scholarly journals The coral symbiont Candidatus Aquarickettsia is variably abundant in threatened Caribbean acroporids and transmitted horizontally

2021 ◽  
Author(s):  
Lydia J. Baker ◽  
Hannah G. Reich ◽  
Sheila A. Kitchen ◽  
J. Grace Klinges ◽  
Hanna R. Koch ◽  
...  
Keyword(s):  
Positive Selection ◽  
Coral Disease ◽  
Horizontal Transmission ◽  
Geographic Location ◽  
Geographic Region ◽  
Pcr Analysis ◽  
Coral Host ◽  
Acropora Cervicornis ◽  
Coral Colony ◽  
Algal Symbiont

AbstractThe symbiont “Candidatus Aquarickettsia rohweri” infects a diversity of aquatic hosts. In the threatened Caribbean coral, Acropora cervicornis, Aquarickettsia proliferates in response to increased nutrient exposure, resulting in suppressed growth and increased disease susceptibility and mortality of coral. This study evaluated the extent, as well as the ecology and evolution of Aquarickettsia infecting threatened corals, Ac. cervicornis, and Ac. palmata and their hybrid (“Ac. prolifera”). Aquarickettsia was found in all acroporids, with coral host and geographic location impacting the infection magnitude. Phylogenomic and genome-wide single-nucleotide variant analysis of Aquarickettsia found phylogenetic clustering by geographic region, not by coral taxon. Analysis of Aquarickettsia fixation indices suggests multiple sequential infections of the same coral colony are unlikely. Furthermore, relative to other Rickettsiales species, Aquarickettsia is undergoing positive selection, with Florida populations experiencing greater positive selection relative to other Caribbean locations. This may be due in part to Aquarickettsia proliferating in response to greater nutrient stress in Florida, as indicated by greater in situ replication rates in these corals. Aquarickettsia was not found to significantly codiversify with either the coral animal or the coral’s algal symbiont (Symbiodinium “fitti”). Quantitative PCR analysis showed that gametes, larvae, recruits, and juveniles from susceptible, captive-reared coral genets were not infected with Aquarickettsia. Thus, horizontal transmission of Aquarickettsia via coral mucocytes or an unidentified host is more likely. The prevalence of Aquarickettsia in Ac. cervicornis and its high abundance in the Florida coral population suggests that coral disease mitigation efforts focus on preventing early infection via horizontal transmission.

scholarly journals The coral symbiont Candidatus Aquarickettsia is variably abundant in threatened Caribbean acroporids and transmitted horizontally

2021 ◽  
Author(s):  
Lydia J. Baker ◽  
Hannah G. Reich ◽  
Sheila A. Kitchen ◽  
J. Grace Klinges ◽  
Hanna R. Koch ◽  
...  
Keyword(s):  
Positive Selection ◽  
Horizontal Transmission ◽  
Sampling Location ◽  
Acropora Cervicornis ◽  
Single Nucleotide ◽  
Algal Symbiont ◽  
Genome Wide ◽  
The Us ◽  
Variant Analysis

AbstractThe aquatic symbiont “Candidatus Aquarickettsia rohweri” infects a diversity of non-bilaterian metazoan phyla. In the threatened coral Acropora cervicornis, Aquarickettsia proliferates in response to increased nutrient exposure, resulting in suppressed growth and increased disease susceptibility and mortality. This study evaluated the extent, as well as the ecology and evolution of Aquarickettsia infecting the Caribbean corals: Ac. cervicornis and Ac. palmata and their hybrid (‘Ac. prolifera’). The bacterial parasite Aquarickettsia was found in all acroporids, with host and sampling location impacting infection magnitude. Phylogenomic and genome-wide single nucleotide variant analysis found Aquarickettsia clustering by region, not by coral taxon. Fixation analysis suggested within coral colonies, Aquarickettsia are genetically isolated to the extent that reinfection is unlikely. Relative to other Rickettsiales, Aquarickettsia is undergoing positive selection, with Florida populations experiencing greater positive selection relative to the other Caribbean locations. This may be due to Aquarickettsia response to increased nutrient stress in Florida, as indicated by greater in situ replication rates in these corals. Aquarickettsia did not significantly codiversify with either coral animal nor algal symbiont, and qPCR analysis of gametes and juveniles from susceptible coral genotypes indicated absence in early life stages. Thus, despite being an obligate parasite, Aquarickettsia must be horizontally transmitted via coral mucocytes, an unidentified secondary host, or a yet unexplored environmentally mediated mechanism. Importantly, the prevalence of Aquarickettsia in Ac. cervicornis and high abundance in Florida populations suggests that disease mitigation efforts in the US and Caribbean should focus on preventing early infection via horizontal transmission.

