Registros de fitoclastos mesozoicos nas formações Sriperumbudur (Bacia de Palar), Kota (Sub-bacia de Chintalapudi) e Dubrajpur (Bacia de Rajmahal), Índia

Os estudos de cutículas de plantas fósseis em amostras de três poços perfurados na Índia localizados nos estados de Andhra Pradesh (Formação Kota/Gangapur, Sub-bacia de Chintalapudi, Graben Godavari, Jurássico–Cretáceo), Tamil Nadu (Formação Sriperumbudur, Bacia Palar, Jurássico Superior–Cretáceo Inferior) e Jharkhand (Formação Dubrajpur, Bacia de Rajmahal, Jurássico Superior e Cretáceo Inferior) são apresentados aqui. Cutículas e palinomorfos foram recuperados pelo método‑padrão de preparação palinológica no laboratório de Palinologia do Gondwana do Birbal Sahni Institute of Palaeosciences, Lucknow, Índia. Espécimes fósseis foram examinados com microscópio óptico binocular, e fotomicrografias foram obtidas com câmera digital. Vinte e sete morfotipos de cutículas fósseis (ocasionalmente representando estômatos, tricomas e estruturas secretoras) e outros tecidos (ex.: parênquima plicado) foram recuperados. A análise morfológica das cutículas e dos palinomorfos associados refletem a presença de diferentes grupos de plantas (Bennettitales, Coniferales, Ginkgoales, Polypodiales e Pteridospermales). As cutículas exibem distintas estruturas (ex.: estômatos ciclocíticos e estruturas secretoras) que permitem comparações com plantas atuais e fósseis. Conclui-se que o estudo das cutículas fósseis bem preservadas e dos palinomorfos associados permitem inferências taxonômicas na composição das floras-mãe.The studies of fossil plant cuticles in palynological samples recovered from three cored boreholes located in the Indian states of Andhra Pradesh (Kota/Gangapur Formation, Chintalapudi Sub-basin, Godavari Graben, Jurassic–Cretaceous), Tamil Nadu (Sriperumbudur Formation, Palar Basin, Upper Jurassic–lowermost Cretaceous), and Jharkhand (Dubrajpur Formation, Rajmahal Basin, Upper Jurassic–Lower Cretaceous) are presented herein. Cuticles and palynomorphs were recovered by standard palynological practices in the Gondwana Palynological Laboratory of the Birbal Sahni Institute of Palaeosciences, Lucknow, India. Fossil specimens were examined under a binocular microscope and photomicrographs were taken with a digital camera. Twenty seven morphotypes of fossil cuticles (occasionally representing stomata, trichomes and secretory structures) and other tissues (e.g., a plicate parenchyma) were recovered. The morphological analysis of cuticles and associated palynomorphs reflect the presence of different groups of plants (Bennettitales, Coniferales, Ginkgoales, Polypodiales, and Pteridospermales). In some occasions, cuticles display distinct structures (e.g., monocyclic stomata, secretory structures) that allow comparisons with some extant and fossil genera. We conclude that the study of well-preserved fossil cuticles and associated palynomorphs allow taxonomic inferences on the composition of the parent floras

Karakoram: An Integral Part of Perigondwana ProvinceFossiliferous Evidences

86-91The sedimentary sequence from the Chongtash Formation, Karakoram area (Upper Shyok Valley) has yielded Lower Gondwana palynomorphs referable to Early Permian age. Though these palynomorphs are not well preserved but can be identified at generic level. The palynoassemblage shows dominance of monosaccates viz. Parasaccites, Plicatipollenites, Divarisaccus, and Caheniasaccites. Few striate disaccates viz. Striatopodocarpites, Faunipollenites, Striatites and non-striate disaccates viz. Scheuring ipollenites and Ibisporites have also been recorded. Among trlietes presence of Callumispora and <i style="mso-bidi-font-style: normal">Indotriradites have been observed. Except <i style="mso-bidi-font-style: normal">Cordaitina all taxa undoubtedly belong to Gondwana. The palynocomposition especially dominance of Parasaccites and presence of few striate and non-striate disaccates shows that the assemblage is equivalent to Talchir/ Upper Karharbari Formation (Late Asselian-Sakmarian) of India. This palynoassemblage from Chongtash Formation of Karakoram also shows resemblance with marine Lower Gondwana palynoassemblage of Salt Range (Pakistan). This finding of early Permian palynomorphs from Chongtash Formation of Karakoram area also supports the contention that during early Permian Karakoram was a part of Peri-Gondwanan province and was located on the northern margin of Indian subcontinent

Covalent modification of cysteine 193 impairs ATPase function of nucleotide-binding domain of a Candida drug efflux pump

N-ethylmaleimide (NEM) impairs the ATPase function of N-terminal NBD of Candida drug resistance gene product Cdr1p. To identify the reactive cysteine(s) for such a contribution, we adopted a three-arm approach that included covalent modification, cysteine mutagenesis, and structure homology modeling. The covalent modification results clearly indicate the ability of NEM and iodoacetic acid (IAA) to potently inhibit the ATPase activity of N-terminal NBD. Since this domain contains five cysteine residues in its sequence, we mutated each and found four of these (C325A, C363A, C402A, and C462A) to stay sensitive to NEM/IAA modification and influence ATPase activity, while C193A mutation completely abrogated the catalytic function. The structural homology modeling data further validate these biochemical findings by ruling out any plausible interactions within the cysteine residues, and deriving the importance of Cys-193 in lying at a bond length clearly feasible to interact with ATP and divalent cation to critically influence ATP hydrolysis

