Divergence of the diapause transcriptome in apple maggot flies: winter regulation and post-winter transcriptional repression

Citation: Meyers, P. J., Powell, T. H. Q., Walden, K. K. O., Schieferecke, A. J., Feder, J. L., Hahn, D. A., . . . Ragland, G. J. (2016). Divergence of the diapause transcriptome in apple maggot flies: winter regulation and post-winter transcriptional repression. Journal of Experimental Biology, 219(17), 2613-2622. doi:10.1242/jeb.140566The duration of dormancy regulates seasonal timing in many organisms and may be modulated by day length and temperature. Though photoperiodic modulation has been well studied, temperature modulation of dormancy has received less attention. Here, we leverage genetic variation in diapause in the apple maggot fly, Rhagoletis pomonella, to test whether gene expression during winter or following spring warming regulates diapause duration. We used RNAseq to compare transcript abundance during and after simulated winter between an apple-infesting population and a hawthorn-infesting population where the apple population ends pupal diapause earlier than the hawthorn-infesting population. Marked differences in transcription between the two populations during winter suggests that the 'early' apple population is developmentally advanced compared with the 'late' hawthorn population prior to spring warming, with transcripts participating in growth and developmental processes relatively up-regulated in apple pupae during the winter cold period. Thus, regulatory differences during winter ultimately drive phenological differences that manifest themselves in the following summer. Expression and polymorphism analysis identify candidate genes in the Wnt and insulin signaling pathways that contribute to population differences in seasonality. Both populations remained in diapause and displayed a pattern of up-and then down-regulation (or vice versa) of growth-related transcripts following warming, consistent with transcriptional repression. The ability to repress growth stimulated by permissive temperatures is likely critical to avoid mismatched phenology and excessive metabolic demand. Compared with diapause studies in other insects, our results suggest some overlap in candidate genes/pathways, though the timing and direction of changes in transcription are likely species specific

Data from: Ovary development and cold tolerance of the invasive pest Drosophila suzukii (Matsumura) in the central plains of Kansas, United States

Environmental challenges presented by temperature variation can be overcome through phenotypic plasticity in small invasive ectotherms. We tested the effect of thermal exposure to 21, 18, and 11°C throughout the whole life cycle of individuals, thermal exposure of adults reared at 25°C to 15 and 11°C for a 21-d period, and long (14:10 hr) and short (10:14 hr) photoperiod on ovary size and development in Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) cultured from a recently established population in Topeka, Kansas (United States). Examination of the response to temperature and photoperiod variation in this central plains population provides insight into the role of phenotypic plasticity in a climate that is warmer than regions in North America where D. suzukii was initially established. We found both low temperature and short photoperiod resulted in reduced ovary size and level of development. In particular, reduced ovary development was observed following exposure to 15°C, indicating that ovary development in females from the central plains population is more sensitive to lower temperature compared with populations examined from the northern United States and southern Canada. We also provide evidence that D. suzukii reared at 25°C are capable of short-term hardening when exposed to −6°C following 4°C acclimation, contrary to previous reports indicating flies reared at warm temperatures do not rapidly-cold harden. Our study highlights the central role of phenotypic plasticity in response to winter-like laboratory conditions and provides an important geographic comparison to previously published assessments of ovary development and short-term hardening survival response for D. suzukii collected in cooler climates

Ovary and Cold Tolerance D. suzukii Data

A spreadsheet containing ovary dimensional sizes and stages of development for D. suzukii samples in different rearing/temperature conditions

<i>Kiluluma ceratotherii</i> (Nematoda: Strongylida) in a White Rhinoceros (<i>Ceratotherium simum</i>) from the United States: Case Report

Nematodes of the genus Kiluluma (Strongylidae, Cyathostominae) parasitize African rhinoceros. We describe the case of a one-year-old male white rhinoceros calf that presented with colonic inflammation and hemorrhage at necropsy. The animal had died following a neurological episode. We recovered and identified adult nematodes from the colon using morphology and ITS2 gene sequences as Kiluluma ceratotherii. We also generated nuclear ITS1, 5.8S, ITS2, and mitochondrial cox1 sequences for future studies and deposited them in GenBank (OR142644–OR142653). Since the animal was born in the same zoo and never transported, infection likely originated within the herd. This is the first report of this nematode from a white rhinoceros in the United States

BENTHIC MICROPLASTIC DISTRIBUTION IN HUMBOLDT BAY, NORTHERN CALIFORNIA: A COMPARATIVE STUDY OF SURFACE SEDIMENTS BASED ON PROXIMITY FROM THE SHORE

https://digitalcommons.humboldt.edu/inrsep_posters/1019/thumbnail.jp