The redundancy and diversity between two novel PKC isotypes that regulate learning in Caenorhabditis elegans

The nematode Caenorhabditis elegans learns the concentration of NaCl and moves toward the previously experienced concentration. In this behavior, the history of NaCl concentration change is reflected in the level of diacylglycerol and the activity of protein kinase C, PKC-1, in the gustatory sensory neuron ASER and determines the direction of migration. Here, through a genetic screen, we found that the activation of Gq protein compensates for the behavioral defect of the loss-of-function mutant of pkc-1. We found that Gq activation results in hyperproduction of diacylglycerol in ASER sensory neuron, which leads to recruitment of TPA-1, an nPKC isotype closely related to PKC-1. Unlike the pkc-1 mutants, loss of tpa-1 did not obviously affect migration directions in the conventional learning assay. This difference was suggested to be due to cooperative functions of the C1 and C2-like domains of the nPKC isotypes. Furthermore, we investigated how the compensatory capability of tpa-1 contributes to learning and found that learning was less robust in the context of cognitive decline or environmental perturbation in tpa-1 mutants. These results highlight how two nPKC isotypes contribute to the learning system.

Miniaturization during a Silurian environmental crisis generated the modern brittle star body plan

Pivotal anatomical innovations often seem to appear by chance when viewed through the lens of the fossil record. As a consequence, specific driving forces behind the origination of major organismal clades generally remain speculative. Here, we present a rare exception to this axiom by constraining the appearance of a diverse animal group (the living Ophiuroidea) to a single speciation event rather than hypothetical ancestors. Fossils belonging to a new pair of temporally consecutive species of brittle stars (Ophiopetagno paicei gen. et sp. nov. and Muldaster haakei gen. et sp. nov.) from the Silurian (444–419 Mya) of Sweden reveal a process of miniaturization that temporally coincides with a global extinction and environmental perturbation known as the Mulde Event. The reduction in size from O. paicei to M. haakei forced a structural simplification of the ophiuroid skeleton through ontogenetic retention of juvenile traits, thereby generating the modern brittle star bauplan.

Gorgonian Responses to Environmental Change on Coral Reefs in SE Sulawesi, Indonesia

<p>Gorgonian corals (Cnidaria: Anthozoa: Octocorallia) are conspicuous, diverse and often dominant components of benthic marine environments. Intra- & interspecific morphological variability in gorgonians are influenced by environmental factors such as light, sedimentation and flow rates. Yet, little is known about the responses of gorgonian taxa to environmental parameters particularly in Indonesia, despite their high regional abundance and diversity. With a burgeoning human population and subsequent marine resource exploitation, reefs throughout the Indonesian archipelago are under rapid decline and often destroyed. Conservation surveys are however, underway with a tendency to overlook gorgonian taxa primarily due to unresolved taxonomic assignment leading to difficulties in field identification. The aims of this study were to: 1) characterise gorgonian diversity and ecology across a gradient of habitat quality within the Wakatobi Marine National Park (WMNP), SE Sulawesi, Indonesia, 2) assess morphological and genetic variability between morphotypes of the ubiquitous zooxanthellate isidid Isis hippuris Linnaeus 1758 from healthy and degraded reefs, 3) determine if I. hippuris morphotypes are environmentally induced (plastic) or genetically derived through reciprocal transplant experiments (RTEs) between contrasting reefs and thus, 4) identify mechanisms of plasticity capacity or divergence through phenotypic trait integration in response to environmental change. Ecological surveys revealed considerable gorgonian diversity with a total of 197 species and morphotypes from 42 genera, and 12 families within the suborders Calcaxonia and Holaxonia and the group Scleraxonia, with current estimates of over 21 new species and 28 new species records for the region. Gorgonian abundance and diversity increased with reef health and bathymetry. However, a clear loss of gorgonian diversity existed with increased sedimentation and reduced light due to anthropogenic disturbance. In particular, two distinct I. hippuris morphotypes were highly abundant between environmental clines: short-branched multi/planar colonies on healthy reefs, and long-branched bushy colonies on degraded reefs. Comparative morphological and molecular analyses using ITS2 sequence and predicted secondary structure, further corroborated haplotype differences relative to morphotypes between environments. However, unsatisfactory assignment of I. hippuris morphotypes to previously described alternatives (Isis reticulata Nutting 1910, Isis minorbrachyblasta Zou, Huang & Wang 1991) questions the validity to such taxonomic assignments. Phylogenetic analyses also confirm that the polyphyletic nature of the Isididae lies in its type species I. hippuris, being unrelated to the rest of its family members. A one-year RTE revealed three key results, that: 1) reduced survivorship of healthy reef morphotypes on degraded reefs implied the onset of lineage segregation through immigrant inviability, 2) prominent phenotypic traits were at the morphological and bio-optical levels revealing high phenotypic plasticity in healthy clones, and relative insensitivity to environmental change in degraded reef morphotypes, indicative of local adaptation leading to incipient ecological divergence, and 3) photoacclimation at the bio-optical level was not attributed to endosymbiont diversity or shuffling, with all test colonies possessing a novel clade D1a Symbiodinium. While it is clear that gorgonian taxa within the WMNP are of exceptional diversity and abundance, responses to environmental perturbation highlight three pertinent, testable ideas. Firstly, increased species richness specifically with depth in azooxanthellate taxa, invite tests of deep-reef refugia previously established through geological change. Secondly, ecological assessment targets research on informative taxa for focused systematics and mechanisms of phenotypic divergence. Thirdly, exploring intrinsic and extrinsic interactions that define the host-symbiont relationship and differential biological success using physiological and next generation sequencing approaches. These objectives would provide considerable insight into the evolutionary processes to environmental change, accelerated by anthropogenic encroachment. Taken together, this work signifies that gorgonian corals within the WMNP are of foremost diversity and concern, exhibiting informative ecological and mechanistic responses to environmental perturbation. This evidence elicits tests of deep-reef refugia, priority systematics, mechanisms of ecological divergence and physiological assessment. Such tests inevitably expand our understanding of the intrinsic and extrinsic associations of gorgonian taxa to environmental change from an historical and predictive perspective yielding benefits to conservation assessment and management.</p>

