Anti-oxidative enzyme changes associated with chickpea calli tolerant to Ascochyta rabiei culture filtrate.

Ascochyta blight caused by Ascochyta rabiei (Pass.) Labrousse is a major biotic constraint in production of chickpea. In the present investigation, all chickpea genotypes [E100Y (m), Gaurav, Pb-7 and L550] induced 100% callus on standard medium with greenish colour and fragile structure. These calli were used for in vitro screening against pathogen, A. rabiei culture filtrate at 0, 5, 10, 15 and 20% concentrations. Survival rate of calli in all chickpea's genotypes were reduced significantly at higher concentration (15%) of culture filtrate. The culture filtrate concentration of 20 % was lethal for calli of all chickpea's genotypes. Hence, biochemical changes viz. total soluble proteins and activities of anti-oxidative enzymes (polyphenol oxidase, peroxidase and catalase) were estimated at 15% and below concentration of culture filtrate. Tolerant calli of resistant genotype, E100 Y (m) revealed significantly higher total soluble proteins (10.04 mg g⁻¹ f.wt. of callus) and activity of anti-oxidative enzymes, polyphenol oxidase (9.0 unit absorbance change min⁻¹ mg⁻¹ protein) and peroxidase (19.09 unit absorbance change min⁻¹ mg⁻¹ protein) and lower catalase (18.65 µ moles of H2O2 utilized min⁻¹ mg⁻¹ protein) at higher (15%) concentration of culture filtrate followed by moderately resistant (Gaurav), and susceptible genotypes (Pb-7 and L550). Thus, higher polyphenol oxidase and peroxidase and lower catalase activity in chickpea's genotypes against culture filtrate of A. rabiei could be used as parameters for screening resistant genotypes to pathogen, A. rabiei.

Established and new mouse models reveal E2f1 and Cdk2 dependency of retinoblastoma, and expose effective strategies to block tumor initiation.

RB(+/-) individuals develop retinoblastoma and, subsequently, many other tumors. The Rb relatives p107 and p130 protect the tumor-resistant Rb(-/-) mouse retina. Determining the mechanism underlying this tumor suppressor function may expose novel strategies to block Rb pathway cancers. p107/p130 are best known as E2f inhibitors, but here we implicate E2f-independent Cdk2 inhibition as the critical p107 tumor suppressor function in vivo. Like p107 loss, deleting p27 or inactivating its Cdk inhibitor (CKI) function (p27(CK-)) cooperated with Rb loss to induce retinoblastoma. Genetically, p107 behaved like a CKI because inactivating Rb and one allele each of p27 and p107 was tumorigenic. Although Rb loss induced canonical E2f targets, unexpectedly p107 loss did not further induce these genes, but instead caused post-transcriptional Skp2 induction and Cdk2 activation. Strikingly, Cdk2 activity correlated with tumor penetrance across all the retinoblastoma models. Therefore, Rb restrains E2f, but p107 inhibits cross talk to Cdk. While removing either E2f2 or E2f3 genes had little effect, removing only one E2f1 allele blocked tumorigenesis. More importantly, exposing retinoblastoma-prone fetuses to small molecule inhibitors of E2f (HLM006474) or Cdk (R547) for merely 1 week dramatically inhibited subsequent tumorigenesis in adult mice. Protection was achieved without disrupting normal proliferation. Thus, exquisite sensitivity of the cell-of-origin to E2f and Cdk activity can be exploited to prevent Rb pathway-induced cancer in vivo without perturbing normal cell division. These data suggest that E2f inhibitors, never before tested in vivo, or CKIs, largely disappointing as therapeutics, may be effective preventive agents.

Incidentally detected squamous cell carcinoma in non-functioning kidney presenting as multi-cystic mass.

Squamous cell carcinoma (SCC) of urinary tract is a rarely encountered tumor. The incidence of this tumor is 1.4 per cent of all renal malignancies (1). We present a case of 52 years male with squamous cell carcinoma of renal pelvis, presenting as chronic pyelonephritis transforming the kidney into non-functioning multicystic cavitatory mass without any renal calculi. The case highlights the rarity of tumor in absence of calculi or any other predisposing factor. Moreover, histology of resected specimen detected features of SCC giving importance to careful and exhaustive assessment of specimen and of histologic sections, when there is no suspicion of malignancy clinically.