenna systems were investigated by Western immunoblotting. Both diatoms reduced the plastid area, i.e. decreased the amount of thylakoid lamellae, under high light intensity. The thylakoids still ran in groups of three with parallel orientation within the chloroplasts. The girdle band lamellae were not affected. The amounts of storage compounds and vacuoles increased. SDS-PAGE of total cell protein followed by Western immunoblotting with antisera directed against subunits of the light-harvesting antenna systems of C. cryptica (cc-antiserum) and the cryptophyte Cryptomonas maculata (cmac-antiserum) revealed that both diatoms reduced the amount of antenna polypeptides under increased light intensity. The cc-antiserum immunodecorated two bands with relative molecular masses (Mr) of 18,000 and 22,000 in C. cryptica. Both decreased under high light conditions to 67.2 +/- 6.1%. Five to seven bands in the Mr range of 14,000-27,000 were recognized in P. tricornutum. They decreased to 83 +/- 5.3%. Furthermore, the immunolabeling pattern for both strains differed under the two light regimes. The cmac-antiserum immunodecorated two polypeptides with Mr of 24,000 and 23,000 in C. cryptica, while both strains of P. tricornutum had five polypeptides in the Mr range of 14,000-24,000 that showed some differences in staining intensities between the two strains and in response to the light intensity applied.     

In-depth proteomic analyses of <Emphasis Type="Italic">Haliotis laevigata</Emphasis> (greenlip abalone) nacre and prismatic organic shell matrix

Background

The shells of various Haliotis species have served as models of invertebrate biomineralization and physical shell properties for more than 20 years. A focus of this research has been the nacreous inner layer of the shell with its conspicuous arrangement of aragonite platelets, resembling in cross-section a brick-and-mortar wall. In comparison, the outer, less stable, calcitic prismatic layer has received much less attention. One of the first molluscan shell proteins to be characterized at the molecular level was Lustrin A, a component of the nacreous organic matrix of Haliotis rufescens. This was soon followed by the C-type lectin perlucin and the growth factor-binding perlustrin, both isolated from H. laevigata nacre, and the crystal growth-modulating AP7 and AP24, isolated from H. rufescens nacre. Mass spectrometry-based proteomics was subsequently applied to to Haliotis biomineralization research with the analysis of the H. asinina shell matrix and yielded 14 different shell-associated proteins. That study was the most comprehensive for a Haliotis species to date.

Methods

The shell proteomes of nacre and prismatic layer of the marine gastropod Haliotis laevigata were analyzed combining mass spectrometry-based proteomics and next generation sequencing.

Results

We identified 297 proteins from the nacreous shell layer and 350 proteins from the prismatic shell layer from the green lip abalone H. laevigata. Considering the overlap between the two sets we identified a total of 448 proteins. Fifty-one nacre proteins and 43 prismatic layer proteins were defined as major proteins based on their abundance at more than 0.2% of the total. The remaining proteins occurred at low abundance and may not play any significant role in shell fabrication. The overlap of major proteins between the two shell layers was 17, amounting to a total of 77 major proteins.

Conclusions

The H. laevigata shell proteome shares moderate sequence similarity at the protein level with other gastropod, bivalve and more distantly related invertebrate biomineralising proteomes. Features conserved in H. laevigata and other molluscan shell proteomes include short repetitive sequences of low complexity predicted to lack intrinsic three-dimensional structure, and domains such as tyrosinase, chitin-binding, and carbonic anhydrase. This catalogue of H. laevigata shell proteins represents the most comprehensive for a haliotid and should support future efforts to elucidate the molecular mechanisms of shell assembly.