Gorgonian Responses to Environmental Change on Coral Reefs in SE Sulawesi, Indonesia

<p>Gorgonian corals (Cnidaria: Anthozoa: Octocorallia) are conspicuous, diverse and often dominant components of benthic marine environments. Intra- & interspecific morphological variability in gorgonians are influenced by environmental factors such as light, sedimentation and flow rates. Yet, little is known about the responses of gorgonian taxa to environmental parameters particularly in Indonesia, despite their high regional abundance and diversity. With a burgeoning human population and subsequent marine resource exploitation, reefs throughout the Indonesian archipelago are under rapid decline and often destroyed. Conservation surveys are however, underway with a tendency to overlook gorgonian taxa primarily due to unresolved taxonomic assignment leading to difficulties in field identification. The aims of this study were to: 1) characterise gorgonian diversity and ecology across a gradient of habitat quality within the Wakatobi Marine National Park (WMNP), SE Sulawesi, Indonesia, 2) assess morphological and genetic variability between morphotypes of the ubiquitous zooxanthellate isidid Isis hippuris Linnaeus 1758 from healthy and degraded reefs, 3) determine if I. hippuris morphotypes are environmentally induced (plastic) or genetically derived through reciprocal transplant experiments (RTEs) between contrasting reefs and thus, 4) identify mechanisms of plasticity capacity or divergence through phenotypic trait integration in response to environmental change. Ecological surveys revealed considerable gorgonian diversity with a total of 197 species and morphotypes from 42 genera, and 12 families within the suborders Calcaxonia and Holaxonia and the group Scleraxonia, with current estimates of over 21 new species and 28 new species records for the region. Gorgonian abundance and diversity increased with reef health and bathymetry. However, a clear loss of gorgonian diversity existed with increased sedimentation and reduced light due to anthropogenic disturbance. In particular, two distinct I. hippuris morphotypes were highly abundant between environmental clines: short-branched multi/planar colonies on healthy reefs, and long-branched bushy colonies on degraded reefs. Comparative morphological and molecular analyses using ITS2 sequence and predicted secondary structure, further corroborated haplotype differences relative to morphotypes between environments. However, unsatisfactory assignment of I. hippuris morphotypes to previously described alternatives (Isis reticulata Nutting 1910, Isis minorbrachyblasta Zou, Huang & Wang 1991) questions the validity to such taxonomic assignments. Phylogenetic analyses also confirm that the polyphyletic nature of the Isididae lies in its type species I. hippuris, being unrelated to the rest of its family members. A one-year RTE revealed three key results, that: 1) reduced survivorship of healthy reef morphotypes on degraded reefs implied the onset of lineage segregation through immigrant inviability, 2) prominent phenotypic traits were at the morphological and bio-optical levels revealing high phenotypic plasticity in healthy clones, and relative insensitivity to environmental change in degraded reef morphotypes, indicative of local adaptation leading to incipient ecological divergence, and 3) photoacclimation at the bio-optical level was not attributed to endosymbiont diversity or shuffling, with all test colonies possessing a novel clade D1a Symbiodinium. While it is clear that gorgonian taxa within the WMNP are of exceptional diversity and abundance, responses to environmental perturbation highlight three pertinent, testable ideas. Firstly, increased species richness specifically with depth in azooxanthellate taxa, invite tests of deep-reef refugia previously established through geological change. Secondly, ecological assessment targets research on informative taxa for focused systematics and mechanisms of phenotypic divergence. Thirdly, exploring intrinsic and extrinsic interactions that define the host-symbiont relationship and differential biological success using physiological and next generation sequencing approaches. These objectives would provide considerable insight into the evolutionary processes to environmental change, accelerated by anthropogenic encroachment. Taken together, this work signifies that gorgonian corals within the WMNP are of foremost diversity and concern, exhibiting informative ecological and mechanistic responses to environmental perturbation. This evidence elicits tests of deep-reef refugia, priority systematics, mechanisms of ecological divergence and physiological assessment. Such tests inevitably expand our understanding of the intrinsic and extrinsic associations of gorgonian taxa to environmental change from an historical and predictive perspective yielding benefits to conservation assessment and management.</p>

