Biology subjects

Goss, G. G.

Publications and source records attributed to Goss, G. G..

2 recordsLinked to original sources

bioRxiv2024

Intraspecific differences in alkaline tolerance in brook stickleback (Culaea inconstans) inhabiting neutral and alkaline lakes

Exposure to alkaline water (pH > 9.0) is physiologically challenging for fish, yet our understanding of the physiology of alkaline tolerance in fishes is limited to a small number of ihighly specialized species. This study aimed to characterize mechanisms of alkaline tolerance in brook stickleback (Culaea inconstans), a fish species with a broad pH habitat range, including highly alkaline waters such as Buffalo Lake (pH = 9.2) in Alberta, Canada. Stickleback from Buffalo Lake and a neutral reference lake (Buck Lake; pH = 8.2) were collected from the wild and acclimated to common conditions (pH = 8.0) for at least 2 months. Both populations were then exposed to alkaline conditions (pH = 9.5), resulting in a significant decrease in survival (14% by 7 d of exposure) in Buck Lake fish, but no mortality in Buffalo Lake stickleback. In a 4-d exposure to alkaline water, fish from both populations experienced characteristic inhibitions of ammonia excretion followed by subsequent recovery, in conjunction with an accumulation of ammonia within the body. However, no differences were observed between populations. Analysis of tissue Na+ and Cl- content showed a more pronounced decrease in Cl- in Buck Lake fish, suggesting that tighter regulation of Cl- homeostasis and/or acid-base balance may be an important feature of alkaline tolerance. RNA-sequencing analysis highlighted large differences in gene expression between the alkaline and neutral lake populations, and in response to alkaline exposure. Few of these changes in the expression involved genes known to be associated with nitrogen, ion, or acid-base balance. These data indicate that alkaline tolerance is higher in brook stickleback resident to an alkaline lake than those sourced from a neutral lake, a trait that may be related to differences in physiological and transcriptomic responses to alkaline exposure.

physiology↗

bioRxiv2024

ATP and glutamate coordinate contractions in the freshwater sponge Ephydatia muelleri

Sponges (phylum Porifera) are an early diverging animal lineage that lacks both conventional nervous and muscular systems, and yet they are able to produce coordinated whole-body contractions in response to disturbances. Little is known about the underlying signaling mechanisms in coordinating such responses. Previous studies demonstrated that sponges respond specifically to neuroactive chemicals such as L-glutamate and {gamma}-amino-butyric acid (GABA), which trigger and prevent contractions respectively. Genes for purinergic P2X-like receptors are present in several sponge genomes, leading us to ask whether ATP works with glutamate to coordinate contractions in sponges as it does in other animal nervous systems. Using pharmacological approaches on the freshwater sponge Ephydatia muelleri, we show that ATP is involved in coordinating contractions. Bath applications of ATP cause a rapid, sustained expansion of the excurrent canals in a dose-dependent manner. Complete contractions occur when ATP is added in the presence of apyrase, an enzyme that hydrolyzes ATP. Applying ADP, the first metabolic product of ATP hydrolysis, triggers complete contractions, whereas AMP, the subsequent metabolite, does not trigger a response. Blocking ATP from binding and activating P2X receptors with pyridoxalphosphate-6-azophenyl-2,4-disulfonic acid (PPADS) prevents both glutamate- and ATP-triggered contractions, suggesting that ATP works downstream of glutamate. Bioinformatic analysis revealed two P2X receptor sequences, one which groups with other vertebrate P2X receptors. Altogether, our results confirm that purinergic signaling by ATP is involved in coordinating contractions in the freshwater sponge suggesting a role of ATP-mediated signaling that predates the evolution of the nervous system and multicellularity in animals. Summary statementNerveless sponges coordinate a sneeze-like reflex using glutamate and ATP signaling to expel water from the body.

physiology↗