scholarly journals Cladocopium community divergence in two Acropora coral hosts across multiple spatial scales

2019 ◽  
Author(s):  
SW Davies ◽  
K Moreland ◽  
DC Wham ◽  
MR Kanke ◽  
MV Matz
Keyword(s):  
Host Species ◽  
Spatial Scales ◽  
Horizontal Transmission ◽  
Host Specialization ◽  
Coral Host ◽  
Acropora Digitifera ◽  
Algal Symbionts ◽  
Algal Symbiont ◽  
Acropora Hyacinthus ◽  
Significant Genetic Divergence

AbstractMany broadly-dispersing corals acquire their algal symbionts (Symbiodiniaceae) ‘horizontally’ from their environment upon recruitment. Horizontal transmission could promote coral fitness across diverse environments provided that corals can associate with divergent algae across their range and that these symbionts exhibit reduced dispersal potential. Here we quantified community divergence of Cladocopium algal symbionts in two coral host species (Acropora hyacinthus, Acropora digitifera) across two spatial scales (reefs on the same island, and between islands) across the Micronesian archipelago using microsatellites. We find that both hosts associated with two genetically distinct Cladocopium lineages (C40, C21), confirming that Acropora coral hosts associate with a range of Cladocopium symbionts across this region. Both C40 and C21 exhibited extensive clonality. Clones not only existed across host conspecifics living on the same reef, but also spanned host species, reef sites within islands, and even different islands. Both Cladocopium lineages exhibited moderate host specialization and divergence across islands. In addition, within every island, algal symbiont communities were significantly clustered by both host species and reef site, highlighting that coral-associated Cladocopium communities are structured across small spatial scales and within hosts on the same reef. This is in stark contrast to their coral hosts, which never exhibited significant genetic divergence between reefs on the same island. These results support the view that horizontal transmission could improve local fitness for broadly dispersing Acropora coral species.

scholarly journals Coral mucus rapidly induces chemokinesis and genome-wide transcriptional shifts toward early pathogenesis in a bacterial coral pathogen

2021 ◽  
Author(s):  
Cherry Gao ◽  
Melissa Garren ◽  
Kevin Penn ◽  
Vicente I. Fernandez ◽  
Justin R. Seymour ◽  
...  
Keyword(s):  
Coral Disease ◽  
Fold Increase ◽  
Transcript Abundance ◽  
Coral Tissue ◽  
Coral Host ◽  
Secretion Systems ◽  
Nutrient Metabolism ◽  
Transcriptional Responses ◽  
Coral Mucus ◽  
Algal Symbiont