Purification and characterization of the N-terminal nucleotide binding domain of an ABC drug transporter of Candida albicans: uncommon cysteine 193 of Walker A is critical for ATP hydrolysis

The Candida drug resistance protein Cdr1p (~170 kDa) is a member of ATP binding cassette (ABC) superfamily of drug transporters, characterized by the presence of 2 nucleotide binding domains (NBD) and 12 transmembrane segments (TMS). NBDs of these transporters are the hub of ATP hydrolysis activity, and their sequence contains a conserved Walker A motif (GxxGxGK&#x0332;S/T). Mutations of the lysine residue within this motif abrogate the ability of NBDs to hydrolyze ATP. Interestingly, the sequence alignments of Cdr1p NBDs with other bacterial and eukaryotic transporters reveal that its N-terminal NBD contains an unusual Walker A sequence (GRPGAGC&#x0332;ST), as the invariant lysine is replaced by a cysteine. In an attempt to understand the significance of this uncommon positioning of cysteine within the Walker A motif, we for the first time have purified and characterized the N-terminal NBD (encompassing first N-terminal 512 amino acids) of Cdr1p as well as its C193A mutant protein. The purified NBD-512 protein could exist as an independent functional general ribonucleoside triphosphatase with strong divalent cation dependence. It exhibited ATPase activity with an apparent Km in the 0.8-1.0 mM range and Vmax in the range of 147-160 nmol min-1 (mg of protein)-1. NBD-512-associated ATPase activity was also sensitive to inhibitors such as vanadate, azide, and NEM. The Mut-NBD-512 protein (C193A) showed a severe impairment in its ability to hydrolyze ATP (95%); however, no significant effect on ATP (TNP-ATP) binding was observed. Our results show that C193 is critical for N-terminal NBD-mediated ATP hydrolysis and represents a unique feature distinguishing the ATP-dependent functionality of the ABC transporters of fungi from those found in bacteria and other eukaryotes

SRE1 and SRE2 are two specific steroid-responsive modules of Candida drug resistance gene 1 (CDR1) promoter

CDR1 gene encoding an ATP-driven drug extrusion pump has been implicated in the development of azole-resistance in Candida albicans. Although the upregulation of CDR1 expression by various environmental factors has been documented, the molecular mechanism underlying such process is poorly understood. We have demonstrated earlier that the CDR1 promoter encompasses a large number of cis-regulatory elements, presumably mediating its response to various drugs. In this study we have identified a novel steroid responsive region (SRR) conferring β-oestradiol and progesterone inducibility on the CDR1 promoter. The SRR is located −696 to −521 bp upstream of the transcription start site; it is modular in nature and can confer steroid responsiveness to a heterologous promoter (ADH1) linked to a GFP reporter gene. In vitro DNase I protection analyses of SRR revealed two progesterone responsive sequences (−628 to −594 and −683 to −648) and one β-oestradiol responsive sequence (−628 to −577), which was further corroborated by the gel mobility shift assay. Deletion analyses within the SRR further delimited these steroid responsive sequences into two distinct elements, viz. SRE1 and SRE2. While SRE1 (−677 to −648) responds only to progesterone, SRE2 (−628 to −598) responded to both progesterone and β-oestradiol. Both SRE1 and SRE2 were specific for steroids, as they did not respond to other drugs, such as cycloheximide, miconazole and terbinafine. In silico comparison of the SRE½ with the promoter sequences of other MDR (CDR2 and PDR5) and non-MDR (HSP90) steroid-responsive genes revealed a similarity with respect to conservation of three 5 bp stretches (AAGAA, CCGAA and ATTGG). Taken together, we have identified a novel steroid responsive cis-regulatory sequence in the CDR1 promoter, which presumably can be instrumental in understanding the steroid response cascade in Candida albicans

Optimizing drug combinations against multiple myeloma using a quadratic phenotypic optimization platform (QPOP).

Multiple myeloma is an incurable hematological malignancy that relies on drug combinations for first and secondary lines of treatment. The inclusion of proteasome inhibitors, such as bortezomib, into these combination regimens has improved median survival. Resistance to bortezomib, however, is a common occurrence that ultimately contributes to treatment failure, and there remains a need to identify improved drug combinations. We developed the quadratic phenotypic optimization platform (QPOP) to optimize treatment combinations selected from a candidate pool of 114 approved drugs. QPOP uses quadratic surfaces to model the biological effects of drug combinations to identify effective drug combinations without reference to molecular mechanisms or predetermined drug synergy data. Applying QPOP to bortezomib-resistant multiple myeloma cell lines determined the drug combinations that collectively optimized treatment efficacy. We found that these combinations acted by reversing the DNA methylation and tumor suppressor silencing that often occur after acquired bortezomib resistance in multiple myeloma. Successive application of QPOP on a xenograft mouse model further optimized the dosages of each drug within a given combination while minimizing overall toxicity in vivo, and application of QPOP to ex vivo multiple myeloma patient samples optimized drug combinations in patient-specific contexts