Mechanism of DNA Double-Strand Break Repair

-- Kishore K Chiruvella,
Sritha K Sankaran, Monika Singh,
Mridula Nambiar and Sathees C Raghavan

DNA double-strand breaks (DSBs) are the most deleterious type of DNA damage. Failure in repair of DSBs may lead to chromosomal translocation and interstitial deletion, culminating in genomic instability and cancer. DSBs are generally repaired by two main pathways—Homologous Recombination (HR) and Nonhomologous DNA End Joining (NHEJ). HR predominantly occurs in lower organisms, requires extensive homology and is error-free. By contrast, NHEJ is the more common repair pathway in higher organisms such as humans and other mammals. NHEJ involves modification of the ends followed by joining using very little/no homology. In this review, the authors discuss the mechanism of HR and NHEJ-mediated joining of DSBs.

© 2007 IUP . All Rights Reserved.

Production of Cellulase and Laccase by Laccaria fraterna and Pleurotus ostreatus Under Submerged and Solid State Fermentation

-- K Balaraju, J Joel Gnanadoss,
S Arokiyaraj, P Agastian and V Kaviyarasan

Laccaria fraterna and Pleurotus ostreatus grow very well both in the submerged and solid state fermentations. Laccase and cellulase production by these organisms were tested in submerged and solid state fermentation. Higher levels of laccase and cellulase activity were seen in solid state fermentation than in submerged fermentation. Enzymes such as cellulase were detected both in solid and submerged fermentation. The results clearly explain that Laccaria fraterna and Pleurotus ostreatus are potential candidates for the production of industrially important enzymes using cheap raw materials such as agro-wastes.

© 2007 IUP . All Rights Reserved.

Environment-Wide Reprogramming of mRNAs Encoding Phosphate Translocator and Glucosyltransferase in Relation to Cellulosic Biomass Accumulation in Peanut

-- Godson O Osuji and Tassine Brown

Glucosyltransferase and phosphate (Pi) translocator are key enzymes in glucan biosynthesis. The reprogramming of the mRNAs encoding glucosyltransferase and Pi translocator by environment-wide factors that induce the isomerization of Glutamate Dehydrogenase (GDH) was studied by northern analysis. Equal concentrations of total RNA from environment-wide treated peanuts were probed with those GDH-synthesized RNAs that were homologous to the mRNAs encoding glucosyltransferase and Pi translocator. Those environment-wide factors (CTP, 4NTPs) up-regulated the mRNA encoding Pi translocator by about eight-fold and down-regulated the mRNA encoding glucosyltransferase by at least five-fold. Conversely, those factors (3NTPs, GTP) up-regulated the mRNA encoding glucosyltransferase by about seven-fold and down-regulated the mRNA encoding Pi translocator by at least five-fold. The level of the mRNA encoding glucosyltransferase was directly related to the accumulated cellulosic biomass. But a threshold level of the mRNA encoding the Pi translocator was necessary in order for cellulosic biomass to begin to accumulate. The reciprocal relationships between the mRNAs encoding Pi translocator and glucosyltransferase, in the light of the isomeric sequence similarities among the GDH-synthesized RNAs, suggested that the mRNAs were reprogrammed by the GDH-synthesized RNAs. These results could be useful in the environmental manipulation of the structure and yield of cellulose.

© 2007 IUP . All Rights Reserved.

In Vitro Rapid Propagation of Aloe vera L., a High Valued Medicinal Plant Through Rhizome and Axillary Bud Proliferation

-- Binita B Chaplot,
Ashok M Dave and Yogesh T Jasrai

Protocols for plant propagation through rhizome and axillary bud were established for Musabar—Aloe vera L. (Liliaceae). Murashige and Skoog's (MS) medium with 4.4 µM benzyladenine (BA) with 2.88 µM Indole-acetic acid (IAA) and 0.98 µM Indole-3-butyric acid (IBA) elicited the maximum number of shoots (35 multiple shoots) on rhizome explants and (12 shoots) from axillary node explants. The regenerated shoots were rooted on half MS medium with 1.14 µM IAA within 12 days. Almost, 97% of the rooted shoots survived hardening when transferred to the field. The regenerated plants did not show any morphological change and variation in levels of secondary metabolite when compared with the mother stock.

© 2007 IUP . All Rights Reserved.

Evaluation of Parameters for Genetic Transformation Studies in Nicotiana tobaccum

-- Chakravarthy R and Sadanandam A

The paper discusses the applications of genetic engineering protocols for efficient synthesis of high yielding varieties in tobacco species. Transgenic Nicotiana species can be synthesized using Agrobacterium tumefaciens as a vector that causes manipulation in the fundamental biological processes. Successful experimental protocol on genetic transformation is proposed to develop healthy transgenic gene expression in Nicotiana tobaccum.

© 2007 IUP . All Rights Reserved.

In Vitro Regeneration and Slow Growth Studies on Rauvolfia serpentina

-- P E Rajasekharan,
S R Ambika and S Ganeshan

Rauvolfia Serpentina (Linn.) Benth. ex Kurz plants were collected from Western Ghats and established as ex situ collection in Bangalore under glass house and field conditions. From the above source plantlets were successfully regenerated from shoot cultures of Rauvolfia serpentina initiated from auxiliary meristems. MS medium containing 4.44 µM BA and 0.54 µM NAA resulted in best shoot proliferation. Low temperature storage of vitroplants appeared highly promising and plantlets were normal and healthy even after one year. Shoot tips and single nodal cuttings were used for in vitro multiplication. Excised shoots were rooted on half-strength MS supplemented with 1.0 mg/litre each of IBA and IAA. Within 3 weeks rooting was 100%. After acclimatization 95% of the plantlets survived.

© 2007 IUP . All Rights Reserved.

A Survey on Antisense Oligonucleotides Efficacy Prediction

-- Divya Mohan

Developments in the sequencing of human genome have led to the use of short fragments of nucleic acid, commonly known as oligonucleotides as curative agents. Over the past three decades, antisense oligonucleotide technology has emerged as a valid approach to selectively modulate gene expression. However, in practice, only a few complementary oligonucleotides, show effective suppression. The reasons and the various forms of experiments have been dealt with in the work. The primary goal of this survey is to emphasize the different techniques used for antisense oligonucleotide efficacy prediction.

© 2007 IUP . All Rights Reserved.