Identification of an endocrine disrupting agent from corn with mitogenic activity

A mitogenic agent in corncob bedding and fresh corn products disrupts sexual behavior and estrous cyclicity in rats. The mitogenic activity resides in an isomeric mixture of linoleic acid derivatives with a tetrahydrofuran ring and two hydroxyl groups (THF-diols) that include 9, (12)-oxy-10,13-dihydroxystearic acid and 10, (13)-oxy-9,12-dihydroxystearic acid. Synthetic THF-diols stimulated breast cancer cell proliferation in vitro and disrupted the estrous cycle in female rats at oral doses of approximately 0.30 mg/kg body weight/day. Exposure to THF-diols may disrupt endocrine function in experimental animals at doses approximately 200 times lower than classical phytoestrogens, promote proliferation of breast or prostate cancer, and adversely affect human health.     

Role of N-cadherin in bone formation

Cell-cell adhesion mediated by cadherins is essential for the function of bone forming cells during osteogenesis. Here, the evidence that N-cadherin is an important regulator of osteoblast differentiation and osteogenesis is reviewed. Osteoblasts express a limited number of cadherins, including the classic N-cadherin. The expression profile of N-cadherin in osteoblasts during bone formation in vivo and in vitro suggests a role of this molecule in osteogenesis. Functional studies using neutralizing antibodies or antisense oligonucleotides indicate that N-cadherin is involved in the control the expression of osteoblast marker gene expression and differentiation. Cleavage of N-cadherin during osteoblast apoptosis also suggests a role of N-cadherin-mediated-cell-cell adhesion in osteoblast survival. Hormonal and local factors that regulate osteoblast function also regulate N-cadherin expression and subsequent cell-cell adhesion associated with osteoblast differentiation or survival. Signaling mechanisms involved in N-cadherin-mediated cell-cell adhesion and osteoblast gene expression have also been identified. Alterations of N-cadherin expression are associated with abnormal osteoblast differentiation and osteogenesis in pathological conditions. These findings indicate that N-cadherin plays a role in normal and pathological bone formation and provide some insight into the process involved in N-cadherin-mediated cell-cell adhesion and differentiation in osteoblasts.     

Coupled tRNA(Sec)-dependent assembly of the selenocysteine decoding apparatus

SECIS elements recode UGA codons from "stop" to "sense." These RNA secondary structures, present in eukaryotic selenoprotein mRNA 3' untranslated regions, recruit a SECIS binding protein, which recruits a selenocysteine-specific elongation factor-tRNA complex. Elucidation of the assembly of this multicomponent complex is crucial to understanding the mechanism of selenocysteine incorporation. Coprecipitation studies identified the C-terminal 64 amino acids of the elongation factor as sufficient for interaction with the SECIS binding protein. Selenocysteyl-tRNA is required for this interaction; the two factors do not coprecipitate in its absence. Finally, through promoting this interaction, selenocysteyl-tRNA stabilizes the C-terminal domain of the elongation factor. We suggest that the coupling effect is critical to preventing nonproductive decoding attempts and hence forms a basis for effective selenoprotein synthesis.     

Transgenic Plant Monitor (TPM): a relational database for the management and analysis of information in plant tissue culture and transformation laboratories

Increased public concern and strict statutory regulations relating tothe generation and exploitation of genetically modified organisms, make itimperative to track accurately individual plants through DNA transformationprogrammes. The ability to rapidly retrieve information associated withspecifictransgenic events and to provide accurate reports on demand is an increasinglyimportant feature for public research laboratories. Transgenic Plant Monitor(TPM) has been developed as a database structured to allow efficient recording,monitoring and analysis of the extensive and complex data generated in planttissue culture and transformation experiments. TPM is built upon the widelyavailable Microsoft Access database engine and can be readily adoptedand/or adapted by other users. The key features and the utility of TPM as aresearch tool are discussed in this article.     

Temporal dynamics of three culturable γ-Proteobacteria taxa in salt marsh sediments

Temporal dynamics of three marine -Proteobacteria taxa withculturable members were followed in sediment communities in southeastern USsaltmarshes using a whole-genome hybridization approach. Labeled DNA from threebacterial isolates was used to probe sediment community DNA from two saltmarshes on Sapelo Island, GA at multiple time points over a three-year period.The relative abundance of the three isolates (and their close relatives)accounted for up to 28% of the total sediment community DNA. Hybridizationsignals for the taxon represented by isolate SIGA28M (with a 16S rRNA sequencesimilarity of 97% to Vibrio proteolyticus) showedsignificant temporal variation in both marshes, varying from 1% to 28% over thethree-year period. The taxa represented by isolates SIGA172a and SIGA198 (16SrRNA sequence similarities of 90% and 92% to Shewanellafrigidimarina and Vibrio nigripulchritudo,respectively) accounted for less than 6% of the sediment community at any timepoint. The variation in relative abundance of these three groups did not appearto follow clear seasonal trends, and could not be readily correlated withenvironmental variables.