AbstractElevated seawater temperatures have contributed to the rise of coral disease mediated by bacterial pathogens, such as the globally distributed Vibrio coralliilyticus, which utilizes coral mucus as a chemical cue to locate stressed corals. However, the physiological events in the pathogens that follow their entry into the coral host environment remain unknown. Here, we present simultaneous measurements of the behavioral and transcriptional responses of V. coralliilyticus BAA-450 incubated in coral mucus. Video microscopy revealed a strong and rapid chemokinetic behavioral response by the pathogen, characterized by a two-fold increase in average swimming speed within 6 min of coral mucus exposure. RNA sequencing showed that this bacterial behavior was accompanied by an equally rapid differential expression of 53% of the genes in the V. coralliilyticus genome. Specifically, transcript abundance 10 min after mucus exposure showed upregulation of genes involved in quorum sensing, biofilm formation, and nutrient metabolism, and downregulation of flagella synthesis and chemotaxis genes. After 60 min, we observed upregulation of genes associated with virulence, including zinc metalloproteases responsible for causing coral tissue damage and algal symbiont photoinactivation, and secretion systems that may export toxins. Together, our results suggest that V. coralliilyticus employs a suite of behavioral and transcriptional responses to rapidly shift into a distinct infection mode within minutes of exposure to the coral microenvironment.

scholarly journals Gendered Experiences of Living with HIV in Australia

Sexes ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 244-255
Author(s):  
Vicki Hutton
Keyword(s):  
Mental Health ◽  
Lived Experience ◽  
Case Reports ◽  
Economic Status ◽  
Geographic Location ◽  
Geographic Region ◽  
Gender And Sexuality ◽  
Economic Consequences ◽  
People Living With Hiv ◽  
Living With Hiv

Globally, women represent more than half the people living with HIV. This proportion varies by country, with an over-representation of HIV among men who have sex with men (MSM) in some regions. For example, in Australia, MSM account for over 60% of transmissions, with heterosexual sex accounting for almost a quarter of transmissions. Irrespective of geographic region, there is evidence that women can have a different lived experience of HIV due to their unequal social and economic status in society, while MSM can have a different lived experience depending on the laws and customs of their geographic location. Gender differences related to risk factors, stigma, access to services, mental health, health-related quality of life and economic consequences have been consistently reported globally. This paper explores the subjective lived experience of gender and sexuality disparities among three individuals living with HIV in Australia: a male who identified as gay, and a male and female who each identified as heterosexual. Analysis of themes from these three case reports indicated discernible differences by gender and sexuality in four areas: access to medical services, social support, stigma and mental health. It is argued that knowledge and understanding of potential gender and sexuality disparities must be factored into supportive interventions for people living with HIV in Australia.

scholarly journals Microscale tracking of coral disease reveals timeline of infection and heterogeneity of polyp fate

2018 ◽  
Author(s):  
Assaf R. Gavish ◽  
Orr H. Shapiro ◽  
Esti Kramarsky-Winter ◽  
Assaf Vardi
Keyword(s):  
Disease Progression ◽  
Defense Mechanism ◽  
Coral Disease ◽  
Coral Host ◽  
Pocillopora Damicornis ◽  
Spatial And Temporal Scales ◽  
Infection Dynamics ◽  
Key Steps ◽  
Coral Pathogen ◽  
Gastrovascular System

AbstractCoral disease is often studied at scales ranging from single colonies to the entire reef. This is particularly true for studies following disease progression through time. To gain a mechanistic understanding of key steps underlying infection dynamics, it is necessary to study disease progression, and host-pathogen interactions, at relevant microbial scales. Here we provide a dynamic view of the interaction between the model coral pathogen Vibrio coralliilyticus and its coral host Pocillopora damicornis at unprecedented spatial and temporal scales. This view is achieved using a novel microfluidics-based system specifically designed to allow microscopic study of coral infection in-vivo under controlled environmental conditions. Analysis of exudates continuously collected at the system’s outflow, allows a detailed biochemical and microbial analyses coupled to the microscopic observations of the disease progression. The resulting multilayered dataset provides the most detailed description of a coral infection to-date, revealing distinct pathogenic processes as well as the defensive behavior of the coral host. We provide evidence that infection in this system occurs following ingestion of the pathogen, and may then progress through the gastrovascular system. We further show infection may spread when pathogens colonize lesions in the host tissue. Copious spewing of pathogen-laden mucus from the polyp mouths results in effective expulsion of the pathogen from the gastrovascular system, possibly serving as a first line of defense. A secondary defense mechanism entails the severing of calicoblastic connective tissues resulting in the controlled isolation of diseased polyps, or the survival of individual polyps within infected colonies. Further investigations of coral-pathogen interactions at these scales will help to elucidate the complex interactions underlying coral disease, as we as the versatile adaptive response of the coral ecosystems to fluctuating environments.

