SUMMARY Eurythermal ectotherms commonly thrive in environments that expose them to large variations temperature on daily and seasonal bases. The roles played by alterations gene expression enabling eurytherms adjust these two temporally distinct patterns of thermal stress are poorly understood. We used cDNA microarray analysis examine changes a eurythermal fish, Austrofundulus limnaeus, subjected long-term acclimation constant temperatures 20, 26 37°C environmentally realistic fluctuations...

Diapausing embryos of Austrofundulus limnaeus survive desiccating conditions by reducing evaporative water loss. Over 40% diapause II 113 days exposure to 75.5% relative humidity. An early loss from the perivitelline space occurs during 1–2, but thereafter, rates are reduced near zero. No dehydration embryonic tissue is indicated based on microscopic observations and retention bulk (freezable) in as judged differential scanning calorimetry. Such high resistance desiccation unprecedented...

The annual killifish Austrofundulus limnaeus inhabits ephemeral ponds that dry out on a seasonal basis, thereby killing the adult and juvenile forms. Populations persist because diapausing embryos become embedded in pond sediments. rate of oxygen consumption diapause II is depressed by up to 90 % compared with developing embryos, parallel reduction observed heart rate. Developmental arrest was identified cessation somite proliferation blockage ontogenetic increase DNA content. Surprisingly,...

SUMMARY The annual killifish Austrofundulus limnaeus survives in ephemeral pond habitats by producing drought-tolerant diapausing embryos. These embryos probably experience oxygen deprivation as part of their normal developmental environment. We assessed the anoxia tolerance A. across duration embryonic development. Embryos develop a substantial to during early development, which peaks diapause II. This extreme is retained first 4 days post-diapause II development and then lost. Metabolism...

Embryos of the annual killifish Austrofundulus limnaeus enter a state developmental arrest termed diapause as part their normal program. Diapause can occur at two distinct stages in this species, II and III. When incubated 25°C, most embryos II, whereas small percentage 'escape' develop continuously past Control entry into be altered by maternal influences incubation environment experienced embryos. Young females produce higher proportion escape than do older females. In addition, increasing...

Course-based undergraduate research experiences (CUREs) and inquiry-based curricula both expose students to the scientific process. CUREs additionally engage in novel scientifically relevant research, with intention of providing an "authentic" experience. However, we have little understanding which course design elements impact students' beliefs that they are experiencing research. We designed a study explore introductory biology perceptions authenticity CURE inquiry classes. Using...

Genotype and environment can interact during development to produce novel adaptive traits that support life in extreme conditions. The of the annual killifish Austrofundulus limnaeus is unique among vertebrates because embryos have distinct cell movements separate epiboly from axis formation early development, enter into a state metabolic dormancy known as diapause survive environmental ability be maternally programmed, with young females producing do not diapause. Alternately, programmed...

The mechanisms that integrate environmental signals into developmental programs remain largely uncharacterized. Nuclear receptors (NRs) are ligand-regulated transcription factors orchestrate the expression of complex phenotypes. vitamin D receptor (VDR) is an NR activated by 1α,25-dihydroxyvitamin 3 [1,25(OH) 2 ], a hormone derived from 7-dehydrocholesterol (7-DHC). VDR signaling best known for regulating calcium homeostasis in mammals, but recent evidence suggests diversity uncharacterized...

Behavioral thermoregulation can allow ectotherms to buffer the effects of changes in environmental temperature, and thus an organism's preferred temperature is thought be under strong selection. However, this contention has seldom been tested. We used common killifish Fundulus heteroclitus from high‐latitude (northern) low‐latitude (southern) populations investigate intraspecific variation thermal preference its relationship habitat temperature. quantified temperatures northern southern...

Austrofundulus limnaeus is an annual killifish from the Maracaibo basin of Venezuela. Annual killifishes are unique among vertebrates in their ability to enter into a state dormancy at up three distinct developmental stages termed diapause I, II, and III. These embryos tolerant wide variety environmental stresses develop relatively slowly compared with nonannual fishes.These traits make them excellent model for research on interactions between genome environment during development, choice...

Background: Extreme anoxia tolerance requires a metabolic depression whose modulation could involve small non-coding RNAs (small ncRNAs), which are specific, rapid, and reversible regulators of gene expression. A previous study sncRNA expression in embryos the annual killifish Austrofundulus limnaeus, most anoxia-tolerant vertebrate known, revealed specific pattern sncRNAs that play important roles tolerance. Here, we conduct comparative on presence ncRNAs representatives several major...

The annual killifish Austrofundulus limnaeus inhabits ephemeral ponds in northern Venezuela, South America, and is an emerging extremophile model for vertebrate diapause, stress tolerance, evolution. Embryos of A. regularly experience extended periods desiccation anoxia as a part their natural history have unique metabolic developmental adaptations. Currently, there are limited genomic resources available gene expression evolutionary studies that can take advantage system. We describe the...

Rates of protein synthesis are substantially depressed in diapause II embryos Austrofundulus limnaeus. Inhibition oxygen consumption and heat dissipation with cycloheximide indicates that 36% the adenosine triphosphate (ATP) turnover prediapausing (8 d postfertilization [dpf]) is caused by synthesis; contribution to ATP negligible. In agreement metabolic data, incorporation amino acids (radiolabeled via 14CO2) into perchloric acid–precipitable decreases over 93% compared at 8 dpf. This...