Decoding the wheat awn transcriptome and overexpressing TaRca1β in rice for heat stress tolerance

Plant Molecular Biology - Role of Rubisco Activase in imparting thermotolerance to the photosynthetic apparatus under high temperature. Thus, to improve the grain filling, we need to fine tune...     

Origin and diversification of Indian Ceropegieae (Apocynaceae) and its possible relation to the Indian monsoon

The Indian subcontinent has experienced a major shift in climatic regime from a wet tropical regime to increased seasonal rainfall, since the late Miocene. This shift has been attributed to the intensification of monsoons, which led to opening up of dry habitats in humid forests and formation of deciduous forests. We explored the role of this climatic shift in the origin and diversification of dry‐adapted plant genera Ceropegia and Brachystelma (Ceropegiae, Asclepiadoideae, Apocynaceae). We sampled Ceropegia and Brachystelma from across India and used five markers (two nuclear and three plastid regions) to reconstruct a global phylogeny of this group. Indian members of the tribe Ceropegiae were derived from Africa through at least four independent dispersal events. All dispersal events occurred in late Miocene after establishment of a monsoon climate. One of these early dispersing lineages underwent rapid radiation in peninsular India, giving rise to around 50 species. Thus, both dispersal and diversification events coincided with the intensification of monsoons and concomitant aridification. The role of environment in the evolution of floral characteristics and root type in the Indian radiation is also discussed. This is one of the first reports on a dry‐adapted endemic radiation of plants in India.     

MAPK signaling regulates c‐MYC for melanoma cell adaptation to asparagine restriction

Amino acid restriction is among promising potential cancer treatment strategies. However, cancer cells employ a multitude of mechanisms to mount resistance to amino acid restriction, which impede the latter’s clinical development. Here we show that MAPK signaling activation in asparagine‐restricted melanoma cells impairs GSK3‐β‐mediated c‐MYC degradation. In turn, elevated c‐MYC supports ATF4 translational induction by enhancing the expression of the amino acid transporter SLC7A5, increasing the uptake of essential amino acids, and the subsequent maintenance of mTORC1 activity in asparagine‐restricted melanoma cells. Blocking the MAPK‐c‐MYC‐SLC7A5 signaling axis cooperates with asparagine restriction to effectively suppress melanoma cell proliferation. This work reveals a previously unknown axis of cancer cell adaptation to asparagine restriction and informs mechanisms that may be targeted for enhanced therapeutic efficacy of asparagine limiting strategies.     

The Oxytricha trifallax Macronuclear Genome: A Complex Eukaryotic Genome with 16,000 Tiny Chromosomes

The macronuclear genome of the ciliate Oxytricha trifallax displays an extreme and unique eukaryotic genome architecture with extensive genomic variation. During sexual genome development, the expressed, somatic macronuclear genome is whittled down to the genic portion of a small fraction (∼5%) of its precursor “silent” germline micronuclear genome by a process of “unscrambling” and fragmentation. The tiny macronuclear “nanochromosomes” typically encode single, protein-coding genes (a small portion, 10%, encode 2–8 genes), have minimal noncoding regions, and are differentially amplified to an average of ∼2,000 copies. We report the high-quality genome assembly of ∼16,000 complete nanochromosomes (∼50 Mb haploid genome size) that vary from 469 bp to 66 kb long (mean ∼3.2 kb) and encode ∼18,500 genes. Alternative DNA fragmentation processes ∼10% of the nanochromosomes into multiple isoforms that usually encode complete genes. Nucleotide diversity in the macronucleus is very high (SNP heterozygosity is ∼4.0%), suggesting that Oxytricha trifallax may have one of the largest known effective population sizes of eukaryotes. Comparison to other ciliates with nonscrambled genomes and long macronuclear chromosomes (on the order of 100 kb) suggests several candidate proteins that could be involved in genome rearrangement, including domesticated MULE and IS1595-like DDE transposases. The assembly of the highly fragmented Oxytricha macronuclear genome is the first completed genome with such an unusual architecture. This genome sequence provides tantalizing glimpses into novel molecular biology and evolution. For example, Oxytricha maintains tens of millions of telomeres per cell and has also evolved an intriguing expansion of telomere end-binding proteins. In conjunction with the micronuclear genome in progress, the O. trifallax macronuclear genome will provide an invaluable resource for investigating programmed genome rearrangements, complementing studies of rearrangements arising during evolution and disease.     

