Symbiodinium clade C dominates zooxanthellate corals (Scleractinia) in the temperate region of Japan

Endosymbiotic algae of the genus Symbiodinium have been divided into nine clades (A-I) following genetic classification; some clades are known to have physiological properties that enable the coral hosts to adapt to different environmental conditions. To understand the relationships of coral-alga symbioses, we focused on Symbiodinium diversity in zooxanthellate corals living under the severe environmental conditions of the temperate region (30°-35°N) of Japan. We investigated Symbiodinium clades in 346 colonies belonging to 58 coral species from six locations. We then selected three coral species-Acropora hyacinthus, Acropora japonica, and Cyphastrea chalcidicum-to investigate whether Symbiodinium clades changed during winter or summer over the course of year (May 2009-Apr 2010) in Tanabe Bay, Japan. Three Symbiodinium clades (C, D, and F) were detected in corals in the temperate region. Notably, 56 coral species contained Symbiodinium clade C. Oulastrea crispata predominantly contained clade D, but traces of clade C were also detected in all samples. The temperate-specific species Alveopora japonica contained clades C and F simultaneously. Seasonal change of symbiont clades did not occur in the three coral species during the investigation period where SSTs range on 12.5-29.2°C. However, we found Acropora (2 spp.) and Cyphastrea (1 sp.) contained different subcladal types of clade C. These results reveal that most coral species harbored Symbiodinium clade C stably throughout the year, suggesting that Symbiodinium clade C shows low-temperature tolerance, and that two hypothetical possibilities; genetic differences of subcladal types generating physiological differences or wide physiological flexibility in the clade C.     

Monitoring the gestation period of rescued Formosan pangolin (Manis pentadactyla pentadactyla) with progesterone radioimmunoassay

Eight species of pangolin have been identified in the world. However, understanding of pangolin reproductive biology has been limited to fragmentary records. In this study, the concentration of serum progesterone in three pregnant and two nonpregnant rescued female Formosan pangolins (Manis pentadactyla pentadactyla) was monitored using a commercial progesterone radioimmunoassay kit. During gestation, the serum progesterone of pregnant pangolins A, B, and C remained at 28.5–55 ng/ml (n = 31 samples), 10.9–50.1 ng/ml (n = 34), and 12.4 and 33.5 ng/ml with a peak at 47.6 ng/ml (n = 19), respectively, whereas the serum progesterone of nonpregnant pangolins D and E remained at 1.99 ± 1.62 ng/ml (n = 80) and 2.27 ± 1.64 ng/ml (n = 27), respectively. From this study, it was found that female pangolin weighing as low as 2.14 kg was already capable of reproduction. For pregnant pangolins to give birth to viable offspring, their body weight must increase significantly, 63.89 and 134.0% in the study, from the time of inception or early pregnancy until parturition. In addition, study has found that both viable offspring were born fully developed and exceeded 80 g in weight. The period of gestation was found to be as short as 318 or longer than 372 days. Therefore, the Formosan pangolin should only be able to reproduce once a year. This study is the first insight into hormone assay for determining the gestation period of pangolin. Further investigations on the same subject are necessary to establish criteria for the recognition of reproductive status in pangolins. Zoo Biol 31:479–489, 2012. © 2011 Wiley Periodicals, Inc.     

Poly (ADP-ribose) polymerase plays an important role in intermittent hypoxia-induced cell death in rat cerebellar granule cells

Background

Episodic cessation of airflow during sleep in patients with sleep apnea syndrome results in intermittent hypoxia (IH). Our aim was to investigate the effects of IH on cerebellar granule cells and to identify the mechanism of IH-induced cell death.

Methods

Cerebellar granule cells were freshly prepared from neonatal Sprague-Dawley rats. IH was created by culturing the cerebellar granule cells in the incubators with oscillating O₂ concentration at 20% and 5% every 30 min for 1-4 days. The results of this study are based on image analysis using a confocal microscope and associated software. Cellular oxidative stress increased with increase in IH. In addition, the occurrence of cell death (apoptosis and necrosis) increased as the duration of IH increased, but decreased in the presence of an iron chelator (phenanthroline) or poly (ADP-ribose) polymerase (PARP) inhibitors [3-aminobenzamide (3-AB) and DPQ]. The fluorescence of caspase-3 remained the same regardless of the duration of IH, and Western blots did not detect activation of caspase-3. However, IH increased the ratio of apoptosis-inducing factor (AIF) translocation to the nucleus, while PARP inhibitors (3-AB) reduced this ratio.

