Mitochondrial DNA variation in the caramote prawn <Emphasis Type="Italic">Penaeus (Melicertus) kerathurus</Emphasis> across a transition zone in the Mediterranean Sea

In this study we analysed mitochondrial DNA variation in Penaeus kerathurus prawns collected from seven locations along a transect across the Siculo–Tunisian region in order to verify if any population structuring exists over a limited geographical scale and to delineate the putative transition zone with sufficient accuracy. Partial DNA sequences of COI and 16S genes were analysed. In contrast to the highly conservative 16S gene, the COI sequences exhibited sufficient diversity for population analysis. The COI gene revealed low levels of haplotype and nucleotide diversities. The size of the annual landings of this commercial species suggests large population sizes. Hence, the low genetic diversity detected in this study could indicate a possible reduction in effective population sizes in the past. We detected significant genetic differentiation between eastern and western populations likely due to restricted gene flow across the Siculo–Tunisian boundary. We discuss the different evolutionary forces that may have shaped the genetic variation and suggest that the genetic divide is probably maintained by present-day dispersal limitation. R. Zitari-Chatti and N. Chatti are contributed equally to the work.     

Diel variation of phytoplankton functional groups in a subtropical reservoir in southern Brazil during an autumnal stratification period

A knowledge of diel variation and the vertical distribution of phytoplankton communities may contribute to a better understanding of the driving factors of key species. Applying functional-group classification provides important information on the causes of species selection in the pelagic community. The diel variation of phytoplankton functional groups was analysed during an autumnal stratification period with the aim of understanding their changes in the vertical position related to light, mixing regime and grazing pressure. Phytoplankton and zooplankton communities were sampled every 4 h during a 24-h period in a vertical profile in a subtropical meso-eutrophic reservoir. Strong stratification during a 24-h cycle and a mixed clear epilimnion with partial atelomixis marked the autumn season in the Faxinal reservoir, southern Brazil. The highest phytoplankton densities and biomass were found during the second part of the day, a general pattern reported in the literature, and may be explained by zooplankton dynamics. During the 24-h cycle, phytoplankton functional groups lacking a self-regulating capacity and those able to regulate their vertical position were vertically segregated in the lake. The diel behaviour of both groups was driven by the mixing regime (including atelomixis), light and zooplankton grazing pressure.     

Syncyte formation in the microsporangium of <Emphasis Type="Italic">Chrysanthemum</Emphasis> (Asteraceae): a pathway to infraspecific polyploidy

Polyploidy, which is thought to have played an important role in plant evolution and speciation, is prevalent in Chrysanthemum (x = 9). In fact, polyploid series are known in C. zawadskii (2x, 4x, 6x, 8x, and 10x) and C. indicum (2x, 4x, and 6x), but the mechanism by which polyploidization occurs is unknown. Here we show that in diploid individuals of both C. zawadskii and C. indicum, the fusion between two adjacent pollen mother cells (PMCs) occurs at a frequency of 1.1–1.3% early in the first meiotic division. While possessing the chromosomes of both PMCs, the fused cell or syncyte undertakes subsequent meiotic division processes as a single large PMC, producing four 2n pollen grains that are able to germinate. Despite their low frequency, syncyte formation may have played a major role in the production of infraspecific polyploids in Chrysanthemum.     

Evaluation of novel beta-lactam antibiotics in comparison to cefotaxime on plant regeneration of <Emphasis Type="Italic">Citrus sinensis</Emphasis> L. Osb.

Identification of beta-lactam antibiotics that have negligible effects on plant regeneration is a critical step towards the establishment of a reliable Agrobacterium-mediated transformation protocol for perennial trees. In the present report, we have evaluated the effects of the novel beta-lactam antibiotics meropenem and timentin on plant regeneration of a perennial woody fruit plant, Citrus sinensis, in comparison with the commonly used beta-lactam cefotaxime. It was observed that, in contrast to cefotaxime, meropenem and timentin had a positive or no detrimental effect on the shoot regeneration from epicotyl explants. Residual effects of the beta-lactams from shoot regeneration medium also affected the subsequent ability of the roots to elongate. The addition of meropenem and/or timentin in the rooting medium mostly improved or did not affect the rooting ability of the adventitious shoots. These data indicated that meropenem and timentin can positively replace cefotaxime in Agrobacterium-mediated transformation of C. sinensis.     