scholarly journals Experimental antibiotic treatment identifies potential pathogens of white band disease in the endangered Caribbean coral Acropora cervicornis

2014 ◽  
Vol 281 (1788) ◽  
pp. 20140094 ◽  
Author(s):  
M. J. Sweet ◽  
A. Croquer ◽  
J. C. Bythell
Keyword(s):  
Coral Disease ◽  
Causal Agent ◽  
Acropora Palmata ◽  
Acropora Cervicornis ◽  
Coral Diseases ◽  
White Band ◽  
Disease Causation ◽  
Community Shifts ◽  
White Band Disease ◽  
Experimental Treatments

Coral diseases have been increasingly reported over the past few decades and are a major contributor to coral decline worldwide. The Caribbean, in particular, has been noted as a hotspot for coral disease, and the aptly named white syndromes have caused the decline of the dominant reef building corals throughout their range. White band disease (WBD) has been implicated in the dramatic loss of Acropora cervicornis and Acropora palmata since the 1970s, resulting in both species being listed as critically endangered on the International Union for Conservation of Nature Red list. The causal agent of WBD remains unknown, although recent studies based on challenge experiments with filtrate from infected hosts concluded that the disease is probably caused by bacteria. Here, we report an experiment using four different antibiotic treatments, targeting different members of the disease-associated microbial community. Two antibiotics, ampicillin and paromomycin, arrested the disease completely, and by comparing with community shifts brought about by treatments that did not arrest the disease, we have identified the likely candidate causal agent or agents of WBD. Our interpretation of the experimental treatments is that one or a combination of up to three specific bacterial types, detected consistently in diseased corals but not detectable in healthy corals, are likely causal agents of WBD. In addition, a histophagous ciliate ( Philaster lucinda ) identical to that found consistently in association with white syndrome in Indo-Pacific acroporas was also consistently detected in all WBD samples and absent in healthy coral. Treatment with metronidazole reduced it to below detection limits, but did not arrest the disease. However, the microscopic disease signs changed, suggesting a secondary role in disease causation for this ciliate. In future studies to identify a causal agent of WBD via tests of Henle–Koch's postulates, it will be vital to experimentally control for populations of the other potential pathogens identified in this study.

Genome-wide identification, phylogenetic and expressional analysis of the UXS gene family in cotton

2020 ◽  
Author(s):  
Yuxin Pan ◽  
Jinpeng Wang ◽  
Zhenyi Wang ◽  
Hengwei Liu ◽  
Lan Zhang ◽  
...  
Keyword(s):  
Positive Selection ◽  
Gene Family ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Subcellular Location ◽  
Pcr Analysis ◽  
Genome Wide ◽  
Cotton Species ◽  
Expressional Analysis ◽  
Significant Positive Selection

Abstract Background: UDP-glucuronate decarboxylase (UXS) is an enzyme in plants and participates in cell wall noncellulose. Previous research suggested that cotton GhUXS gene regulated the conversion of non-cellulosic polysaccharides and modulates their composition in plant cell walls, showing its possible cellular function determining the quality of cotton fibers. Here, we performed evolutionary, phylogenetic, and expressional analysis of UXS genes from cottons and other selected plants. Results: By exploring the sequenced cotton genomes, we identified 10, 10, 18, and 20 UXSs genes in Gossypium raimondii , Gossypium arboretum , Gossypium hirsutum and Gossypium barbadense , and retrieved their homologs from other representative plants, including 5 dicots, 1 monocot, 5 green alga, 1 moss, and 1 lycophyte. Phylogenetic analysis suggested that UXS genes could be divided into four subgroups and members within each subgroup shared similar exon-intron structures, motif and subcellular location. Notably, gene colinearity information indicates 100% constructed trees to have aberrant topology, and helps determine and use corrected phylogeny. In spite of conservative nature of UXS, during the evolution of Gossypium , UXS genes were subjected to significant positive selection on key evolutionary nodes. Expression profiles derived from RNA-seq data showed distinct expression patterns of GhUXS genes in various tissues and different development. Most of GhUXS gene expressed highly at 10, 20 and 25 DPA (day post anthesis) of fibers. Real-time quantitative PCR analysis GhUXS genes expressed highly at 20 DPA or 25 DPA. Conclusions: UXS is relatively conserved in plants and significant positive selection affects cotton UXS evolution. The comparative genome-wide identification and expression profiling would lay an important foundation to understanding the biological functions of UXS gene family in cotton species and other plants.