     

Where did Mikrotia magna originate? Drawing ecogeographical inferences from body mass reconstructions

Terre Rosse deposits (upper Miocene; Gargano, Italy) have provided fossil remains of an insular fauna among which the genus Mikrotia (Rodentia) stands out. Several paleobiological studies have already been conducted on this genus, but its body mass has not yet been calculated accurately. The aim of the present work is to reconstruct Mikrotia magna's weight, a paramount aspect of organismal biology, especially on islands where mammals modify their size, becoming giants or dwarfs (‘island rule’). Our analysis using postcranial elements (femora and humeri) predicts weights ranging from 1300 g to 1900 g (old and young populations, respectively). The presence of a large number of micromammals on the Gargano paleo-island suggests a high interspecific competition for species of the same ecological guild (Prolagus or cricetids were direct competitors of Mikrotia), which may lead to only moderate gigantism, or even body mass reductions in small mammals, following Palkovacs's model. This contrasts with the huge weight of M. magna inferred in this study. In this regard, stratigraphic and taxonomic studies suggest that M. magna was an immigrant from a neighboring island, indicating that this species originated and achieved its enormous size under other selective pressures. A native island with a lower number of competitors, and therefore with less resource limitation than Terre Rosse, might be the principal explanation for such a degree of gigantism.     

Endophytic fungi as biocontrol agents: elucidating mechanisms in disease suppression

ABSTRACT

Background

Fungal endophytes occur ubiquitously in plants and are being increasingly studied for their ability to support plant health and protect the host from diseases. Using endophytes in disease control provides potential advantages compared to other biocontrol agents since they colonise the plant internally and thereby stay protected from environmental stresses and fluctuations. A thorough understanding of their mechanisms is required in their mutualistic association with plants; both to optimise their efficacy and for registration as plant protection products.     

Intestinal Microbiota and Microbial Metabolites Are Changed in a Pig Model Fed a High-Fat/Low-Fiber or a Low-Fat/High-Fiber Diet

The intestinal microbiota and its metabolites appear to be an important factor for gastrointestinal function and health. However, research is still needed to further elaborate potential relationships between nutrition, gut microbiota and host’s health by means of a suitable animal model. The present study examined the effect of two different diets on microbial composition and activity by using the pig as a model for humans. Eight pigs were equally allotted to two treatments, either fed a low-fat/high-fiber (LF), or a high-fat/low-fiber (HF) diet for 7 weeks. Feces were sampled at day 7 of every experimental week. Diet effects on fecal microbiota were assessed using quantitative real-time PCR, DNA fingerprinting and metaproteomics. Furthermore, fecal short-chain fatty acid (SCFA) profiles and ammonia concentrations were determined. Gene copy numbers of lactobacilli, bifidobacteria (P<0.001) and Faecalibacterium prausnitzii (P<0.05) were higher in the LF pigs, while Enterobacteriaceae were more abundant in the HF pigs (P<0.001). Higher numbers of proteins affiliated to Enterobacteriaceae were also present in the HF samples. Proteins for polysaccharide breakdown did almost exclusively originate from Prevotellaceae. Total and individual fecal SCFA concentrations were higher for pigs of the LF treatment (P<0.05), whereas fecal ammonia concentrations did not differ between treatments (P>0.05). Results provide evidence that beginning from the start of the experiment, the LF diet stimulated beneficial bacteria and SCFA production, especially butyrate (P<0.05), while the HF diet fostered those bacterial groups which have been associated with a negative impact on health conditions. These findings correspond to results in humans and might strengthen the hypothesis that the response of the porcine gut microbiota to a specific dietary modulation is in support of using the pig as suitable animal model for humans to assess diet-gut-microbiota interactions.Data are available via ProteomeXchange with identifier PXD003447.     

Identification and structural characterization of further DNA elements in the potato and pepper genomes homologous to the transposable element-like insertion Tst1

Summary The molecular cloning and nucleotide sequence of elements from potato and pepper that are related to the recently identified Tst1 element are described. Sequence analysis reveals considerable conservation of sequences internal to both the Tst1 element and two of the related elements identified here. In six potato clones analysed, the II by inverted repeat first identified in the Tst1 element is conserved. Several of the elements are flanked by an 8 by direct repeat. DNA fragments which were amplified from several pepper genomes by polymerase chain reaction (PCR) amplification using the inverted repeat as sequence primers also display considerable conservation of sequences internal to the Tst1 element. These data further support the possibility that Tst1 is a non-autonomous transposable element and that Tst1 might be the first example of a transposable element which occurs in several genera of solanaceous plants.