surface dwelling
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2022 ◽  
Author(s):  
Jaya Krishnan ◽  
Yan Wang ◽  
Olga Kenzior ◽  
Huzaifa Hassan ◽  
Luke Olsen ◽  
...  

Cell lines have become an integral resource and tool for conducting biological experiments ever since the Hela cell line was first developed (1). They not only allow detailed investigation of molecular pathways but are faster and more cost-effective than most in vivo approaches. The last decade saw many emerging model systems strengthening basic science research. However, lack of genetic and molecular tools in these newer systems pose many obstacles. Astyanax mexicanus is proving to be an interesting new model system for understanding metabolic adaptation. To further enhance the utility of this system, we developed liver-derived cell lines from both surface-dwelling and cave-dwelling morphotypes. In this study, we provide detailed methodology of the derivation process along with a comprehensive biochemical and molecular characterization of the cell lines, which reflects key metabolic traits of cavefish adaptation. We anticipate these cell lines to become a useful resource for the Astyanax community as well as researchers investigating fish biology, comparative physiology, and metabolism.


eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Corine M van der Weele ◽  
William R Jeffery

Dark caves lacking primary productivity can expose subterranean animals to hypoxia. We used the surface-dwelling (surface fish) and cave-dwelling (cavefish) morphs of Astyanax mexicanus as a model for understanding the mechanisms of hypoxia tolerance in the cave environment. Primitive hematopoiesis, which is restricted to the posterior lateral mesoderm in other teleosts, also occurs in the anterior lateral mesoderm in Astyanax, potentially pre-adapting surface fish for hypoxic cave colonization. Cavefish have enlarged both hematopoietic domains and develop more erythrocytes than surface fish, which are required for normal development in both morphs. Laboratory induced hypoxia suppresses growth in surface fish but not in cavefish. Both morphs respond to hypoxia by overexpressing hypoxia-inducible factor 1 (hif1) pathway genes, and some hif1 genes are constitutively upregulated in normoxic cavefish to similar levels as in hypoxic surface fish. We conclude that cavefish cope with hypoxia by increasing erythrocyte development and constitutive hif1 gene overexpression.


2021 ◽  
Vol 76 (1) ◽  
Author(s):  
Gábor Herczeg ◽  
Viktória Nyitrai ◽  
Gergely Balázs ◽  
Gergely Horváth

Abstract Behavioural innovativeness is important for colonising new habitats; however, it is also costly. Along the colonisation event of a simple, stable and isolated habitat offering only new food sources, one could hypothesize that the colonising individuals are more innovative than the average in their source population, showing preference to the new resource, while after colonisation, the adapted population will lose its innovativeness and become specialised to the new resource. To test this hypothesis, we compared food preference and food type innovation of a cave-dwelling waterlouse (Asellus aquaticus) population (genetically isolated for at least 60 000 years) to three surface-dwelling populations, also sampling individuals that have recently entered the cave (‘colonists’). In the cave, the only food sources are endogenous bacterial mats, while surface populations feed on various living and dead plant material together with their fungal and bacterial overgrow. We assayed all populations with the familiar and unfamiliar food types from the natural habitats and two novel food types not occurring in the natural habitats of the species. We found that all populations preferred surface to cave food and consumed the unnatural novel food types. Surface populations avoided cave food and colonists spent the most time with feeding on surface food. We conclude that the cave population maintained its preference for surface food and did not lose its food type innovativeness. We suggest that adapting to the special cave food was a major challenge in colonising the cave. Significance statement Behavioural innovativeness is a key trait for adapting to environmental changes or to colonise new habitats. However, it has developmental and maintenance costs due to the high energy need of the necessary sensory and neural organs. Therefore, we asked whether behavioural innovativeness decreases after colonising an isolated, stable and highly specialised habitat. By comparing food type innovativeness of surface-dwelling populations of waterlouse (Asellus aquaticus) to a population that has colonised a cave at least 60 000 years ago, we found that the high innovativeness towards unnatural food was retained in the cave population. Further, all populations preferred surface food (decaying leaves), with surface populations almost completely avoiding cave food (endogenous bacteria mats). We suggest that (i) food type innovativeness is evolutionary rigid in our system and (ii) the cave food was rather an obstacle against than a trigger of cave colonisation.


2021 ◽  
Author(s):  
Perry G Beasley-Hall ◽  
Terry Bertozzi ◽  
Tessa M Bradford ◽  
Charles S P Foster ◽  
Karl Jones ◽  
...  

