Sperm ultrastructure in the nudibranch genus Halgerda with reference to other Discodorididae and to Chromodorididae (Mollusca: Opisthobranchia)

Comparative sperm ultrastructure within the molluscan nudibranch genus Halgerda (Discodorididae) was examined for the first time using transmission electron microscopy (TEM), based on 17 of the 35 known species. In addition, observations on two other discodorids are made to facilitate outgroup comparison with Halgerda, including one species of Discodoris (D. boholiensis) and Asteronotus cespitosus (currently accepted as the closest sister taxon to Halgerda). Comparison was also made with some genera of the Chromodorididae in view of sperm similarities. Spermatozoa of all species examined were of the complex, helical, elongate ( approximately 300-400 micro m) type characteristic of most heterobranch gastropods. These cells exhibit the following discrete regions (in anteroposterior sequence) : an acrosomal complex (composed of a rounded, membrane-bound vesicle and a column-like pedestal); a solid, helical nucleus; an elongate, helical midpiece (composed of an axoneme and associated nine coarse fibers, an enveloping mitochondrial derivative of matrix, and paracrystalline materials and glycogen helix); an annular complex; and a short glycogen piece. Of these regions, the midpiece is by far the longest, occupying over 90% of the total sperm length. Comparison with other members of the radula-bearing cryptobranch dorids reveals several sperm similarities to other genera in the clade, particularly those of other Discodorididae and also with the Chromodorididae. Comparison with previously studied genera reveals noteworthy sperm differences within the Discodorididae. The most notable differences are the internal structure of the acrosomal pedestal (long and homogeneous in Halgerda, Discodoris; short and homogeneous in Asteronotus; long and finely striated in Rostanga; oblong with angular electron-lucent striations in Jorunna) and the internal structure of the glycogen piece. The pronounced helical keels of most Halgerda and Discodoris nuclei contrast with the weakly helical nucleus of Asteronotus. Sperm features alone do not provide a means of defining the genus Halgerda or the family Discodorididae nor do they support the monophyletic status of the caryophyllidia-bearing dorids. Important sperm characters such as the acrosome, nucleus, and midpiece can often still be determined from specimens that have been initially fixed in formalin, then stored in ethanol for extended periods of time (i.e., museum material). Of all sperm features, the mitochondrial derivative of the midpiece is the most resistant to long-term fixation : the survival of acrosomal, nuclear, and axonemal components is variable, presumably a factor of prefixation autolysis, varied primary fixation times and temperatures, formalin quality, and duration of alcohol storage.     

Improving vanadium stress tolerance of watermelon by grafting onto bottle gourd and pumpkin rootstock

Vanadium (V) is a transition metal found in the Earth crust. V adversely affects plant growth and development. Besides several other management practices, grafting of scion cultivars onto appropriate rootstock provides a suitable solution. Grafting is an important agro-technical procedure utilized to enhance the capacity of plants to tolerate biotic and abiotic stresses. In this study, watermelon was grafted onto bottle gourd and pumpkin rootstock, and self-grafted watermelon plants were utilized as a control. V was applied at the rate of 50 mg/L under hydroponic conditions. The result showed that V application substantially reduces the growth of watermelon plants, however, grafting of watermelon onto bottle gourd and pumpkin rootstock improves V stress tolerance of watermelon by reducing the V concentration in leaf tissues, improving the relative chlorophyll content (SPAD index) and photosynthetic assimilation, up-regulating the expression of SOD (Cla008698, Cla0012125, Cla009820 and Cla001158), glutathione S-transferase (Cla013224) and glutathione peroxidase (Cla021039) genes in the leaves, and enhancing the activities of antioxidant enzymes (SOD, CAT). The scanning electron microscopy (SEM) of the root tips showed that minimal damage of roots was observed for pumpkin roots compared with the roots of watermelon and bottle gourd under V stress conditions. So far as we know, these results are the first evidence that grafting mitigates V stress in plants.     

Isorhamnetin Inhibits Proliferation and Invasion and Induces Apoptosis through the Modulation of Peroxisome Proliferator-activated Receptor γ Activation Pathway in Gastric Cancer

Gastric cancer (GC) is a lethal malignancy and the second most common cause of cancer-related deaths. Although treatment options such as chemotherapy, radiotherapy, and surgery have led to a decline in the mortality rate due to GC, chemoresistance remains as one of the major causes for poor prognosis and high recurrence rate. In this study, we investigated the potential effects of isorhamnetin (IH), a 3′-O-methylated metabolite of quercetin on the peroxisome proliferator-activated receptor γ (PPAR-γ) signaling cascade using proteomics technology platform, GC cell lines, and xenograft mice model. We observed that IH exerted a strong antiproliferative effect and increased cytotoxicity in combination with chemotherapeutic drugs. IH also inhibited the migratory/invasive properties of GC cells, which could be reversed in the presence of PPAR-γ inhibitor. We found that IH increased PPAR-γ activity and modulated the expression of PPAR-γ regulated genes in GC cells. Also, the increase in PPAR-γ activity was reversed in the presence of PPAR-γ-specific inhibitor and a mutated PPAR-γ dominant negative plasmid, supporting our hypothesis that IH can act as a ligand of PPAR-γ. Using molecular docking analysis, we demonstrate that IH formed interactions with seven polar residues and six nonpolar residues within the ligand-binding pocket of PPAR-γ that are reported to be critical for its activity and could competitively bind to PPAR-γ. IH significantly increased the expression of PPAR-γ in tumor tissues obtained from xenograft model of GC. Overall, our findings clearly indicate that antitumor effects of IH may be mediated through modulation of the PPAR-γ activation pathway in GC.     

