Comparative oogenesis in cardinal fishes (Apogonidae,Perciformes), with special focus on the adaptive structures of the egg envelopes

The present study compares gonad structure and oogenesis in 30 species of cardinal fish (Apogonidae) from the Indo-Pacific region. In all of the species studied the ovaries are bilobed, with each lobe possessing ovigerous lamellae whose numbers and dimensions increase concomitantly with growth of the fish and reproductive stage, and correlate with the total dimensions of the particular species. In species of the genus Siphamia, the ovarian lobes are associated with a fat body that is not found in species of the other genera studied. Some of the species studied (Siphamia spp.; Archamia spp.) demonstrate group-synchronized maturation of eggs, possibly with only one spawn per reproduction season. However, most of the Apogon spp., and other genera, have unsynchronized cycles, a characteristic of multiple spawners. The various stages of previtellogenic and vitellogenic development are similar in the different species, but differ in timing and dimensions of the oocytes around which the morphogenesis of the egg envelope (chorion) and follicle begins. Differentiation of the egg envelope and follicle cells parallels the vitellogenic stages of egg development. The number of eggs was found to correlate positively with the length of the body and ovary of the fish, whereas egg diameter was found to correlate negatively with body length. The surface of the egg envelope bears ridges that form patterns of various types, whose structures and dimensions seem to be species-specific, and which in most species converge upon the single micropyle on the animal pole. The exposed ridge mazes include a special fibrous web that anchors in the micropyle. The production and importance of these ridges, as well as the correlations between egg numbers per spawn, egg dimensions, and the oral dimensions of the paternal male, are discussed.     

The effect of intra- and interspecific aggression on patch residence time in Negev Desert gerbils: a competing risk analysis

We observed patch-use behavior by two gerbil species in a fieldsetting and investigated how aggression and intrinsic decision-makinginteract to influence patch residence times. Results were interpretedby using a competing risk analysis model, which uniquely enabledus to estimate the intrinsic patch-leaving decisions independentlyof external interruptions of foraging bouts by aggression. Theexperiment was conducted in two 1-ha field enclosures completelysurrounded by rodent-proof fences and included allopatric (onlyGerbillus andersoni allenbyi) and sympatric (G. a. allenbyiand G. pyramidum) treatments. We predicted that increased foodpatch quality (i.e., habitat quality) should decrease intrinsicpatch-leaving rates and increase rates of aggressive interactionsinvolving the forager feeding in the patch (i.e., the occupantindividual). We also anticipated that increasing populationdensity should result in an increase in the rate of aggressiveinteractions involving the occupant individual. Our resultssupported the first two predictions, indicating a trade-offbetween foraging and aggression. However, the third predictionwas realized only for G. a. allenbyi in allopatry. Furthermore,in allopatry, occupant G. a. allenbyi individuals with highcompetitive ranks were involved in aggressive interactions atlower rates than those with low competitive ranks. However,in sympatry, patch-use behavior of occupant G. a. allenbyi individualswas mainly influenced by aggressive behavior of G. pyramidum,which did not respond to their competitive rank. Thus, it shouldpay less for G. a. allenbyi to be aggressive in sympatric populations.The observed reduction in intraspecific aggression among individualG. a. allenbyi in the presence of G. pyramidum supports thisassertion. We suggest that this reduction likely weakens thenegative effect of intra- and interspecific density on the percapita growth rate of G. a. allenbyi. Because this would changethe slope of the isocline of G. a. allenbyi, it could be animportant mechanism promoting coexistence when habitat selectionis constrained.     

p27 and salivary cancer

This study examined p27 expression in a cohort of salivary malignancies (n = 74) for a prolonged period (20 years). Reduction of p27 expression was found to be a most powerful predictor for poor survival and more so when the tumor concurrently expressed high levels of p53, TUNEL and heparanase markers, dramatically dropping the patient survival probability to 0! While no patient whose tumor-staining profile included: p27 > 50%, p53 = 0, TUNEL = 0 and heparanase = 0, died of the disease during the 20-year follow up, the median of survival of the group with p27 ≤ 50%, p53 > 0, TUNEL > 0 and heparanase > 0 was only 39 months. The survival probabilities of these two groups at 5 years were 100 and 50%, respectively, and at 20 years they were 100 and 0%, respectively (P = 0.05). Significant p27 reduction also resulted in significantly larger tumor size (T value), higher spread of neck metastasis and extra capsular spread and in more advanced disease (higher stage). Significant correlation rates were found between age and poor survival, age and reduced p27 expression, and reduced p27 expression and other general co-existing malignancies, indicating p27 reduction as part of a general phenomenon—age related mutagenesis. Significantly more extensive therapy applied to patients with salivary reduced-p27 tumors could not prevent the rise in mortality rate, questioning the justification for extensive therapy which is naturally accompanied by higher morbidity. Additional therapeutic tools for fighting salivary cancer, possibly based on the new understanding of the p27, p53, TUNEL and heparanase carcinogenic network, are necessary.     

