Amplification and quantification of cold-associated microRNAs in the Colorado potato beetle (Leptinotarsa decemlineata) agricultural pest.

The Colorado potato beetle [Leptinotarsa decemlineata (Say)] is an important insect pest that can inflict considerable damage to potato plants. This insect can survive extended periods of cold exposure, and yet the molecular switches underlying this phenomenon have not been fully elucidated. A better characterization of this process would highlight novel vulnerabilities associated with L. decemlineata that could serve as targets for the management of this devastating pest. Using high-throughput sequencing, the current work reveals a cold-associated signature group of microRNAs (miRNAs) in control (15 °C) and -5 °C-exposed L. decemlineata. The results show 42 differentially expressed miRNAs following cold exposure including miR-9a-3p, miR-210-3p, miR-276-5p and miR-277-3p. Functional analysis of predicted targets associated with these cold-responsive miRNAs notably linked these changes with vital metabolic and cellular processes. Overall, this study highlights the miRNAs probably responsible for facilitating cold adaptation in L. decemlineata and implicates miRNAs as a key molecular target to consider in the development of novel pest management strategies against these insects.

Characterization of miRNAs modulated by torpor in the hibernating ground squirrel Ictidomys tridecemlineatus liver by next-generation sequencing.

BACKGROUND: Mammalian hibernation is a fascinating phenomenon that involves multiple molecular and biochemical changes to proceed. While the molecular picture associated with torpor has become clearer in recent years, the function of non-coding RNAs, and especially of microRNAs, solicited during this process is not well understood. OBJECTIVE: To better characterize a signature of cold torpor-associated miRNAs in the hibernating thirteen-lined ground squirrel Ictidomys tridecemlineatus. MATERIALS AND METHODS: Next-generation sequencing and qRT-PCR approaches were conducted in euthermic and hibernating ground squirrel liver tissues. RESULTS: This high-throughput approach notably revealed modulation during hibernation of various miRNAs previously associated with lipid metabolism, glucose metabolism and antioxidant responses such as miR-145a-3p, miR-22-3p and miR-25-3p, respectively. CONCLUSION: Overall, these results present a group of miRNAs differentially expressed in hibernating ground squirrel liver and provide additional knowledge on the underlying functions of these small non-coding molecules during cold torpor.

Identification of differentially regulated micrornas in cold-hardy insects.

Freeze tolerance in insects is associated with cryoprotectant synthesis and strong metabolic suppression. Freeze avoidance, an alternative strategy in cold-hardy insects, is also characterized by hypometabolism, but possesses significant cellular and physiological differences when compared with freeze tolerance. We hypothesized that microRNAs, non-coding transcripts that bind to mRNA, could play a role in the regulation of energy-expensive mRNA translation in insects exposed to low temperatures. Expression levels of microRNA species were evaluated during cold acclimation of freeze tolerant Eurosta solidaginis and freeze-avoiding Epiblema scudderiana, comparing control (5 degree C) conditions with larvae given sequential exposures to -5 degree C and -15 degree C. MiR-1 levels were significantly elevated in frozen E. solidaginis larvae at -15 degree C, whereas miR-34 levels were unchanged. MiR-1 and miR-34 levels remained stable in E. scudderiana. These data demonstrate differential microRNA expression in frozen versus control insect larvae and highlight contrasting microRNA signatures between freeze tolerant and freeze avoiding species.

Regulation of adipogenesis by a transcriptional repressor that modulates MAPK activation.

Mitogen-activated protein kinase (MAPK) is required for cell growth and cell differentiation. In adipogenesis, MAPK activation opposes the differentiation process. The regulatory mechanisms or the cellular factors that regulate the switch between growth and differentiation in the adipogenic lineage have been largely unelucidated. We show here that AEBP1, a transcriptional repressor that is down-regulated during adipogenesis, complexes and protects MAPK from its specific phosphatase in mammalian cells. We further show evidence that the modulation of MAPK activation by AEBP1 is a biologically relevant process in adipogenesis. Our results suggest that modulation of MAPK activation by the protective effect of AEBP1 may constitute a critical part in the determination between cell growth and differentiation in the adipogenic lineage. The proposed mode of action by which a transcription factor regulates MAPK activation is novel.

The effect of renal transplantation on plasma protein binding.

The in vitro plasma protein binding was determined in nine maintenance hemodialysis patients who later underwent renal transplantation. The organic acid fluorescein (10 micrograms/ml) or the organic base quinidine (5 micrograms/ml) was added to the pre and post transplant serum of these patients. Drug concentrations were measured spectrophotofluorometrically after equilibrium dialysis. The results were compared with the plasma protein binding of eight normal volunteers. The patients on maintenance hemodialysis had lower plasma protein binding of fluorescein than normals (78 +/- 5% vs 89 +/- 4, p less than 0.001). Plasma protein binding improved significantly after renal transplantation (85 +/- 3, p less than 0.01) but was still lower than in normals (p 0.05). Plasma protein binding of quinidine was not significantly different than in normal volunteers (77 +/- 8%) either prior to (72 +/- 10%) or after (73 +/- 12%) kidney transplantation. Plasma protein binding of quinidine remains unaffected by renal transplantation. However, the abnormal plasma protein binding or organic acids in chronic renal failure may be significantly improved by renal transplantation.

Association of graft survival with host response to hepatitis B infection in patients with kidney transplants.

We studied the relation of host response to hepatitis B infection before transplantation with survival of kidney grafts in 79 patients receiving 87 transplants. Antibody to hepatitis B surface antigen (anti-HBs) signaled early graft rejection (median survival congruent to two months), whereas hepatitis B surface antigen (HBsAg) signaled delayed rejection (greater than 22 months). Patients with neither HBsAg nor anti-HBs had graft survival times (median congruent to 16 months) similar to the HBsAg carriers but significantly longer than the anti-HBs-positive patients (p less than 0.01). Similar results were observed when patients who received HLA-identical kidneys or had anti-HLA antibodies before transplantation were excluded. The highest probability of graft rejection was in patients with anti-HBs who received kidneys from male donors. The probability that such grafts would survive for four months was less than 20 per cent. HLA-nonidentical kidneys transplanted into patients with anti-HBs have a poor prognosis, whereas such grafts in HBsAg carriers have as good a prognosis as grafts in uninfected recipients.