One-year survey of a single Micronesian reef reveals extraordinarily rich diversity of Symbiodinium types in soritid foraminifera

Recent molecular studies of symbiotic dinoflagellates (genus Symbiodinium) from a wide array of invertebrate hosts have revealed exceptional fine-scale symbiont diversity whose distribution among hosts, regions and environments exhibits significant biogeographic, ecological and evolutionary patterns. Here, similar molecular approaches using the internal transcribed spacer-2 (ITS-2) region were applied to investigate cryptic diversity in Symbiodinium inhabiting soritid foraminifera. Approximately 1,000 soritid specimens were collected and examined during a 12-month period over a 40m depth gradient from a single reef in Guam, Micronesia. Out of 61 ITS-2 types distinguished, 46 were novel. Most types found are specific for soritid hosts, except for three types (C1, C15 and C19) that are common in metazoan hosts. The distribution of these symbionts was compared with the phylotype of their foraminiferal hosts, based on soritid small subunit ribosomal DNA sequences, and three new phylotypes of soritid hosts were identified based on these sequences. Phylogenetic analyses of 645 host-symbiont pairings revealed that most Symbiodinium types associated specifically with a particular foraminiferal host genus or species, and that the genetic diversity of these symbiont types was positively correlated with the genetic diversity found within each of the three host genera. Compared to previous molecular studies of Symbiodinium from other locations worldwide, the diversity reported here is exceptional and suggests that Micronesian coral reefs are home to a remarkably large Symbiodinium assemblag

Generalist dinoflagellate endosymbionts and host genotype diversity detected from mesophotic (67-100 m depths) coral Leptoseris

<p>Abstract</p> <p>Background</p> <p>Mesophotic corals (light-dependent corals in the deepest half of the photic zone at depths of 30 - 150 m) provide a unique opportunity to study the limits of the interactions between corals and endosymbiotic dinoflagellates in the genus <it>Symbiodinium</it>. We sampled <it>Leptoseris </it>spp. in Hawaii via manned submersibles across a depth range of 67 - 100 m. Both the host and <it>Symbiodinium </it>communities were genotyped, using a non-coding region of the mitochondrial ND5 intron (NAD5) and the nuclear ribosomal internal transcribed spacer region 2 (ITS2), respectively.</p> <p>Results</p> <p>Coral colonies harbored endosymbiotic communities dominated by previously identified shallow water <it>Symbiodinium </it>ITS2 types (C1_ AF333515, C1c_ AY239364, C27_ AY239379, and C1b_ AY239363) and exhibited genetic variability at mitochondrial NAD5.</p> <p>Conclusion</p> <p>This is one of the first studies to examine genetic diversity in corals and their endosymbiotic dinoflagellates sampled at the limits of the depth and light gradients for hermatypic corals. The results reveal that these corals associate with generalist endosymbiont types commonly found in shallow water corals and implies that the composition of the <it>Symbiodinium </it>community (based on ITS2) alone is not responsible for the dominance and broad depth distribution of <it>Leptoseris </it>spp. The level of genetic diversity detected in the coral NAD5 suggests that there is undescribed taxonomic diversity in the genus <it>Leptoseris </it>from Hawaii.</p

Rendimiento de la canal y ganancia de peso en vacas de descarte con inducción del anestro por vías quirúrgica versus mecánica

Orquera, M.L.; Pochon, D.O.; Flores, S.; Konrad, J.L.; Crudeli, G.A.: Rendimiento de la canal y ganancia de peso en vacas de descarte con inducción de anestro por vías quirúrgica versus mecánica. Rev. vet. 22: 1, 64–67, 2011. Palabras clave: vaca descarte, dispositivo intrauterino, castración quirúrgica, ganancia de peso, performance de canal

Acción tóxica del tetratiomolibdato de amonio sobre el tejido testicular en ratas

