Molecular characterization of Indian potato (Solanum tuberosum L.) varieties for cold-induced sweetening using SSR markers

Cold-induced sweetening developed during storage of potatoes (Solanum tuberosum L.) at low temperature is a crucial factor influencing the processing quality of potato tubers and remains one of the principal concerns of potato processing industry. Developing CIS-resistant genotypes is the most effective method to cope with this stress. In this study, the genetic diversity of 11 Indian potato varieties with different reactions to CIS was assessed using 10 SSR primers. The primers detected a total of 42 alleles arranged in 44 different configurations, among which 37 alleles (88%) were polymorphic. The polymorphic information content (PIC) value of the SSR locus ranged from 0.473 to 0.787 thus indicating a high utility of these markers for study of genetic diversity in potato. A number of polymorphic fragments appeared to be specific to a given sugar-forming group. Primer Sti007 generated one fragment Sti007131bp present only in all the high sugar-forming varieties. The dendrogram derived from Dice’s similarity coefficients among the 11 varieties could partially but efficiently differentiate close parents and sugar-forming groups among the varieties. These findings demonstrate the effectiveness of SSR markers to assess the genetic variation among potato cultivars in order to develop molecular markers associated with CIS to improve potato breeding programs

Mechanisms of prostate cancer metastasis induced by Stat5a/b signaling

The majority of prostate cancer-related deaths are due to metastatic progression, a process that is poorly understood. Active Stat5a/b predicts early disease recurrence in clinical prostate cancer, which typically manifests as development of metastatic disease. The focus of this thesis was to investigate the significance and underlying mechanisms of active Jak2-Stat5a/b signaling in metastatic dissemination of prostate cancer. The work presented here provides mechanistic evidence that active Stat5a/b promotes Epithelial-to-Mesenchymal Transition (EMT) of prostate cancer cells as indicated by increased Twist1, N-cadherin, vimentin, and fibronectin expression, while E-cadherin levels were down-regulated. Inhibition of Jak2-Stat5a/b signaling suppressed the molecular changes associated with active Stat5a/b-induced EMT in prostate cancer cells, in prostate cancer xenograft tumors, and patient-derived clinical prostate cancers. Induction of Jak2-Stat5a/b signaling disrupted epithelial monolayer of prostate cancer cells while inducing migration and adhesion of prostate cells to fibronectin. Furthermore, the work presented here demonstrates that transcription factor Twist1 is a mediator of prostate cancer EMT induced by Jak2-Stat5a/b. Specifically, Twist1 knockdown blocked functional endpoints of EMT induced by Jak2-Stat5a/b and suppressed Jak2-Stat5a/b-induced changes in the expression of EMT markers which was rescued by re-introduction of Twist1. Unexpectedly, while promoting EMT, Jak2-Stat5a/b signaling induced stem-like properties in prostate cancer cells including sphere formation and expression of stemness markers such as BMI1. Mechanistically, both Twist1 and BMI1 were critical for Stat5a/b induction of stem-like features as genetic knockdown of Twist1 suppressed Stat5a/b-induced BMI1 expression and sphere formation in stem cell culture conditions, which was rescued by re-introduction of BMI1. Using human prolactin knock-in mice, we demonstrate that Jak2-Stat5a/b signaling promoted metastases formation of prostate cancer cells in vivo. Collectively, this work implicates that active Jak2-Stat5a/b promotes metastatic dissemination of prostate cancer by inducing EMT and stem-like properties of prostate cancer cells

Seed storage proteins as a protein marker for identification and characterization of QPM and normal maize inbred lines

Twenty maize inbreds has been studied through seed storage protein markers for approaching characterization among three groups of maize inbreds viz., low, intermediate and high lysine and tryptophan containing QPM and normal lines. SDS-PAGE of protein fractions showed variation into the three groups of maize inbreds. When comparing four fractions of total soluble proteins, they exhibit a range of variable bands some polypeptides were specifically express in QPM lines, could group the maize lines into two main clusters, QPM and normal maize lines. From these findings, it can be concluded that, the newly separated polypeptide protein bands could be used as a biochemical protein marker which indirectly help for the selection and development of QPM maize inbred lines. Thus, electrophoresis of protein fractions is useful to differentiate QPM and normal inbred lines based on variation in banding pattern