Blind cavefish retain functional connectivity in the tectum despite loss of retinal input

Sensory systems display remarkable plasticity and are under strong evolutionary selection. The Mexican cavefish, Astyanax mexicanus, consists of eyed river-dwelling surface populations, and multiple independent cave populations which have converged on eye loss, providing the opportunity to examine the evolution of sensory circuits in response to environmental perturbation. Functional analysis across multiple transgenic populations expressing GCaMP6s showed that functional connectivity of the optic tectum largely did not differ between populations, except for the selective loss of negatively correlated activity within the cavefish tectum, suggesting positively correlated neural activity is resistant to an evolved loss of input from the retina. Further, analysis of surface-cave hybrid fish reveals that changes in the tectum are genetically distinct from those encoding eye-loss. Together, these findings uncover the independent evolution of multiple components of the visual system and establish the use of functional imaging in A. mexicanus to study neural circuit evolution.

Optimizing Protocols for High-Quality RNA Extraction from Blood and Liver Tissues of the Broad-Snouted Caiman

Transcriptomic information provides fundamental insights into biological processes and can be used to determine gene expression in cell, tissue, or organism under specific physiological conditions, or in response to any environmental perturbation. Extraction of high quality RNA is a challenging step mainly in non-traditional organisms, and protocols for preservation and isolation need to be adjusted in many cases. In the present work, we aimed to develop a protocol for preservation and isolation of high-quality and quantity of RNA from blood and liver tissues of Caiman latirostris. Three preservation methods were tested: 1) flash freezing (LN2) and storage at –80°C; 2) RNAlater® conservation with progressive cooling up to –80°C); 3) preservation in TRIzol® reagent, flash freezing in LN2 and storage at –80°C. Methods 1 and 2 were tested for liver, while 2 and 3 for blood. Our results showed that both preservation methods resulted in excellent outcomes for liver samples. For blood samples however, TRIzol® preservation was an efficient procedure for adequate RNA quality, quantity, and integrity, while conservation in RNAlater® solution was inadequate in both quality and quantity for an optimal RNA extraction. Appropriate protocols were established for each tissue and are being used now for transcriptomic studies in this sentinel organism.

The Diguanylate Cyclase YfiN of Pseudomonas aeruginosa Regulates Biofilm Maintenance in Response to Peroxide

Pseudomonas aeruginosa forms surface-attached communities that persist in the face of antimicrobial agents and environmental perturbation. Published work has found extracellular polysaccharide (EPS) production, regulation of motility and induction of stress response pathways as contributing to biofilm tolerance during such insults. However, little is known regarding the mechanism(s) whereby biofilm maintenance is regulated when exposed to such environmental challenges. Here, we provide evidence that the diguanylate cyclase YfiN is important for the regulation of biofilm maintenance when exposed to peroxide. We find that, compared to the wild type (WT), static biofilms of the ΔyfiN mutant exhibit a maintenance defect, which can be further exacerbated by exposure to peroxide (H2O2); this defect can be rescued through genetic complementation. Additionally, we found that the ΔyfiN mutant biofilms produce less c-di-GMP than WT, and that H2O2 treatment enhanced motility of surface-associated bacteria and increased cell death for the ΔyfiN mutant grown as a biofilm compared to WT biofilms. These data provide evidence that YfiN is required for biofilm maintenance by P. aeruginosa, via c-di-GMP signaling, to limit motility and protect viability in response to peroxide stress. These findings add to the growing recognition that biofilm maintenance by P. aeruginosa is an actively regulated process that is controlled, at least in part, by the wide array of c-di-GMP metabolizing enzymes found in this microbe.