The effect of carbamazepine on bone structure and strength in control and osteogenesis imperfecta (Col1a2 +/p.G610C ) mice

The inherited brittle bone disease osteogenesis imperfecta (OI) is commonly caused by COL1A1 and COL1A2 mutations that disrupt the collagen I triple helix. This causes intracellular endoplasmic reticulum (ER) retention of the misfolded collagen and can result in a pathological ER stress response. A therapeutic approach to reduce this toxic mutant load could be to stimulate mutant collagen degradation by manipulating autophagy and/or ER‐associated degradation. Since carbamazepine (CBZ) both stimulates autophagy of misfolded collagen X and improves skeletal pathology in a metaphyseal chondrodysplasia model, we tested the effect of CBZ on bone structure and strength in 3‐week‐old male OI Col1a2 ^+/p.G610C and control mice. Treatment for 3 or 6 weeks with CBZ, at the dose effective in metaphyseal chondrodysplasia, provided no therapeutic benefit to Col1a2 ^+/p.G610C mouse bone structure, strength or composition, measured by micro‐computed tomography, three point bending tests and Fourier‐transform infrared microspectroscopy. In control mice, however, CBZ treatment for 6 weeks impaired femur growth and led to lower femoral cortical and trabecular bone mass. These data, showing the negative impact of CBZ treatment on the developing mouse bones, raise important issues which must be considered in any human clinical applications of CBZ in growing individuals.     

Improvement of biohydrogen production by Enterobacter cloacae IIT-BT 08 under regulated pH

The present study investigates the effect of pH and intermediate products formation on biological hydrogen production using Enterobacter cloacae IIT-BT 08. Initial pH was found to have a profound effect on hydrogen production potential, while regulating the pH 6.5 throughout the fermentation was found to increase the cumulative hydrogen production rate and yield significantly. Modified Gompertz equation was used to fit the cumulative hydrogen production curves to obtain the hydrogen production potential P, the hydrogen production rate R and lag phase λ. At regulated pH 6.5, higher H(2) yield (3.1molH(2)mol(-1) glucose), specific hydrogen production potential (798.1mL/g) and specific rate of H(2) production (72.1mLL(-1)h(-1)g(-1)) were obtained. The volatile fatty acid profile showed butyrate, ethanol and acetate as the major end metabolites of fermentation under the operating pH conditions tested; however, their pattern of distribution was pH dependent. At the optimum pH of 6.5, the acetate to butyrate ratio (A/B ratio) was found to be higher than that at any other pH. The study also investigates the effect of sodium ions on biohydrogen production potential. It was also found that sodium ion concentration up to 250mM enhanced the hydrogen production potential; however, any further increase in the metal ion concentration had an inhibitory effect.     

Competency for nonsense-mediated reduction in collagen X mRNA is specified by the 3' UTR and corresponds to the position of mutations in Schmid metaphyseal chondrodysplasia

Nonsense-mediated decay (NMD) is a eukaryotic cellular RNA surveillance and quality-control mechanism that degrades mRNA containing premature stop codons (nonsense mutations) that otherwise may exert a deleterious effect by the production of dysfunctional truncated proteins. Collagen X (COL10A1) nonsense mutations in Schmid-type metaphyseal chondrodysplasia are localized in a region toward the 3' end of the last exon (exon 3) and result in mRNA decay, in contrast to most other genes in which terminal-exon nonsense mutations are resistant to NMD. We introduce nonsense mutations into the mouse Col10a1 gene and express these in a hypertrophic-chondrocyte cell line to explore the mechanism of last-exon mRNA decay of Col10a1 and demonstrate that mRNA decay is spatially restricted to mutations occurring in a 3' region of the exon 3 coding sequence; this region corresponds to where human mutations have been described. This localization of mRNA-decay competency suggested that a downstream region, such as the 3' UTR, may play a role in specifying decay of mutant Col10a1 mRNA containing nonsense mutations. We found that deleting any of the three conserved sequence regions within the 3' UTR (region I, 23 bp; region II, 170 bp; and region III, 76 bp) prevented mutant mRNA decay, but a smaller 13 bp deletion within region III was permissive for decay. These data suggest that the 3' UTR participates in collagen X last-exon mRNA decay and that overall 3' UTR configuration, rather than specific linear-sequence motifs, may be important in specifying decay of Col10a1 mRNA containing nonsense mutations.