Profiling of StvacINV1, BAM1 and INH2α expressions in relation to acid invertase and β-Amylase activities during development of cold-induced sweetening in Indian potato (Solanum tuberosum L.) tubers

Cold-induced sweetening (CIS) characterized by reducing sugars (RS) accumulation during low temperature storage of potato (Solanum tuberosum L.) tubers remains a serious postharvest concern for the potato processing industry. Enzymes involved in carbohydrates metabolism and the genes modulating their activities are of paramount importance in the events associated with the development of CIS. Expression of vacuolar acid invertase gene StvacINV1, β-amylase gene BAM1 and invertase inhibitor gene INH2α and their consequence on acid invertase and β-amylase activities with resulting RS accumulation were followed in one CIS-tolerant (Kufri Jyoti) and one CIS-susceptible (Kufri Badshah) Indian potato varieties stored in cold conditions. Differential gene expression analysis showed that during cold storage, expression of StvacINV1 and BAM1 increased at low temperature and their transcripts were more expressed in the CIS-tolerant variety than the CIS-sensitive. Besides, correlation between BAM1 expression and β-amylase activity affirmed the hypothesis of several enzymes and pathways involved in starch degradation during cold storage of potato. Expression of invertase inhibitor gene INH2α however was higher in the CIS-tolerant variety than the CIS-sensitive. Correlating StvacINV1 and INH2α expressions with RS content and acid invertase activity established that post-translational regulation of acid invertase by the invertase inhibitor protein could be an important component of resistance to CIS

Effect of storage temperature on carbohydrate metabolism and development of cold-induced sweetening in Indian potato ( Solanum Tuberosum L.) varieties

This study investigated the changes in carbohydrate metabolism in tubers of 11 Indian potato varieties stored at room temperature, 15C and 4C for 150 days to understand the development of cold-induced sweetening (CIS). Low-temperature storage negligibly influenced starch and maltose contents of the tubers but induced a significant increase of reducing sugars, total soluble sugars, fructose, glucose and hexoses : sucrose ratio, and a decrease of sucrose content was noticeable at 4C. A strong positive correlation was found between reducing sugars and total soluble sugars, and between fructose and glucose. The activity of β-amylase was considerably increased by storage at low temperature, and it weakly correlated with starch content. Also, the absence of maltose accumulation with increased β-amylase activity was observed. Acid invertase activity drastically rose at low temperature and strongly paralleled reducing sugars, glucose, fructose and hexose : sucrose ratio. The K. Jyoti variety was designated as CIS-tolerant and the K. Badshah variety as CIS-susceptibl

Inhibition of Stat5a/b Enhances Proteasomal Degradation of Androgen Receptor Liganded by Antiandrogens in Prostate Cancer.

Although poorly understood, androgen receptor (AR) signaling is sustained despite treatment of prostate cancer with antiandrogens and potentially underlies development of incurable castrate-resistant prostate cancer. However, therapies targeting the AR signaling axis eventually fail when prostate cancer progresses to the castrate-resistant stage. Stat5a/b, a candidate therapeutic target protein in prostate cancer, synergizes with AR to reciprocally enhance the signaling of both proteins. In this work, we demonstrate that Stat5a/b sequesters antiandrogen-liganded (MDV3100, bicalutamide, flutamide) AR in prostate cancer cells and protects it against proteasomal degradation in prostate cancer. Active Stat5a/b increased nuclear levels of both unliganded and antiandrogen-liganded AR, as demonstrated in prostate cancer cell lines, xenograft tumors, and clinical patient-derived prostate cancer samples. Physical interaction between Stat5a/b and AR in prostate cancer cells was mediated by the DNA-binding domain of Stat5a/b and the N-terminal domain of AR. Moreover, active Stat5a/b increased AR occupancy of the prostate-specific antigen promoter and AR-regulated gene expression in prostate cancer cells. Mechanistically, both Stat5a/b genetic knockdown and antiandrogen treatment induced proteasomal degradation of AR in prostate cancer cells, with combined inhibition of Stat5a/b and AR leading to maximal loss of AR protein and prostate cancer cell viability. Our results indicate that therapeutic targeting of AR in prostate cancer using antiandrogens may be substantially improved by targeting of Stat5a/b. Mol Cancer Ther; 14(3); 713-26. ©2014 AACR