Results

According to our findings, IH increased oxidative stress and subsequently leading to cell death. This effect was at least partially mediated by PARP activation, resulting in ATP depletion, calpain activation leading to AIF translocation to the nucleus.

Conclusions

We suggest that IH induces cell death in rat primary cerebellar granule cells by stimulating oxidative stress PARP-mediated calpain and AIF activation.     

Identification and characterization of collagen-binding activity in Streptococcus mutans wall-associated protein: a possible implication in dental root caries and endocarditis

Streptococcus mutans is implicated in coronal and dental root decay, and in endocarditis. Comparative study of the amino acid sequence of S. mutans 47 kDa wall-associated protein A (WapA) revealed a collagen-binding domain (CBD) at the N-terminal region. Recombinant AgA (WapA truncated at the carboxyterminal end) was isolated, biotin-labeled, and analyzed by Solid Phase Binding Assay. The results showed that biotin-labeled AgA bound significantly and in a dose-dependent manner to immobilized collagen type I, and to a lesser extent to fibronectin, but not to collagen type IV or laminin. Binding of biotin-labeled S. mutans cells to collagen-coated surfaces was significantly inhibited by antibody to WapA or AgA (P<0.001). The results obtained confirmed the collagen-binding activity of CBD in AgA and WapA, and suggested that WapA may be used, not only as a vaccine against coronal and dental root caries, but also against S. mutans-mediated endocarditis.     

Cell wall substrate specificity of six different lysozymes and lysozyme inhibitory activity of bacterial extracts

We have investigated the specificity of six different lysozymes for peptidoglycan substrates obtained by extraction of a number of gram-negative bacteria and Micrococcus lysodeikticus with chloroform/Tris-HCl buffer (chloroform/buffer). The lysozymes included two that are commercially available (hen egg white lysozyme or HEWL, and mutanolysin from Streptomyces globisporus or M1L), and four that were chromatographically purified (bacteriophage lambda lysozyme or LaL, bacteriophage T4 lysozyme or T4L, goose egg white lysozyme or GEWL, and cauliflower lysozyme or CFL). HEWL was much more effective on M. lysodeikticus than on any of the gram-negative cell walls, while the opposite was found for LaL. Also the gram-negative cell walls showed remarkable differences in susceptibility to the different lysozymes, even for closely related species like Escherichia coli and Salmonella Typhimurium. These differences could not be due to the presence of lysozyme inhibitors such as Ivy from E. coli in the cell wall substrates because we showed that chloroform extraction effectively removed this inhibitor. Interestingly, we found strong inhibitory activity to HEWL in the chloroform/buffer extracts of Salmonella Typhimurium, and to LaL in the extracts of Pseudomonas aeruginosa, suggesting that other lysozyme inhibitors than Ivy exist and are probably widespread in gram-negative bacteria.     

Tamoxifen protects against acute tumor necrosis factor alpha-induced cardiac injury via improving mitochondrial functions

Tamoxifen is the most commonly used antiestrogen for the treatment of breast cancer. Several clinical trials demonstrate that tamoxifen reduces the risk of heart disease and osteoporosis. However, the mechanism by which tamoxifen causes cardioprotection is unclear. Because increased levels of tumor necrosis factor alpha (TNFalpha) in tissue and/or plasma have been observed in virtually all forms of cardiac injury, we investigated whether tamoxifen prevents cardiac injury in a murine model of acute TNFalpha challenge. Five- to six-week-old female mice were injected (ip) with tamoxifen at 0.25 mg/kg daily for 3 or 7 days before receiving an injection of TNFalpha. Ultrastructural examination of cardiac tissues revealed remarkable protection against TNFalpha-induced mitochondrial damage in tamoxifen pretreated mice. Tamoxifen treatment significantly improved the mitochondrial respiratory function and enhanced superoxide-scavenging activity of mitochondria. These findings reveal a novel mitochondria-mediated mechanism by which tamoxifen exerts its cardiac protection effect against acute TNFalpha-induced heart injury.