Age-dependent changes in rat liver microsomal and mitochondrial NADPH-dependent lipid peroxidation.

Purified outer membrane proteins O-8 and O-9 were able to bind to the peptidoglycan sacculi in sodium dodecyl sulfate solution. Binding was stimulated by lipopolysaccharide, that of protein O-9 being stimulated more remarkably. Proteins which had been heated in sodium dodecyl sulfate solution did not bind to the peptidoglycan sacculi even in the presence of lipopolysaccharide, while heated lipopolysaccharide stimulated the binding of non-heated proteins. The removal by pronase of the lipoprotein covalently bound to the peptidoglycan sacculi did not change the protein binding ability of the sacculi.     

Examination of Duct Physiology in the Human Mammary Gland

BackgroundThe human breast comprise several ductal systems, or lobes, which contain a small amount of fluid containing cells, hormones, proteins and metabolites. The complex physiology of these ducts is likely a contributing factor to the development of breast cancer, especially given that the vast majority of breast cancers begin in a single lobular unit.MethodsWe examined the levels of total protein, progesterone, estradiol, estrone sulfate, dehydroepiandrosterone sulfate, and macrophages in ductal fluid samples obtained from 3 ducts each in 78 women, sampled twice over a 6 month period. Samples were processed for both cytological and molecular analysis. Intraclass correlation coefficients and mixed models were utilized to identify significant data.ResultsWe found that the levels of these ductal fluid components were generally uncorrelated among ducts within a single breast and over time, suggesting that each lobe within the breast has a distinct physiology. However, we also found that estradiol was more correlated in women who were nulliparous or produced nipple aspirate fluid.ConclusionsOur results provide evidence that the microenvironment of any given lobular unit is unique to that individual unit, findings that may provide clues about the initiation and development of ductal carcinomas.     

Environmental forcing of nitrogen fixation in the eastern tropical and sub-tropical North Atlantic Ocean

During the winter of 2006 we measured nifH gene abundances, dinitrogen (N(2)) fixation rates and carbon fixation rates in the eastern tropical and sub-tropical North Atlantic Ocean. The dominant diazotrophic phylotypes were filamentous cyanobacteria, which may include Trichodesmium and Katagnymene, with up to 10(6) L(-1)nifH gene copies, unicellular group A cyanobacteria with up to 10(5) L(-1)nifH gene copies and gamma A proteobacteria with up to 10(4) L(-1)nifH gene copies. N(2) fixation rates were low and ranged between 0.032-1.28 nmol N L(-1) d(-1) with a mean of 0.30 ± 0.29 nmol N L(-1) d(-1) (1σ, n = 65). CO(2)-fixation rates, representing primary production, appeared to be nitrogen limited as suggested by low dissolved inorganic nitrogen to phosphate ratios (DIN:DIP) of about 2 ± 3.2 in surface waters. Nevertheless, N(2) fixation rates contributed only 0.55 ± 0.87% (range 0.03-5.24%) of the N required for primary production. Boosted regression trees analysis (BRT) showed that the distribution of the gamma A proteobacteria and filamentous cyanobacteria nifH genes was mainly predicted by the distribution of Prochlorococcus, Synechococcus, picoeukaryotes and heterotrophic bacteria. In addition, BRT indicated that multiple a-biotic environmental variables including nutrients DIN, dissolved organic nitrogen (DON) and DIP, trace metals like dissolved aluminum (DAl), as a proxy of dust inputs, dissolved iron (DFe) and Fe-binding ligands as well as oxygen and temperature influenced N(2) fixation rates and the distribution of the dominant diazotrophic phylotypes. Our results suggest that lower predicted oxygen concentrations and higher temperatures due to climate warming may increase N(2) fixation rates. However, the balance between a decreased supply of DIP and DFe from deep waters as a result of more pronounced stratification and an enhanced supply of these nutrients with a predicted increase in deposition of Saharan dust may ultimately determine the consequences of climate warming for N(2) fixation in the North Atlantic.     

Exotic shrub invasion in an undisturbed wetland has little community-level effect over a 15-year period

In this long-term study, we examined the invasion by the exotic shrub glossy buckthorn (Rhamnus frangula L.) and the response of co-occurring plants in a large, undisturbed wetland. We first sampled the vegetation in 1991 and repeated the sample 15 years later using the same, permanently located sample units (n = 165). Despite dramatic increases in the abundance of buckthorn, the invasion elicited little apparent response by the resident plant community. Species richness and cover in the herbaceous plant stratum had no apparent relationship with change in buckthorn cover. The number of shrub species other than buckthorn showed no relationship with change in buckthorn cover, but the cover of other shrubs decreased as buckthorn cover increased. Species composition changed independently of changes in buckthorn cover. These results show that dramatic increases in the abundance of an invasive species do not necessarily cause large changes in the native plant community and suggest disturbance history influences community response to invasion.     