Subterranean habitats are environmentally stable with respect to temperature, humidity, and the absence of light. The transition to a subterranean lifestyle might therefore be expected to cause considerable shifts in an organism's physiology; here, we investigate how subterranean colonisation affects thermal tolerance. Subterranean organisms might be at an increased risk of decline in the face of global temperature rises, but robust data on the fauna is lacking, particularly at the molecular level. In this study we compare the heat shock response of two species of diving beetle in the genus Paroster: one surface-dwelling (P. nigroadumbratus), the other restricted to a single aquifer (P. macrosturtensis). P. macrosturtensis has been previously established as having a lower thermal tolerance compared to surface-dwelling relatives, but the genomic basis of this difference is unknown. By sequencing transcriptomes of experimentally heat-shocked individuals and performing differential expression analysis, we demonstrate both species can mount a heat shock response at high temperatures (35C), in agreement with past survival experiments. However, the genes involved in these responses differ between species, and far greater genes are differentially expressed in the surface species, which may explain its more robust response to heat stress. In contrast, the subterranean species significantly upregulated the heat shock protein gene Hsp68 in the experimental setup under conditions it would likely encounter in nature (25C), suggesting it may be more sensitive to ambient stressors, e.g. handling. The results presented here contribute to an emerging narrative concerning weakened thermal tolerances in obligate subterranean organisms at the molecular level.


2021 ◽  
Author(s):  
Zhi-Jin Liu ◽  
Xiong-Fei Zhang ◽  
Hua-Mei Wen ◽  
Ling Han ◽  
Jiang Zhou

Abstract BackgroundLoaches from the superfamily Cobitoidea (Cypriniformes, Nemacheilidae) are small elongated bottom-dwelling freshwater fishes with several barbels near the mouth, and some species of loach inhabit the underground drainage. The genus Oreonectes with 18 currently recognized loach species represent the three key stages of the evolutionary process (a surface-dwelling lifestyle, facultative cave persistence, and permanent cave dwelling). Some Oreonectes species show typical cave dwelling-related traits, such as partial or complete leucism and regression of the eyes, rendering them as suitable study objects of micro-evolution. Genome information of Oreonectes species is therefore an indispensable research resource of the evolution of cavefishes.ResultWe assembled the genome sequence of O. shuilongensis, a surface-dwelling species, using an integrated approach that combined PacBio single-molecule real-time sequencing and Illumina X-ten paired-end sequencing. The genome assembly contains 803 contigs with N50 values of 5.58 Mb. 25,247 protein-coding genes were predicted, of which 95.65% have been functionally annotated. Meanwhile,we found that dozens of genes related to eye development and melanogenesis were pseudogenised during the evolutionary process in cave environment, providing novel insights into complex phenotypic adaptations of animals in specific environment. ConclusionHere we report the first draft genome assembly of Oreonectes fishes, which is also the first genome reference for Cobitidea fishes. This genome assembly will contribute to the study of the evolution and adaptation of cavefishes within Oreonectes and beyond (Cobitidea) and provid valuable genomic resources for studies on the evolutionary history of the rapid speciation processes of family Nemacheilidae.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paul E. Marek ◽  
Bruno A. Buzatto ◽  
William A. Shear ◽  
Jackson C. Means ◽  
Dennis G. Black ◽  
...  

AbstractThe name “millipede” translates to a thousand feet (from mille “thousand” and pes “foot”). However, no millipede has ever been described with more than 750 legs. We discovered a new record-setting species of millipede with 1,306 legs, Eumillipes persephone, from Western Australia. This diminutive animal (0.95 mm wide, 95.7 mm long) has 330 segments, a cone-shaped head with enormous antennae, and a beak for feeding. A distant relative of the previous record holder, Illacme plenipes from California, it belongs to a different order, the Polyzoniida. Discovered 60 m below ground in a drill hole created for mineral exploration, E. persephone possesses troglomorphic features; it lacks eyes and pigmentation, and it has a greatly elongated body—features that stand in stark contrast to its closest surface-dwelling relatives in Australia and all other members of its order. Using phylogenomics, we found that super-elongation (> 180 segments) evolved repeatedly in the millipede class Diplopoda. The striking morphological similarity between E. persephone and I. plenipes is a result of convergent evolution, probably for locomotion in similar soil habitats. Discovered in the resource-rich Goldfields-Esperance region and threatened by encroaching surface mining, documentation of this species and conservation of its habitat are of critical importance.