TEP on the tide in killifish (<Emphasis Type="Italic">Fundulus heteroclitus</Emphasis>): effects of progressively changing salinity and prior acclimation to intermediate or cycling salinity

Transepithelial potentials (TEP) were measured in killifish, acclimated to freshwater (FW), seawater (SW), 33% SW or cycling salinities relevant to tidal cycles in an estuary, and subsequently subjected to salinity changes in progressive or random order. Random compared to progressive salinity changes in an upward or downward direction in FW- and SW-acclimated fish, respectively, did not greatly influence responses to salinity change. Fish acclimated to SW or 33% SW as well as those acclimated to cycling salinities behaved similarly (TEP more positive than +15 mV in 100% SW, decreasing to ~0 mV at 20–40% SW, and more negative than −30 mV in FW). In contrast, FW-acclimated fish displayed a less pronounced TEP response to salinity (0 mV in FW through 20% SW, increasing thereafter to values more positive than +10 mV at 100% SW). We conclude that when evaluated under estuarine tidal conditions, the killifish gill exhibits adaptive electrical characteristics, opposing Na⁺ loss at low salinity and favouring Na⁺ extrusion at high salinity, changes explained at least in part by the Cl⁻ to Na⁺ permeability ratio. Thus animals living in the estuaries can move to lower and higher salinities for short periods with little physiological disturbance, but this ability is lost after acclimation to FW.     

Antifungal and antibacterial activities of indigenous <Emphasis Type="Italic">Streptomyces</Emphasis> isolates from saline farmlands: prescreening,ribotyping and metabolic diversity

A culture collection of 110 indigenous Streptomyces strains originally isolated from saline farmlands (Punjab, Pakistan) using stringent methods was screened biologically and chemically to investigate their potential for the production of bioactive secondary metabolites. In a biological screening the crude extracts obtained from the culture broth of selected strains were analysed for their activity against a set of test organisms, including Gram-positive, Gram-negative bacteria, fungi and microalgae using the disk diffusion bioassay method. Additionally a cytotoxicity test was performed by means of the brine shrimp microwell cytotoxicity assay. In a chemical screening each of the crude extracts was analysed by TLC using various staining reagents and by HPLC-MS/MS measurements. The results depicted an impressive chemical diversity of crude extracts produced by these strains. The taxonomic status of the selected strains was confirmed by preliminary physiological testing and 16S rRNA gene sequencing.     

Elucidation of the effects of lipoperoxidation on the mitochondrial electron transport chain using yeast mitochondria with manipulated fatty acid content

Lipoperoxidative damage to the respiratory chain proteins may account for disruption in mitochondrial electron transport chain (ETC) function and could lead to an augment in the production of reactive oxygen species (ROS). To test this hypothesis, we investigated the effects of lipoperoxidation on ETC function and cytochromes spectra of Saccharomyces cerevisiae mitochondria. We compared the effects of Fe²⁺ treatment on mitochondria isolated from yeast with native (lipoperoxidation-resistant) and modified (lipoperoxidation-sensitive) fatty acid composition. Augmented sensitivity to oxidative stress was observed in the complex III-complex IV segment of the ETC. Lipoperoxidation did not alter the cytochromes content. Under lipoperoxidative conditions, cytochrome c reduction by succinate was almost totally eliminated by superoxide dismutase and stigmatellin. Our results suggest that lipoperoxidation impairs electron transfer mainly at cytochrome b in complex III, which leads to increased resistance to antimycin A and ROS generation due to an electron leak at the level of the Q_O site of complex III.     