Can axes conventions of the trunk reference frame influence breast displacement calculation during running?

To obtain breast motion relative to the trunk, skin markers are used to define a local coordinate system (trunk), with respect to the global reference frame. This study aimed to quantify any differences in multiplanar breast displacement relative to the trunk using the first axis of rotation as either the mediolateral or longitudinal axis. Ten female participants ran on a treadmill (10 kph) in three different breast supports (no bra, everyday bra, sports bra). Four reflective markers placed on the trunk and right nipple were tracked using eight infrared cameras (200 Hz) during five running gait cycles in each breast support condition. Following marker identification, right breast multiplanar displacements were calculated relative to the trunk using either the mediolateral axis or the longitudinal axis as the first rotational axis to define the orthogonal local coordinate system. Results showed that there was a significant difference (8.2%) in superioinferior breast displacement in the sports bra condition when calculated using different axes conventions for the trunk segment. Furthermore, the greatest magnitude of breast displacement occurred in a different direction depending upon the selection of the first rotational axis. The definition of the primary reference axis of the trunk significantly alters the magnitude of superioinferior breast displacement and therefore it is recommended that the previously reported ‘stable’ longitudinal axis should be defined as the first rotational axis during running. Caution should also be used as the axes convention influences the magnitude and direction of breast support requirements, which has important implications for bra design.     

Regulation of follicular development by diethylstilboestrol in ovaries of immature rats

Immature female rats received either one injection of 2 mg diethylstilboestrol (DES)/rat subcutaneously and were killed 12 h later or received two injections of DES at 0 and 24 h and were killed at 24, 36 and 48 h after the initial injection. The ovarian follicles were released by enzymic digestion with collagenase and separated into those of small, medium and large diameter (less than 200 microns, 200-400 microns and greater than 400 microns) by filtration through graded Teflon sieves and granulosa cells were extracted from these follicles. The ovaries of immature rats treated with pregnant mares' serum gonadotrophin (PMSG) were used for comparative purposes. Incorporation of [3H]thymidine into granulosa cell DNA was augmented by DES and by PMSG. Small follicles were more strongly stimulated by DES at 12 h than those of other sizes, but rates increased significantly in medium and large follicles at 48 h. Aromatase activity in the DES-treated group was low at all times and in all follicles. Rates of oestrogen and progesterone production in response to 36 h of exposure to follicle-stimulating hormone (FSH) in vitro were significantly lower than in the PMSG-treated group. FSH-stimulated steroid production in the DES group at 36-48 h was lower, particularly in the medium follicles. A significant rise in serum FSH, luteinizing hormone (LH) and progesterone concentrations was noted only at 36 h after DES treatment, while serum and follicular fluid oestrogen values remained unchanged. When these changes were compared with those in PMSG-treated rats, there were obvious differences. The pattern of thymidine incorporation and aromatase activity differed with time and follicle size. Serum FSH and LH values were not affected by PMSG treatment, but serum and follicular fluid oestradiol values increased with time. The PMSG-treated animals ovulated in response to human chorionic gonadotrophin, but the DES-treated rats did not ovulate in spite of the presence of some large antral follicles in the ovaries. These findings show that initial exposure of follicles to high concentrations of oestrogen results in follicles which fail to respond to subsequent gonadotrophin surges and are thereby restricted in their ability to differentiate fully.     

tRNA gene identity affects nuclear positioning

The three-dimensional organization of genomes is dynamic and plays a critical role in the regulation of cellular development and phenotypes. Here we use proximity-based ligation methods (i.e. chromosome conformation capture [3C] and circularized chromosome confrmation capture [4C]) to explore the spatial organization of tRNA genes and their locus-specific interactions with the ribosomal DNA. Directed replacement of one lysine and two leucine tRNA loci shows that tRNA spatial organization depends on both tRNA coding sequence identity and the surrounding chromosomal loci. These observations support a model whereby the three-dimensional, spatial organization of tRNA loci within the nucleus utilizes tRNA gene-specific signals to affect local interactions, though broader organization of chromosomal regions are determined by factors outside the tRNA genes themselves.     

Capturing clapper rails using thermal imaging technology

Capturing sufficient numbers of marsh birds for telemetry studies is difficult due to the secretive nature and inaccessible habitat of the birds. We experimented with thermal imaging technology to locate clapper rails and subsequently capture them from an airboat in South Carolina tidal marshes. This method produced a capture rate of up to 19.2 rails/hr, which exceeded other capture rates in the literature. We believe this technique will improve capture efficiency for clapper rails, and potentially other secretive marsh birds, enhancing opportunities for studying these important species. © 2011 The Wildlife Society.