La acción tóxica del molibdeno, por sí mismo o por su interacción con el metabolismo del cobre, podría ocasionar trastornos sobre diversos tejidos. Con el fin de provocar una deficiencia secundaria de cobre, se procedió al agregado de tetratiomolibdato de amonio (TTMo) en la dieta de ratas, para evaluar sus efectos sobre la función reproductiva. En rumiantes, la toxicidad del Mo es provocada por la formación de tetratiomolibdatos por la microflora ruminal. Con este producto sintetizado in vitro, se pudo reproducir la enfermedad en ratas que, como el resto de los monogástricos, son particularmente resistentes a la intoxicación natural del Mo por carecer del ambiente digestivo adecuado para dicha transformación. Para lograr el objetivo propuesto, se valoró la respuesta de la testosterona tras el estímulo de gonadorrelinas (GnRH) y mediante estudios anatomohistopatológicos se determinó la integridad estructural del tejido testicular. Se utilizaron 40 ratas de sexo macho de la cepa Wistar, de 3 meses de edad; los grupos tratados recibieron durante 120 días dosis de 3 mg de TTMo/100 ml de agua de bebida. En este ensayo de molibdenosis experimental se logró una sintomatología clínica y bioquímica compatible con una deficiencia secundaria de cobre. Las diferencias entre grupos tratados y testigos en la respuesta de testosterona después de la inyección de GnRH, fueron significativas, indicando una función endocrina comprometida. Los ejemplares tratados revelaron disminución del tamaño testicular, túbulos seminíferos con fenómenos degenerativos del epitelio germinal, necrosis y desaparición de espermátides y espermatozoides. Algunos testículos presentaban únicamente espermatogonias y células de Sertoli con fenómenos de vacuolización citoplasmática, picnosis nuclear ycélulas gigantes fagocíticas multinucleadas. Las lesiones en el tejido intersticial se caracterizaron por fibrosis leve y depleción de células intersticiales de Leydig

Identifying and Characterizing Alternative Molecular Markers for the Symbiotic and Free-Living Dinoflagellate Genus Symbiodinium

Dinoflagellates in the genus Symbiodinium are best known as endosymbionts of corals and other invertebrate as well as protist hosts, but also exist free-living in coastal environments. Despite their importance in marine ecosystems, less than 10 loci have been used to explore phylogenetic relationships in this group, and only the multi-copy nuclear ribosomal Internal Transcribed Spacer (ITS) regions 1 and 2 have been used to characterize fine-scale genetic diversity within the nine clades (A–I) that comprise the genus. Here, we describe a three-step molecular approach focused on 1) identifying new candidate genes for phylogenetic analysis of Symbiodinium spp., 2) characterizing the phylogenetic relationship of these candidate genes from DNA samples spanning eight Symbiodinium clades (A–H), and 3) conducting in-depth phylogenetic analyses of candidate genes displaying genetic divergences equal or higher than those within the ITS-2 of Symbiodinium clade C. To this end, we used bioinformatics tools and reciprocal comparisons to identify homologous genes from 55,551 cDNA sequences representing two Symbiodinium and six additional dinoflagellate EST libraries. Of the 84 candidate genes identified, 7 Symbiodinium genes (elf2, coI, coIII, cob, calmodulin, rad24, and actin) were characterized by sequencing 23 DNA samples spanning eight Symbiodinium clades (A–H). Four genes displaying higher rates of genetic divergences than ITS-2 within clade C were selected for in-depth phylogenetic analyses, which revealed that calmodulin has limited taxonomic utility but that coI, rad24, and actin behave predictably with respect to Symbiodinium lineage C and are potential candidates as new markers for this group. The approach for targeting candidate genes described here can serve as a model for future studies aimed at identifying and testing new phylogenetically informative genes for taxa where transcriptomic and genomics data are available

From Parent to Gamete: Vertical Transmission of Symbiodinium (Dinophyceae) ITS2 Sequence Assemblages in the Reef Building Coral Montipora capitata

Parental effects are ubiquitous in nature and in many organisms play a particularly critical role in the transfer of symbionts across generations; however, their influence and relative importance in the marine environment has rarely been considered. Coral reefs are biologically diverse and productive marine ecosystems, whose success is framed by symbiosis between reef-building corals and unicellular dinoflagellates in the genus Symbiodinium. Many corals produce aposymbiotic larvae that are infected by Symbiodinium from the environment (horizontal transmission), which allows for the acquisition of new endosymbionts (different from their parents) each generation. In the remaining species, Symbiodinium are transmitted directly from parent to offspring via eggs (vertical transmission), a mechanism that perpetuates the relationship between some or all of the Symbiodinium diversity found in the parent through multiple generations. Here we examine vertical transmission in the Hawaiian coral Montipora capitata by comparing the Symbiodinium ITS2 sequence assemblages in parent colonies and the eggs they produce. Parental effects on sequence assemblages in eggs are explored in the context of the coral genotype, colony morphology, and the environment of parent colonies. Our results indicate that ITS2 sequence assemblages in eggs are generally similar to their parents, and patterns in parental assemblages are different, and reflect environmental conditions, but not colony morphology or coral genotype. We conclude that eggs released by parent colonies during mass spawning events are seeded with different ITS2 sequence assemblages, which encompass phylogenetic variability that may have profound implications for the development, settlement and survival of coral offspring

