Coral reefs are deteriorating at an alarming rate mainly as a consequence of the emergence of coral diseases. The white plague disease (WPD) is the most prevalent coral disease in the southwestern Caribbean, affecting dozens of coral species. However, the identification of a single causal agent has proved problematic. This suggests more complex etiological scenarios involving alterations in the dynamic interaction between environmental factors, the coral immune system and the symbiotic microbial communities. Here we compare the microbiome of healthy and WPD-affected corals from the two reef-building species Diploria strigosa and Siderastrea siderea collected at the Tayrona National Park in the Caribbean of Colombia. Microbiomes were analyzed by combining culture-dependent methods and pyrosequencing of 16S ribosomal DNA (rDNA) V5-V6 hypervariable regions. A total of 20 410 classifiable 16S rDNA sequences reads were obtained including all samples. No significant differences in operational taxonomic unit diversity were found between healthy and affected tissues; however, a significant increase of Alphaproteobacteria and a concomitant decrease in the Beta-and Gammaproteobacteria was observed in WPD-affected corals of both species. Significant shifts were also observed in the orders Rhizobiales, Caulobacteriales, Burkholderiales, Rhodobacterales, Aleteromonadales and Xanthomonadales, although they were not consistent between the two coral species. These shifts in the microbiome structure of WPD-affected corals suggest a loss of community-mediated growth control mechanisms on bacterial populations specific for each holobiont system. The ISME Journal (2012) 6, 502-512; doi:10.1038/ismej.2011.123; published online 29 September 2011Subject Category: microbial population and community ecology Keywords: bacterial community; white plague disease; coral diseases; pyrosequencing; Diploria strigosa; Siderastrea siderea IntroductionCoral reefs posses an immense biodiversity comparable only to that of the tropical rain forest (Mulhall, 2009). The structural, physiological and ecological bases of reefs are the scleractinian corals. They are in symbiotic relationship with a variety of bacteria and archaea as well as with microalgae (zooxanthellae), which are mainly responsible for the corals' high contribution to primary productivity of coral reefs . Modifications in the structure and relative density of symbiotic microbial communities might have a critical role in the coral adaptation to rapid environmental changes (Reshef et al., 2006). In the last three decades, local and global deterioration of environmental conditions have dramatically compromised the health of corals, which consequently affected the entire coral reef ecosystem. (Harvell et al., 1999(Harvell et al., , 2007Wilkinson, 1999;Green and Bruckner, 2000;Gardner et al., 2003;Pandolfi et al., 2003;Lesser et al., 2007). Recent reports indicate that 58-70% of coral reefs worldwide are threatened by human activities, while more than 30% of the biota associated with Caribb...

We have developed defined genetic lines of the hydroid Hydractinia symbiolongicarpus and confirmed earlier results showing that allorecognition is controlled by a single chromosomal region within these lines. In a large backcross population, we detected recombinants that display a fusibility phenotype distinct from typical fusion and rejection. We show that this transitory fusion phenotype segregates in a fashion expected of a single Mendelian trait, establishing that the chromosomal interval contains at least two genes that interact to determine fusibility. Using bulked segregant analysis, we have identified amplified fragment length polymorphisms (AFLP) cosegregating with fusibility, used these markers to independently confirm linkage of the two loci, and constructed a 3.4-cM map of an invertebrate histocompatibility complex.T HE hydroid Hydractinia has a long been a favored quently applied a conventional incross/intercross/backcross analysis. Within these defined genetic lines, Hymodel in efforts to understand invertebrate allorecognition (von Hauenschild 1954(von Hauenschild , 1956 Mü ller 1964; dractinia allorecognition segregated as a one-locus trait with codominant expression of alleles, such that two Buss et al. 1984;Mü ller et al. 1987;Lange et al. 1989Lange et al. , 1992; Buss and Grosberg 1990; Shenk and Buss 1991; colonies fuse if they share at least one allele. Grosberg et al. 1996; Mokady and Buss 1996). Colonies, We here report the further development of these inwhich often encrust the shells of hermit crabs, grow by bred and congenic lines and confirm, with an expanded elongation and branching of stolons. When two or more population, that segregation of fusibility follows singlelarvae recruit to the same substratum, stolons of differlocus codominant Mendelian expectations. A fusibility ent colonies may eventually come into contact. Close phenotype first observed by von Hauenschild (1954, proximity of an approaching stolon induces the produc-1956), in which interacting colonies initially fuse only tion of a new stolon tip along the flank of the stolon to later separate, appeared at low frequencies in this being approached. If the two colonies are histocompaticross. We report a series of crosses that establish that ble, the two tips will first adhere, and then fuse, establishthe transitory fusion (TF) phenotype itself behaves as ing functional gastrovascular continuity and a permaa single Mendelian trait linked to the original allorecognent genetic chimera. In contrast, tips of incompatible nition locus. Moreover, we show that this TF phenotype colonies fail to adhere to one another, but instead swell is readily detected in only one of the two conventional with the migration of nematocysts, which discharge to fusion assays. Finally, we use bulked segregant analysis effect tissue damage.to identify molecular markers linked to the interval and The transmission genetics of allorecognition in Hyreport the use of these markers to construct a genetic dractinia were first addressed in the mid-19...

Homologues of the human major histocompatibility complex (MHC) HLA-A, -B, -E, -F, and -G loci are present in all the Catarrhini (Old World primates, apes, and humans), and some of their allelic lineages have survived several speciation events. Analysis of 26 MHC class I cDNAs from seven different genera of New World primates revealed that the Callitrichinae (tamarins and marmosets) are an exception to these rules of MHC stability. In gene trees of primate MHC class I genes, sequences from the Callitrichinae cluster in a genus-specific fashion, whereas in the other genera of New World primates, as in the Catarrhini, they cluster in a transgeneric way. The genus-specific clustering of the Callitrichinae cDNAs indicates that there is no orthology between MHC class I loci in genera of this phyletic group. Additionally, the Callitrichinae genera exhibit limited variability of their MHC class I genes, in contrast to the high variability displayed by all other primates. Each Callitrichinae genus, therefore, expresses its own set of MHC class I genes, suggesting that an unusually high rate of turnover of loci occurs in this subfamily. The limited variability of MHC class I genes in the Callitrichinae is likely the result of the recent origin of these loci.

Rhesus macaques represent important animal models for biomedical research. The ability to identify macaque major histocompatibility complex (Mhc) alleles is crucial for fully understanding these models of autoimmune and infectious disease. Here we describe a rapid and unambiguous way to distinguish DRB alleles in the rhesus macaque using the polymerase chain reaction, denaturing gradient gel electrophoresis (DGGE), and direct sequencing. The highly variable second exon of Mamu-DRB alleles was amplified using generic DRB primers and alleles were separated by DGGE. DNA was then reamplified from plugs removed from the gel and alleles were determined using fluorescent-based sequencing. Validity of this typing procedure was confirmed by identification of all DRB alleles for three macaques previously characterized by cloning and sequencing techniques. Importantly, our analysis revealed DRB alleles not previously identified in the three reference animals. Using this technique, we identified 40 alleles in fifteen unrelated macaques. On the basis of phylogenetic tree analyses, 14 new DRB alleles were assigned to 10 different Mhc-DRB lineages. Interestingly, two of the new DRB6 lineages had previously been identified in prosimians and pigtailed macaques. Whereas traditional DRB typing methods provide limited information, our new technique provides a simple and relatively rapid way of identifying DRB alleles for tissue typing, determining individual identification and studies of disease association and susceptibility. This new technique should also contribute to ongoing studies of Mhc function and evolution in many different species of nonhuman primates.