Antimicrobial actions of dual oxidases and lactoperoxidase

The NOX/DUOX family of NADPH oxidases are transmembrane proteins generating reactive oxygen species as their primary enzymatic products. NADPH oxidase (NOX) 1–5 and Dual oxidase (DUOX) 1 and 2 are members of this family. These enzymes have several biological functions including immune defense, hormone biosynthesis, fertilization, cell proliferation and differentiation, extracellular matrix formation and vascular regulation. They are found in a variety of tissues such as the airways, salivary glands, colon, thyroid gland and lymphoid organs. The discovery of NADPH oxidases has drastically transformed our view of the biology of reactive oxygen species and oxidative stress. Roles of several isoforms including DUOX1 and DUOX2 in host innate immune defense have been implicated and are still being uncovered. DUOX enzymes highly expressed in the respiratory and salivary gland epithelium have been proposed as the major sources of hydrogen peroxide supporting mucosal oxidative antimicrobial defenses. In this review, we shortly present data on DUOX discovery, structure and function, and provide a detailed, up-to-date summary of discoveries regarding antibacterial, antiviral, antifungal, and antiparasitic functions of DUOX enzymes. We also present all the literature describing the immune functions of lactoperoxidase, an enzyme working in partnership with DUOX to produce antimicrobial substances.     

The role of progeny quality and male size in the nesting success of smallmouth bass: integrating field and laboratory studies

Smallmouth bass display size-specific variation in reproductive success with larger brood-guarding males in a population more likely to rear offspring to independence than smaller individuals. The exact mechanisms responsible for this size-specific increase in reproductive output have yet to be identified. To assist in this process, we investigated the relationship between the size of brood-guarding male smallmouth bass and offspring quality (in this case, egg physiology, egg morphology, egg size, hatching success and lab survival). Further, we examined how factors such as egg physiology, egg morphology and egg size influenced reproductive success in the wild and hatching success in a controlled laboratory environment. Nesting male smallmouth bass that successfully reared their offspring to independence spawned earliest in the nesting period were the largest individuals, and guarded eggs with greater concentrations of cortisol compared to males that abandoned their offspring prematurely. Offspring survival in the laboratory was not correlated with offspring survival in the wild, indicating that caution should be used interpreting studies that attempt to relate laboratory-derived survival metrics to the wild. Together, results demonstrate size-specific differences in offspring quality for nesting smallmouth bass, which are correlated with higher concentrations of cortisol in eggs. However, hatching success under laboratory conditions was dissimilar to nesting success in the field relative to cortisol concentrations.     

Morphogenic Regulation of Pathotoxin Synthesis in Cochliobolus carbonum

The fungus Cochliobolus carbonum causes leaf spot disease of maize. Highly virulent isolates of the pathogen produce a host-selective, peptide toxin that is active against susceptible genotypes of maize. Prior to infection, spores must germinate and differentiate appressoria, structures specialized for leaf penetration. Analysis of spore germination fluids by plasma desorption mass spectrometry, which allowed detection of as little as 0.5 ng toxin, revealed that spores induced to form appressoria in vitro synthesized and released the toxin at a time coincident with maturation of appressoria. Spores incubated under conditions that did not induce appressorium formation failed to produce toxin. These observations indicate that synthesis of the host-selective toxin, which is essential for successful pathogenesis of maize by C. carbonum, is regulated by infection-related morphogenesis.     

Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.     

Detection of somatic mutations in vivo in lung fibroblasts, I. Spontaneous frequencies in Chinese hamsters and F344 rats.

The frequency of mutant cells observed in a series of experiments in which primary cells were isolated from untreated or solvent control animals are reported. The mutants detected are thioguanine-resistant lung fibroblasts isolated de novo from Chinese hamsters or Fischer 344 rats. The results in the two species were very similar. The distribution of mutant colonies in cells isolated from untreated animals is not random (Poissonian) but rather shows an excess of mutant clusters. No significant difference was detected between males and females. The results provide the information necessary to define the appropriate conditions for the negative controls for a routine assay for mutations induced in vivo.     

Dental and cranial variation in living Indriidae

Four species of Indriidae are extant in Madagascar. We have studied large samples of each of these to characterize dental and cranial variation, and to estimate the degree of sexual dimorphism in the dentition and cranium. Two dental fields are apparent, characterized by reduced variability: (1) a canine field centered on the upper canine and occluding caniniform lower premolar, and (2) a cheek tooth field centered on the second molars. No consistent pattern of sexual dimorphism was found in dental or cranial dimensions, and we conclude that none of the four species is sexually dimorphic. This lack of dental and cranial dimorphism is unusual in primates, and probably reflects the relatively limited aggressive behavior and the lack of male dominance in Indriidae.     

Trends in lizard translocations in New Zealand between 1988 and 2013

There is growing concern about mitigation-driven translocations that move animals from anthropogenic threats at donor sites because of their failure rate and lack of application of scientific principles and best practice. We reviewed all known lizard translocations in New Zealand between 1988 and 2013 and identified 85 translocations of 30 lizard taxa to 46 release sites. Most translocations (62%) were motivated by conservation goals for the species or the release site, and one-third were mitigation-driven translocations, typically motivated by habitat loss due to development. Mitigation-driven translocations began in 2003, and since that time have equalled the number of conservation-motivated translocations. Conservation-motivated translocations usually released lizards on islands without mammalian predators, whereas mitigation-driven translocations usually relocated lizards to mainland sites with introduced predators. Long-term monitoring has been sparse and often rudimentary. Eight lizard translocations have recorded population growth, including one mitigation-driven translocation that was into a fenced reserve. Research on commonly used management techniques to mitigate human-related impacts is recommended to establish whether these techniques benefit lizards in the long term.