Novel method to differentiate 3T3 L1 cells in vitro to produce highly sensitive adipocytes for a GLUT4 mediated glucose uptake using fluorescent glucose analog

Adipocytes play a vital role in glucose metabolism. 3T3 L1 pre adipocytes after differentiation to adipocytes serve as excellent in vitro models and are useful tools in understanding the glucose metabolism. The traditional approaches adopted in pre adipocyte differentiation are lengthy exercises involving the usage of IBMX and Dexamethasone. Any effort to shorten the time of differentiation and quality expression of functional differentiation in 3T3 L1 cells in terms of enhanced Insulin sensitivity has an advantage in the drug discovery process. Thus, there is a need to develop a new effective method of differentiating the pre adipocytes to adipocytes and to use such methods for developing efficacious therapeutic molecules. We observed that a combination of Dexamethasone and Troglitazone generated differentiated adipocytes over fewer days as compared to the combination of IBMX and Dexamethasone which constitutes the standard protocol followed in our laboratory. The experiments conducted to compare the quality of differentiation yielded by various differentiating agents indicated that the lipid droplet accumulation increased by 112 % and the GLUT4 mediated glucose uptake by 137 % in cells differentiated with Troglitazone and Dexamethasone than in cells differentiated traditionally. The comparative studies conducted for evaluating efficient measurable glucose uptake by GOPOD assay, radioactive ³H-2-deoxy-D-glucose assay and by non-radioactive 6-NBDG (fluorescent analog of glucose) indicated that the non-radioactive method using 6-NBDG showed a higher signal to noise ratio than the conventional indirect glucose uptake method (GOPOD assay) and the radioactive ³H-2-deoxy-D-glucose uptake method. Differentiated 3T3 L1 cells when triggered with 2.5 ng/mL of Insulin showed 3.3 fold more glucose uptake in non-radioactive method over the radioactive ³H-2-deoxy-D-glucose uptake method. The results of this study have suggested that a combination of Dexamethasone and Troglitazone for 3T3 L1 cell differentiation helps in better quality differentiation over a short period of time with increased sensitivity to Insulin. The application of these findings for developing new methods of screening novel Insulin mimetics and for evaluating the immunological responses has been discussed.     

Comparative analysis of chromosome 2A molecular organization in diploid and hexaploid wheat

Molecular Biology Reports - Diploid A genome wheat species harbor immense genetic variability which has been targeted and proven useful in wheat improvement. Development and deployment of...     

A 286 bp upstream regulatory region of a rice anther-specific gene, OSIPP3, confers pollen-specific expression in Arabidopsis

OSIPP3 gene (coding for pectin methylesterase inhibitor protein) was isolated from a pre-pollinated inflorescence-specific cDNA library by differential screening of stage-specific libraries from Oryza sativa. OSIPP3 is present in the genome of rice as a single copy gene. OSIPP3 gene was expressed exclusively in the pre-pollinated spikelets of rice. Upstream regulatory region (URR) of OSIPP3 was isolated and a series of 5′-deletions were cloned upstream of GUS reporter gene and were used to transform Arabidopsis. OSIPP3_del1 and del2 transgenic plants showed GUS expression in root, anther and silique, while OSIPP3_del3 showed GUS activity only in anthers and siliques. Pollen-specific expression was observed in case of plants harboring OSIPP3_del4 construct. It can, therefore, be concluded that the OSIPP3 URR between ?178 and +108 bp is necessary for conferring pollen-specific expression in Arabidopsis.