scholarly journals Differential Responses of the Coral Host and Their Algal Symbiont to Thermal Stress

PLoS ONE ◽  
2011 ◽  
Vol 6 (10) ◽  
pp. e26687 ◽  
Author(s):  
William Leggat ◽  
Francois Seneca ◽  
Kenneth Wasmund ◽  
Lubna Ukani ◽  
David Yellowlees ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Coral Host ◽  
Algal Symbiont ◽  
Differential Responses

scholarly journals Variation in susceptibility among three Caribbean coral species and their algal symbionts indicates the threatened staghorn coral, Acropora cervicornis, is particularly susceptible to elevated nutrients and heat stress

2021 ◽  
Author(s):  
Ana M. Palacio-Castro ◽  
Caroline E. Dennison ◽  
Stephanie M. Rosales ◽  
Andrew C. Baker
Keyword(s):  
Heat Stress ◽  
Coral Species ◽  
Coral Cover ◽  
Photochemical Efficiency ◽  
Acropora Cervicornis ◽  
Nutrient Inputs ◽  
Algal Symbionts ◽  
Algal Symbiont ◽  
Orbicella Faveolata ◽  
Significant Mortality

Coral cover is declining worldwide due to multiple interacting threats. We compared the effects of elevated nutrients and temperature on three Caribbean corals: Acropora cervicornis, Orbicella faveolata, and Siderastrea siderea. Colonies hosting different algal types were exposed to either ambient nutrients (A), elevated NH4 (N), or elevated NH4 + PO4 (N+P) at control temperatures (26 °C) for > 2 months, followed by a 3-week thermal challenge (31.5 °C). A. cervicornis hosted Symbiodinium (S. fitti) and was highly susceptible to the combination of elevated nutrients and temperature. During heat stress, A. cervicornis pre-exposed to elevated nutrients experienced 84%-100% mortality and photochemical efficiency (Fv/Fm) declines of 41-50%. In comparison, no mortality and lower Fv/Fm declines (11-20%) occurred in A. cervicornis that were heat-stressed but not pre-exposed to nutrients. O. faveolata and S. siderea response to heat stress was determined by their algal symbiont community and was not affected by nutrients. O. faveolata predominantly hosted Durusdinium trenchii or Breviolum, but only corals hosting Breviolum were susceptible to heat, experiencing 100% mortality, regardless of nutrient treatment. S. siderea colonies predominantly hosted Cladocopium C1 (C. goreaui), Cladocopium C3, D. trenchii, or variable proportions of Cladocopium C1 and D. trenchii. This species was resilient to elevated nutrients and temperature, with no significant mortality in any of the treatments. However, during heat stress, S. siderea hosting Cladocopium C3 suffered higher reductions in Fv/Fm (41-56%) compared to S. siderea hosting Cladocopium C1 and D. trenchii (17-26% and 10-16%, respectively). These differences in holobiont susceptibility to elevated nutrients and heat may help explain historical declines in A. cervicornis starting decades earlier than other Caribbean corals. Our results suggest that tackling only warming temperatures may be insufficient to ensure the continued persistence of Caribbean corals, especially A. cervicornis. Reducing nutrient inputs to reefs may also be necessary for these iconic coral species to survive.

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