Influencia de la raza, estación del año y etapa de lactación sobre el contenido mineral de leche de búfalas

El objetivo de este estudio fue determinar la composición mineral de la leche de búfala producida en la Provincia de Corrientes, Argentina, así como investigar variaciones atribuibles al estadio de lactación, época del año y raza. Se trabajó con leche de 25 búfalas de razas Murrah, Mediterránea, Jafarabadi y mestizas ½ Murrah x ½ Mediterránea, de segunda a séptima lactación, durante 19 meses, totalizando 105 muestras. Los animales pertenecían a un tambo localizado en una región de clima subtropical húmedo, con precipitaciones anuales de 1.690 mm y temperatura media anual de 22°C. Se obtuvieron valores medios para Ca (1,12 ± 0,40 g.kg–1), P (0,99 ± 0,32 g.kg–1), Mg (0,08 ± 0,02 g.kg–1), K (0,92 ± 0,25 g.kg–1), Na (0,35 ± 0,11 g.kg–1), Cu (0,35 ± 0,16 mg.kg–1), Mn (0,27 ± 0,10 mg.kg–1), Zn (4,10 ± 1,40 mg.kg–1) y Fe (1,61 ± 0,61 mg.kg–1). Estos parámetros no revelaron diferencias significativas atribuibles a la raza de los animales con excepción del Mg. La época del año afectó la composición de los minerales, con excepción de Mg y Zn. Las etapas de lactación influenciaron sobre los valores de Ca, P, K y Cu. Los resultados obtenidos indican que el contenido mineral en leche de búfalas resulta considerablemente influenciado por factores regionales

Variation in Symbiodinium ITS2 Sequence Assemblages among Coral Colonies

Endosymbiotic dinoflagellates in the genus Symbiodinium are fundamentally important to the biology of scleractinian corals, as well as to a variety of other marine organisms. The genus Symbiodinium is genetically and functionally diverse and the taxonomic nature of the union between Symbiodinium and corals is implicated as a key trait determining the environmental tolerance of the symbiosis. Surprisingly, the question of how Symbiodinium diversity partitions within a species across spatial scales of meters to kilometers has received little attention, but is important to understanding the intrinsic biological scope of a given coral population and adaptations to the local environment. Here we address this gap by describing the Symbiodinium ITS2 sequence assemblages recovered from colonies of the reef building coral Montipora capitata sampled across Kāne'ohe Bay, Hawai'i. A total of 52 corals were sampled in a nested design of Coral Colony(Site(Region)) reflecting spatial scales of meters to kilometers. A diversity of Symbiodinium ITS2 sequences was recovered with the majority of variance partitioning at the level of the Coral Colony. To confirm this result, the Symbiodinium ITS2 sequence diversity in six M. capitata colonies were analyzed in much greater depth with 35 to 55 clones per colony. The ITS2 sequences and quantitative composition recovered from these colonies varied significantly, indicating that each coral hosted a different assemblage of Symbiodinium. The diversity of Symbiodinium ITS2 sequence assemblages retrieved from individual colonies of M. capitata here highlights the problems inherent in interpreting multi-copy and intra-genomically variable molecular markers, and serves as a context for discussing the utility and biological relevance of assigning species names based on Symbiodinium ITS2 genotyping

The plant specific CDKB1-CYCB1 complex mediates homologous recombination repair in Arabidopsis

Upon DNA damage, cyclin-dependent kinases (CDKs) are typically inhibited to block cell division. In many organisms, however, it has been found that CDK activity is required for DNA repair, especially for homology-dependent repair (HR), resulting in the conundrum how mitotic arrest and repair can be reconciled. Here, we show that Arabidopsis thaliana solves this dilemma by a division of labor strategy. We identify the plant-specific B1-type CDKs (CDKB1s) and the class of B1-type cyclins (CYCB1s) as major regulators of HR in plants. We find that RADIATION SENSITIVE 51 (RAD51), a core mediator of HR, is a substrate of CDKB1-CYCB1 complexes. Conversely, mutants in CDKB1 and CYCB1 fail to recruit RAD51 to damaged DNA. CYCB1; 1 is specifically activated after DNA damage and we show that this activation is directly controlled by SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1), a transcription factor that acts similarly to p53 in animals. Thus, while the major mitotic cell-cycle activity is blocked after DNA damage, CDKB1-CYCB1 complexes are specifically activated to mediate HR