Describing the Ionoregulatory Changes that Underlie Cold Acclimation in Drosophila Melanogaster

At low temperatures Drosophila lose the ability to regulate ion and water balance across the gut leading to a lethal accumulation of K+ in the haemolymph (hyperkalemia). Cold-acclimation can mitigate these ion imbalances, but the physiological mechanisms that facilitate this process are still not understood. Upon adult emergence, D. melanogaster females were subjected to seven days at 25C (warm-acclimation) or 10C (cold-acclimation). Cold-acclimation reduced the critical thermal minimum (CTmin), sped up recovery from chill coma, improved survival following cold stress, and mitigated cold-induced hyperkalemia. In parallel, cold-acclimated flies experienced increased Malpighian tubule fluid and K+ secretion and reduced rectal K+ reabsorption. These changes were independent of Na+/K+- or V-type H+-ATPases. These results suggest that modification of Malpighian tubule and gut mitigate cold-induced hyperkalemia. Additionally, I present preliminary findings on the effects of acclimation, sex, and blood-feeding on the cold tolerance of the arboviral disease vector mosquito, A. aegypti

The effect of cold acclimation on active ion transport in cricket ionoregulatory tissues.

Cold-acclimated insects defend ion and water transport function during cold exposure. We hypothesized that this is achieved via enhanced active transport. The Malpighian tubules and rectum are likely targets for such transport modifications, and recent transcriptomic studies indicate shifts in Na+-K+ ATPase (NKA) and V-ATPase expression in these tissues following cold acclimation. Here we quantify the effect of cold acclimation (one week at 12 °C) on active transport in the ionoregulatory organs of adult Gryllus pennsylvanicus field crickets. We compared primary urine production of warm- and cold-acclimated crickets in excised Malpighian tubules via Ramsay assay at a range of temperatures between 4 and 25 °C. We then compared NKA and V-ATPase activities in Malpighian tubule and rectal homogenates from warm- and cold-acclimated crickets via NADH-linked photometric assays. Malpighian tubules of cold-acclimated crickets excreted fluid at lower rates at all temperatures compared to warm-acclimated crickets. This reduction in Malpighian tubule excretion rates may be attributed to increased NKA activity that we observed for cold-acclimated crickets, but V-ATPase activity was unchanged. Cold acclimation had no effect on rectal NKA activity at either 21 °C or 6 °C, and did not modify rectal V-ATPase activity. Our results suggest that an overall reduction, rather than enhancement of active transport in the Malpighian tubules allows crickets to maintain hemolymph water balance during cold exposure, and increased Malpighian tubule NKA activity may help to defend and/or re-establish ion homeostasis

HCG (1500IU) administration on day 3 after oocytes retrieval, following GnRH-agonist trigger for final follicular maturation, results in high sufficient mid luteal progesterone levels - a proof of concept

BACKGROUND: Controlled ovarian hyperstimulation (COH) which combining GnRH antagonist co-treatment and GnRH agonist trigger with an additional 1500 IU hCG luteal rescue on day of oocytes retrieval, has become a common tool aiming to reduce severe ovarian hyperstimulation syndrome (OHSS). In the present, proof of concept study, we evaluate whether by deferring the hCG rescue bolus for 3 days, we are still able to rescue the luteal phase. METHODS: Patients undergoing the GnRH-antagonist protocol, who were considered at high risk for developing severe OHSS and received GnRH-agonist for final oocyte maturation, were included. For luteal phase support, all patients received an “intense” luteal support. Those who had no signs of early moderate OHSS on day 3 after oocytes retrieval were instructed to inject 1500 IU of HCG bolus (hCG group). Ovarian stimulation characteristics and mid luteal progesterone levels were compared between those who received the HCG bolus and those who did not. RESULTS: Eleven IVF cycles were evaluated, 5 in the hCG group and 6 in the intense luteal support only group. While no in-between group differences were observed in ovarian stimulation characteristics, significantly higher mid luteal progesterone levels (>127 nmol/L vs 42.1 ± 14.5 nmol/L, respectively) and a non-significant increase in pregnancy rate (40% vs 16.6%, respectively), were observed in those who receive the hCG bolus compared to those who did not. CONCLUSIONS: hCG luteal rescue should be offered 3 days after oocytes retrieval only to those patients with no signs of early moderate OHSS. Further studies are required to elucidate the appropriate regimen of luteal HCG administration in patients undergoing final follicular maturation with GnRH-agonist

Gene-Gene Interactions Lead to Higher Risk for Development of Type 2 Diabetes in an Ashkenazi Jewish Population