2021 ◽  
Vol 22 (23) ◽  
pp. 12851
Author(s):  
Valentina S. Evsiukova ◽  
Daria Bazovkina ◽  
Ekaterina Bazhenova ◽  
Elizabeth A. Kulikova ◽  
Alexander V. Kulikov

The mechanisms of resistance to antidepressant drugs is a key and still unresolved problem of psychopharmacology. Serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) play a key role in the therapeutic effect of many antidepressants. Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in 5-HT synthesis in the brain. We used zebrafish (Danio rerio) as a promising model organism in order to elucidate the effect of TPH2 deficiency caused by p-chlorophenylalanine (pCPA) on the alterations in behavior and expression of 5-HT-related (Tph2, Slc6a4b, Mao, Htr1aa, Htr2aa) and BDNF-related (Creb, Bdnf, Ntrk2a, Ngfra) genes in the brain after prolonged treatment with two antidepressants, inhibitors of 5-HT reuptake (fluoxetine) and oxidation (pargyline). In one experiment, zebrafish were treated for 72 h with 0.2 mg/L fluoxetine, 2 mg/L pCPA, or the drugs combination. In another experiment, zebrafish were treated for 72 h with 0.5 mg/L pargyline, 2 mg/L pCPA, or the drugs combination. Behavior was studied in the novel tank diving test, mRNA levels were assayed by qPCR, 5-HT and its metabolite concentrations were measured by HPLC. The effects of interaction between pCPA and the drugs on zebrafish behavior were observed: pCPA attenuated “surface dwelling” induced by the drugs. Fluoxetine decreased mRNA levels of Tph2 and Htr2aa genes, while pargyline decreased mRNA levels of Slc6a4b and Htr1aa genes. Pargyline reduced Creb, Bdnf and Ntrk2a genes mRNA concentration only in the zebrafish treated with pCPA. The results show that the disruption of the TPH2 function can cause a refractory to antidepressant treatment.


Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1002
Author(s):  
Mengzhen Chen ◽  
Wanru Guo ◽  
Sunbin Huang ◽  
Xiaozhu Luo ◽  
Mingyi Tian ◽  
...  

Cave-dwelling ground beetles in China represent the most impressive specific diversity and morphological adaptations of the cavernicolous ground beetles in the world, but they have not been systematically examined in quantitative terms. The present study focuses on the application of geometric morphological methods to address the morphological adaptations of the tribe Trechini, the most representative group in China. We have employed a geometric morphometry analysis of the head, pronotum, and elytra of 53 genera of Trechini, including 132 hypogean and 8 epigean species. Our results showed that the overall morphological variation of cave carabids has gradually specialized from an anophthalmic to semi-aphaenopsian to aphaenopsian type. There were extremely significant differences (p < 0.01) among four different adaptive types including aphaenopsian, semi-aphaenopsian, anophthalmic, and surface-dwelling Trechini when their adaptability to a cave environment was used as the basis for grouping. Furthermore, there were differences in the phenotypic tree of the head, pronotum, and elytra, and an integrated morphology. To the best of our knowledge, this is the first report on the analysis of the head, pronotum, and elytra of four different adaptive types of ground beetles in order to clarify the morphological adaptations of cavernicolous carabids to the cave environment.


2021 ◽  
Vol 8 ◽  
Author(s):  
Liyan Zhang ◽  
Jing Zhang ◽  
Shigang Liu ◽  
Rui Wang ◽  
Jiali Xiang ◽  
...  

The Ninety East Ridge is a submarine north–south oriented volcanic ridge in the eastern Indian Ocean. Surface-layer ichthyoplankton collected in this area from September to October were identified by combined morphological and molecular (DNA barcoding) techniques, and their species composition, diversity, and abundance, and correlations with environmental variables were described. Collections comprised 109 larvae and 507 eggs, which were identified to 37 taxa in 7 orders, 20 families, and 27 genera, and were dominated by the order Perciformes and species Vinciguerria sp., Oxyporhamphus micropterus, and Decapterus macarellus. Species abundances at each station and of each species were relatively low, suggesting that this area or the time of sampling were not of major importance for fish spawning. Waters above Ninety East Ridge had lower species diversity but higher species richness than waters further offshore. A generalized additive model revealed that high abundance of ichthyoplanktonic taxa occurred in areas with low sea surface height and high sea surface salinity, temperature, and chlorophyll a concentration. Of these, sea surface height was most correlated with ichthyoplankton abundance. We provided baseline data on surface-dwelling ichthyoplankton communities in this area to aid in development of pelagic fishery resources in waters around the Ninety East Ridge.


Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 487
Author(s):  
David C. Culver ◽  
Louis Deharveng ◽  
Tanja Pipan ◽  
Anne Bedos

Riding a wave of interest in biodiversity patterns in surface-dwelling communities, in 2000, Culver and Sket [1] published a paper listing 20 caves and karst wells with 20 or more known species. [...]


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