Evaluation of antigenotoxicity effects of umbelliprenin on human peripheral lymphocytes exposed to oxidative stress

The protective properties of a prenylated coumarin, umbelliprenin (UMB), on the human lymphocytes DNA lesions were tested. Lymphocytes were isolated from blood samples taken from healthy volunteers. DNA breaks and resistance to H₂O₂-induced damage were measured using a single-cell microgel electrophoresis technique under alkaline conditions (comet assay). Human lymphocytes were incubated in UMB (10, 25, 50, 100, 200, and 400 μM) alone or a combination of different concentrations of UMB (10, 25, 50, 100, 200, and 400 μM) and 25 μM H₂O₂. Untreated cells, ascorbic acid (AA; 25, 50, 100, 200, and 400 μM) and H₂O₂ (25 μM) were considered as negative control, positive control, and the standard antioxidant agent for our study, respectively. Single cells were analyzed with “TriTek Cometscore version 1.5” software. The DNA damage was expressed as percent tail DNA. UMB exhibited a concentration-dependent increase in protection activity against DNA damage induced by 25 μM H₂O₂ (from 67.28% to 39.17%). The antigenotoxic activity of AA, in the range 0–50 μM, was greater than that of UMB. However, no significant difference (p > 0.05) in the protective activity was found between UMB and AA at concentrations of approximately higher than 50 μM.     

Multiple stimulations for muscle–nerve–blood vessel unit in compensatory hypertrophied skeletal muscle of rat surgical ablation model

Tissue inflammation and multiple cellular responses in the compensatory enlarged plantaris (OP Plt) muscle induced by surgical ablation of synergistic muscles (soleus and gastrocnemius) were followed over 10 weeks after surgery. Contralateral surgery was performed in adult Wistar male rats. Cellular responses in muscle fibers, blood vessels and nerve fibers were analyzed by immunohistochemistry and electron microscopy. Severe muscle fiber damage and disappearance of capillaries associated with apparent tissue edema were observed in the peripheral portion of OP Plt muscles during the first week, whereas central portions were relatively preserved. Marked cell activation/proliferation was also mainly observed in peripheral portions. Similarly, activated myogenic cells were seen not only inside but also outside of muscle fibers. The former were likely satellite cells and the latter may be interstitial myogenic cells. One week after surgery, small muscle fibers, small arteries and capillaries and several branched-muscle fibers were evident in the periphery, thus indicating new muscle fiber and blood vessel formation. Proliferating cells were also detected in the nerve bundles in the Schwann cell position. These results indicate that the compensatory stimulated/enlarged muscle is a suitable model for analyzing multiple physiological cellular responses in muscle–nerve–blood vessel units under continuous stretch stimulation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Pre-treatment neutrophil to lymphocyte ratio is elevated in epithelial ovarian cancer and predicts survival after treatment

Purpose  Inflammatory cells can both suppress and stimulate tumor growth, and the influence of inflammatory cells on clinical outcome has been the focus of many studies. The purpose of this study was to evaluate the effectiveness of the neutrophil to lymphocyte ratio (NLR), a measure of the systemic inflammatory response, as an additional discriminative biomarker in epithelial ovarian cancer and to determine whether it predicts survival and recurrence. Methods  We studied 192 patients with epithelial ovarian cancer, 173 with benign ovarian tumors, 229 with benign gynecologic disease, and 405 healthy controls. Serum CA125 levels and leukocyte counts according to subtypes were recorded prior to treatment in all study subjects. In epithelial ovarian cancer, the diagnostic usefulness of NLR, in combination with CA125, was evaluated. The correlation between NLR and overall and disease-free survival was analyzed using both univariate and multivariate analyses adjusting for the known prognostic factors (age, stage, cell type, and grade). Results  Preoperative NLR in ovarian cancer subjects (mean 6.02) was significantly higher than that in benign ovarian tumor subjects (mean 2.57), benign gynecologic disease subjects (mean 2.55), and healthy controls (mean 1.98) (P < 0.001). The sensitivity and specificity of NLR in detecting ovarian cancer was 66.1% (95% CI, 59.52–72.68%) and 82.7% (95% CI, 79.02–86.38%), respectively (cutoff value: 2.60). In early stage ovarian cancer, CA125 was not elevated in 19 out of 49 patients. Seven (36.8%) of these 19 patients were NLR positive. On Cox multivariate analysis, NLR positive, stage III/IV, and older age were independent poor prognostic factors, and being NLR positive was the most powerful predictive variable (Hazard Ratio = 8.42 [95% CI: 1.09–64.84], P = 0.041). Conclusions  Our findings provide evidence for the association between NLR and epithelial ovarian cancer. Preoperative NLR, in combination with CA125, may represent a simple and cost-effective method of identifying ovarian cancers, and an elevated NLR may predict an adverse outcome in ovarian cancer.