Evidence has accumulated that multiple genetic and environmental factors play important roles in determining susceptibility to type 2 diabetes (T2D). Although variants from candidate genes have become prime targets for genetic analysis, few studies have considered their interplay. Our goal was to evaluate interactions among SNPs within genes frequently identified as associated with T2D.Logistic regression was used to study interactions among 4 SNPs, one each from HNF4A[rs1884613], TCF7L2[rs12255372], WFS1[rs10010131], and KCNJ11[rs5219] in a case-control Ashkenazi sample of 974 diabetic subjects and 896 controls. Nonparametric multifactor dimensionality reduction (MDR) and generalized MDR (GMDR) were used to confirm findings from the logistic regression analysis. HNF4A and WFS1 SNPs were associated with T2D in logistic regression analyses [P<0.0001, P<0.0002, respectively]. Interaction between these SNPs were also strong using parametric or nonparametric methods: the unadjusted odds of being affected with T2D was 3 times greater in subjects with the HNF4A and WFS1 risk alleles than those without either (95% CI = [1.7-5.3]; P<or=0.0001). Although the univariate association between the TCF7L2 SNP and T2D was relatively modest [P = 0.02], when paired with the HNF4A SNP, the OR for subjects with risk alleles in both SNPs was 2.4 [95% CI = 1.7-3.4; P<or=0.0001]. The KCNJ11 variant reached significance only when paired with either the HNF4A or WFSI SNPs: unadjusted ORs were 2.0 [95% CI = 1.4-2.8; P<or=0.0001] and 2.3 [95% CI = 1.2-4.4; P<or=0.0001], respectively. MDR and GMDR results were consistent with the parametric findings.These results provide evidence of strong independent associations between T2D and SNPs in HNF4A and WFS1 and their interaction in our Ashkenazi sample. We also observed an interaction in the nonparametric analysis between the HNF4A and KCNJ11 SNPs (P<or=0.001), demonstrating that an independently non-significant variant may interact with another variant resulting in an increased disease risk

Cell Free Expression of hif1α and p21 in Maternal Peripheral Blood as a Marker for Preeclampsia and Fetal Growth Restriction

Preeclampsia, a severe unpredictable complication of pregnancy, occurs in 6% of pregnancies, usually in the second or third trimester. The specific etiology of preeclampsia remains unclear, although the pathophysiological hallmark of this condition appears to be an inadequate blood supply to the placenta. As a result of the impaired placental blood flow, intrauterine growth restriction (IUGR) and consequential fetal oxidative stress may occur. Consistent with this view, pregnancies complicated by preeclampsia and IUGR are characterized by up-regulation of key transcriptional regulators of the hypoxic response including, hif1α and as well as p53 and its target genes. Recently, the presence of circulating cell-free fetal RNA has been documented in maternal plasma. We speculated that pregnancies complicated by preeclampsia and IUGR, will be associated with an abnormal expression of p53 and/or hif1α related genes in the maternal plasma. Maternal plasma from 113 singleton pregnancies (72 normal and 41 complicated pregnancies) and 19 twins (9 normal and 10 complicated pregnancies) were collected and cell free RNA was extracted. The expression of 18 genes was measured by one step real-time RT-PCR and was analyzed for prevalence of positive/negative expression levels. Results indicate that, among the genes examined, cell free plasma expressions of p21 and hif1α were more prevalent in pregnancies complicated by hypoxia and/or IUGR (p<0.001). To conclude, we present in this manuscript data to support the association between two possible surrogate markers of hypoxia and common complications of pregnancy. More work is needed in order to implement these findings in clinical practice

Maple Tree Adult and Sapling Data collected at York University

<p>Data was collected from the Danby Woods forest at York University's Keele campus. Researchers analyzed 10 Maple trees and their nearest sapling and recorded 4 variables which included dbh, % canopy coverage, distance to sapling, and dbh of sapling. Diameter at breast height (dbh) and sapling dbh ware measured in cm using a measuring tape and were recorded to the nearest 0.1 cm. Canopy coverage was estimated using hands to create a small square in the sky from which the percent coverage could be estimated. Finally, distance to the nearest sapling was measured in metres from the centre of the adult trunk to the sapling trunk. Saplings were defined as trees that were no higher than approximetly double the height of an average student.</p

Distance Based Sampling of Birds at York University’s Keele Campus

<p>Distance based sampling was used to survey bird species at the Danby Forest at York University. 25m belt transects were set in 5 locations in the woodlot and 5 locations in the adjacent grassland. The researcher walked along the transect and observed the surrounding area for birds. Data for sighted birds included frequency of species, bird's common name, wind speed and estimated distance to the bird. Frequency of species was recorded by counting number of birds that were together in a group. The common name of the bird was determined by observing the bird's morphology and with reference to a bird guide. Wind speed was recorded using the Beaufort scale which divides wind speed into 13 different categories from 0 (no wind) to 12 (strongest winds).</p