Molecular cloning, expression and functional analysis of three subunits of protein phosphatase 2A (PP2A) from black tiger shrimps (Penaeus monodon)

Seasonal gene expression profiling of Antarctic krill in three different latitudinal regions

The Antarctic krill, Euphausia superba, has evolved seasonal rhythms of physiology and behaviour to survive under the extreme photoperiodic conditions in the Southern Ocean. However, the molecular mechanisms generating these rhythms remain far from understood. The aim of this study was to investigate seasonal differences in gene expression in three different latitudinal regions (South Georgia, South Orkneys/Bransfield Strait, Lazarev Sea) and to identify genes with potential regulatory roles in the seasonal life cycle of Antarctic krill. The RNA-seq data were analysed (a) for seasonal differences between summer and winter krill sampled from each region, and (b) for regional differences within each season. A large majority of genes showed an up-regulation in summer krill in all regions with respect to winter krill. However, seasonal differences in gene expression were less pronounced in Antarctic krill from South Georgia, most likely due to the milder seasonal conditions of the lower latitudes of this region, with a less extreme light regime and food availability between summer and winter. Our results suggest that in the South Orkneys/Bransfield Strait and Lazarev Sea region, Antarctic krill entered a state of metabolic depression and regressed development (winter quiescence) in winter. Moreover, seasonal gene expression signatures seem to be driven by a photoperiodic timing system that may adapt the flexible behaviour and physiology of Antarctic krill to the highly seasonal environment according to the latitudinal region. However, at the lower latitude South Georgia region, food availability might represent the main environmental cue influencing seasonal physiology.

Reprogramming factors induce proliferation and inhibit apoptosis of melanoma cells by changing the expression of particular genes

Uncontrolled proliferation and defective apoptosis are two major factors responsible for maintaining the malignant properties of melanoma cells. Our previous study demonstrated that induced expression of four reprogramming factors remodeled the phenotype of B16‑F10 mouse melanoma cells into melanoma stem cells. The present study was conducted to investigate the effect of the four Yamanaka reprogramming factors, namely Oct4, Sox2, Klf4 and c‑Myc (OSKM), on the proliferation and apoptosis of melanoma cells, and to identify the responsible molecular signals. The results identified that expression of the four reprogramming factors was highly induced by doxycycline treatment in the stable melanoma cell clone that was transfected with a plasmid expressing these factors, driven by the Tet‑On element. It was further confirmed that induced expression of these factors enhanced the proliferation and suppressed the apoptosis of the melanoma cells. In addition, induced OSKM expression increased cell proliferation, accelerated the progression of the cell cycle, and upregulated the mRNA expression levels of Janus kinase 2 (JAK2) and Cyclin‑B1. Induced expression of these factors also decreased the apoptosis, as well as upregulated B‑cell lymphoma 2 (BCL‑2) and downregulated BCL‑2‑associated X (BAX) mRNA expression levels. Taken together, the results suggested that upregulated JAK2 and Cyclin‑B1 may be responsible for the enhanced proliferation of melanoma cells, and that BCL‑2 upregulation and BAX downregulation may account for the suppressed apoptosis of these cells.

Transcriptome reveals involvement of immune defense, oxidative imbalance, and apoptosis in ammonia-stress response of the black tiger shrimp (Penaeus monodon)

Ammonia is a major aquatic environmental pollutant that negatively impacts shrimp health and commercial productivity. However, we currently do not fully understand the underlying molecular mechanisms of ammonia stress in shrimp. We therefore performed transcriptomic analysis of hepatopancreas from black tiger shrimp (Penaeus monodon) treated with ammonia-stress. We obtained 146,410,174 and 115,241,048 clean reads for the control and treatment groups, respectively. A total of 64,475 unigenes with an average length of 1275 bp and a N50 value of 2158 bp were assembled. A comparative transcriptome analysis identified 3462 differentially expressed genes, 177 of which are highly homologous with known proteins in aquatic species. Most of these genes showing the expression changes were related to immune function. Some significantly down-regulated genes are involved in purine metabolism and other metabolic pathways, which suggests that purineolytic capacity is an ammonia detoxification process in P. monodon, and metabolic depression is a strategy to reduce shrimp exposure to ammonia. Additionally, ammonia stress altered the expression patterns of key apoptosis genes (Bcl-xL, PERK, caspase 7, and caspase 10), confirmed that ammonia-stress induce oxidative stress and eventually even apoptosis. We also found evidence for the involvement of antioxidant defense in response to oxidative imbalance, given the regulation of peroxiredoxin 1, SOD, and CAT under ammonia stress. In conclusion, our study clarifies shrimp defensive response to ammonia toxicity and should benefit efforts to breed more ammonia-tolerant varieties.

Overexpression of microRNA-936 suppresses non-small cell lung cancer cell proliferation and invasion via targeting E2F2

MicroRNA (miR)-936 has been reported to inhibit the cell cycle and glioma cell proliferation. However, the roles of miR-936 in other human tumors remain largely unknown. In the present study, it was indicated that miR-936 was significantly downregulated in non-small cell lung cancer (NSCLC) tissues compared with adjacent normal tissues by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Results also indicated that miR-936 was downregulated in NSCLC cell lines compared with 16HBE cells. Furthermore, it was demonstrated that overexpression of miR-936 significantly inhibited the proliferation, cell cycle progression and invasion of NSCLC cells. Notably, E2F2 was identified as a target gene of miR-936 in NSCLC cells. The results indicated that E2F2 was upregulated in NSCLC tissues and cell lines, and its expression was negatively correlated with that of miR-936 in NSCLC tissues. Overexpression of miR-936 significantly reduced the protein expression levels of E2F2 in NSCLC cells. Furthermore, restoration of E2F2 rescued the proliferation and invasion of NSCLC cells transfected with miR-936 mimics. To the best of our knowledge, the present findings demonstrated for the first time that miR-936 suppressed NSCLC progression by directly targeting E2F2.

Circadian signaling in the Northern krill Meganyctiphanes norvegica: In silico prediction of the protein components of a putative clock system using a publicly accessible transcriptome

The Northern krill Meganyctiphanes norvegica is a significant component of the zooplankton community in many regions of the North Atlantic Ocean. In the areas it inhabits, M. norvegica is of great importance ecologically, as it is both a major consumer of phytoplankton/small zooplankton and is a primary food source for higher-level consumers. One behavior of significance for both feeding and predator avoidance in Meganyctiphanes is diel vertical migration (DVM), i.e., a rising from depth at dusk and a return to depth at dawn. In this and other euphausiids, an endogenous circadian pacemaker is thought, at least in part, to control DVM. Currently, there is no information concerning the identity of the genes/proteins that comprise the M. norvegica circadian system. In fact, there is little information concerning the molecular underpinnings of circadian rhythmicity in crustaceans generally. Here, a publicly accessible transcriptome was used to identify the molecular components of a putative Meganyctiphanes circadian system. A complete set of core clock proteins was deduced from the M. norvegica transcriptome (clock, cryptochrome 2, cycle, period and timeless), as was a large suite of proteins that likely function as modulators of the core clock (e.g., doubletime), or serves as inputs to it (cryptochrome 1) or outputs from it (pigment dispersing hormone). This is the first description of a "complete" (core clock through putative output pathway signals) euphausiid clock system, and as such, provides a foundation for initiating molecular investigations of circadian signaling in M. norvegica and other krill species, including how clock systems may regulate DVM and other behaviors.