Search

A major goal of phytoremediation is to transform fast-growing plants with genes from plant species that hyperaccumulate toxic trace elements. We overexpressed the gene encoding selenocysteine methyltransferase (SMT) from the selenium (Se) hyperaccumulator Astragalus bisulcatus in Arabidopsis and Indian mustard (Brassica juncea). SMT detoxifies selenocysteine by methylating it to methylselenocysteine, a nonprotein amino acid, thereby diminishing the toxic misincorporation of Se into protein. Our Indian mustard transgenic plants accumulated more Se in the form of methylselenocysteine than the wild type. SMT transgenic seedlings tolerated Se, particularly selenite, significantly better than the wild type, producing 3- to 7-fold greater biomass and 3-fold longer root lengths. Moreover, SMT plants had significantly increased Se accumulation and volatilization. This is the first study, to our knowledge, in which a fast-growing plant was genetically engineered to overexpress a gene from a hyperaccumulator in order to increase phytoremediation potential.

Signatures of a superlattice structure composed of a quasi periodic arrangement of atomic gold clusters below an epitaxied graphene (EG) layer are examined using dispersive Raman spectroscopy. The gold-graphene system exhibits a laser excitation energy dependant red shift of the 2D mode as compared to pristine epitaxial graphene. The phonon dispersions in both the systems are mapped using the experimentally observed Raman signatures and a third-nearest neighbour tight binding electronic band structure model. Our results reveal that the observed excitation dependent Raman red shift in gold EG primarily arise from the modifications of the phonon dispersion in gold-graphene and shows that the extent of decoupling of graphene from the underlying SiC substrate can be monitored from the dispersive nature of the Raman 2D modes. The intercalated gold atoms restore the phonon band structure of epitaxial graphene towards free standing graphene. [ABSTRACT FROM AUTHOR]

The design and simulation of a GaAs-based quantum cascade laser (QCL) emitting at 6.7 [micro]m is described. Monte Carlo simulation has shown that the proposed QCL has achieved room-temperature lasing at a threshold-current density of 14 kA/[cm.sup.2].

Mucin glycoproteins are major constituents of the glycocalyx that covers mucosal epithelium. Two broad classes of mucins exist: membrane-associated and secretory. Of the secreted mucins, those with cysteine-rich regions are thought to polymerize through disulphide bonds. Among these gel-forming mucins are MUC2, MUC5AC, MUC5B and possibly MUC6. MUC7 lacks cysteine-rich domains and is thought to be secreted as a soluble monomer. Incomplete sequence information prevents classification of other mucins. Tandem repeats of amino acids rich in serine, threonine and proline are a common element in mucin core proteins, giving rise to relatively rigid, linear molecules with great potential for glycosylation. Ten distinct mucin genes have been identified in humans so far. Patterns of expression vary greatly. While MUC9, or oviductin, appears to be restricted to oviduct, the transmembrane mucin MUC1 is widely expressed. Proven functions for the different mucins are largely unknown, although potential functions are addressed in this review. Genetic and protein sequence information and expression profiles are also summarized, followed by a description of mucin assembly. Special attention is given to mucin expression in male and female reproductive tracts. [ABSTRACT FROM AUTHOR]

Reproductive tract epithelia are characterized by the presence of a thick, apical glycocalyx. This glycoprotein coat is drastically reduced in the uterus of many species during the time of embryo implantation. Recent studies indicate that mucin glycoproteins constitute a large proportion of the apical glycocalyx. One of these mucins, Muc-1, has particularly important functions at the luminal surface of the uterus and other female reproductive tract tissues. Muc-1 appears to play a dominant role in maintaining a functionally non-receptive uterine surface with regard to blastocyst attachment. Conversion to a receptive uterine state is brought about by the concerted actions of ovarian steroid hormones that in several species also strongly modulate Muc-1 protein and mRNA expression. Muc-1 also appears to serve a general function in protecting reproductive tract mucosa since Muc-1 null mice are particularly prone to bacterial infection. Collectively, these studies indicate that mucins, including Muc-1, play important barrier roles in reproductive processes and protection from bacterial pathogenesis in the female reproductive tract. [ABSTRACT FROM AUTHOR]

Background: A malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma, characterized by an aggressive course and forms a diagnostic challenge, in view of its varied histomorphology. The present study is a comprehensive analysis, including histopathological spectrum of 63 MPNSTs that forms a substantial study from an Indian perspective. Materials and Methods: Clinicopathological features of 63 MPNSTs, diagnosed during a period from January 2002 to December 2006, at a tertiary cancer referral center in Mumbai, India, were analyzed. Statistical analysis was carried out using SPSS (version 14) and STRATA. Difference in events was noted in 50 cases with selected variables. Disease free survival (DFS) was calculated by Kaplan-Meir analysis at the end of 1 year. Results: More cases were identified in > 30 years age (36 cases, 57.14%) group; in men (46 cases, 73%), and were deep-seated (38, 60.3%). Ten cases (15.9%) showed stigmata of multiple neurofibromatosis type 1. Average tumor (T) size was 9.9 cm, with 72.9% cases having T size > 5 cm. More cases were of high grade (56, 88.8%) and high stage (22, 34.9%). Histopathologically, most cases showed hypo- and hypercellular areas (marbleized appearance) of doubly indented spindle cells. Two cases showed epithelioid differentiation. Heterologous elements in the form of osteoid, chondroid, pigmented neuroectodermal (1 case), glandular (1 case) and rhabdomyoblastic differentiation (1 case) were identified in 14 cases (22.2%). S-100 protein positivity was noted in 38/54 cases (70.3%). Maximum cases (45, 71.4%) underwent surgery, including wide excisions and amputations (R0) in 20 cases, marginal excisions (R1) in 4, and intracapsular excision (R2) in 1 case. Nineteen cases underwent adjuvant treatment. A total of 29 cases (46%) showed recurrences and 22 (34.9%) showed multifocality and/or metastasis. Four patients succumbed to the disease in 1 year. The DFS was 53.1%. Cases ≤30 years of age (P- value = 0.007), T size > 5 cm, and with high grade (P = 0.18) and stage (P = 0.00) showed more recurrences, metastasis, and death. Conclusions: A MPNST has multifaceted histomorphology. Its objective identification necessitates the incorporation of clinicopathological features and IHC with S-100 protein. Younger age, high grade and stage, and increased T size significantly relate to aggressive disease. Wide excision forms the optimal treatment with options of adjuvant CT/RT in individual cases.