Inhibition of inosine monophosphate dehydrogenase reduces adipogenesis and diet-induced obesity

We previously described a putative role for inosine monophosphate dehydrogenase (IMPDH), a rate-limiting enzyme in de novo guanine nucleotide biosynthesis, in lipid accumulation. Here we present data which demonstrate that IMPDH activity is required for differentiation of preadipocytes into mature, lipid-laden adipocytes and maintenance of adipose tissue mass. In 3T3-L1 preadipocytes inhibition of IMPDH with mycophenolic acid (MPA) reduced intracellular GTP levels by 60% (p < 0.05) and blocked adipogenesis (p < 0.05). Co-treatment with guanosine, a substrate in the salvage pathway of nucleotide biosynthesis, restored GTP levels and adipogenesis demonstrating the specificity of these effects. Treatment of diet-induced obese mice with mycophenolate mofetil (MMF), the prodrug of MPA, for 28 days did not affect food intake or lean body mass but reduced body fat content (by 36%, p = 0.002) and adipocyte size (p = 0.03) and number. These data suggest that inhibition of IMPDH may represent a novel strategy to reduce adipose tissue mass.     

Design and synthesis of substituted quinolines as novel and selective melanin concentrating hormone antagonists as anti-obesity agents

A novel series of substituted quinoline analogs were designed and synthesized as potent and selective melanin concentrating hormone (MCH) antagonists. These analogs show potent (nM) activity (12a-k) with a moderate selectivity. Conversely, the conformationally constrained thienopyrimidinone analogs (18a-g) showed improved activity in MCH-1R and selectivity over 5HT2C.     

TLR2 Mediates Recognition of Live Staphylococcus epidermidis and Clearance of Bacteremia

Background

Staphylococcus epidermidis (SE) is a nosocomial pathogen that causes catheter-associated bacteremia in the immunocompromised, including those at the extremes of age, motivating study of host clearance mechanisms. SE-derived soluble components engage TLR2; but additional signaling pathways have also been implicated, and TLR2 can play complex, at times detrimental, roles in host defense against other Staphylococcal spp. The role of TLR2 in responses of primary blood leukocytes to live SE and in clearance of SE bacteremia, the most common clinical manifestation of SE infection, is unknown.

Methodology/Principal Findings

We studied TLR2-mediated recognition of live clinical SE strain 1457 employing TLR2-transfected cells, neutralizing anti-TLR antibodies and TLR2-deficient mice. TLR2 mediated SE-induced cytokine production in human embryonic kidney cells, human whole blood and murine primary macrophages, in part via recognition of a soluble TLR2 agonist. After i.v. challenge with SE, early (1 h) cytokine/chemokine production and subsequent clearance of bacteremia (24–48 h) were markedly impaired in TLR2-deficient mice.

Conclusions/Significance

TLR2 mediates recognition of live SE and clearance of SE bacteremia in vivo.     

Small‐scale spatial variability in the distribution of ectomycorrhizal fungi affects plant performance and fungal diversity

The effects of spatial heterogeneity in negative biological interactions on individual performance and species diversity have been studied extensively. However, little is known about the respective effects involving positive biological interactions, including the symbiosis between plants and ectomycorrhizal (EM) fungi. Using a greenhouse bioassay, we explored how spatial heterogeneity of natural soil inoculum influences the performance of pine seedlings and composition of their root‐associated EM fungi. When the inoculum was homogenously distributed, a single EM fungal taxon dominated the roots of most pine seedlings, reducing the diversity of EM fungi at the treatment level, while substantially improving pine seedling performance. In contrast, clumped inoculum allowed the proliferation of several different EM fungi, increasing the overall EM fungal diversity. The most dominant EM fungal taxon detected in the homogeneous treatment was also a highly beneficial mutualist, implying that the trade‐off between competitive ability and mutualistic capacity does not always exist.     

The effect of habitat temperature on serum antifreeze glycoprotein (AFGP) activity in Notothenia rossii (Pisces: Nototheniidae) in the Southern Ocean

The marble notothen, Notothenia rossii, is widely distributed around the waters of sub-Antarctic islands in the Southern Ocean and is exposed to different temperatures that range from ?1.5 to 8 °C. This study investigates whether the different environmental conditions experienced by N. rossii at different latitudes in the Southern Ocean affect the levels of its blood serum antifreeze glycoprotein (AFGP). N. rossii specimens were collected from four localities, including the Ob’ Seamount in the Indian Ocean sector, and South Georgia Island, South Shetland Islands and Dallman Bay in the Atlantic Ocean sector. Serum AFGP activity was determined in terms of thermal hysteresis, i.e. the difference between the equilibrium melting and non-equilibrium freezing points (f.p.s.). Among the four populations, the Ob’ Seamount specimen had the lowest serum AFGP activity (0.44 °C) and concentration (4.88 mg/mL), and the highest non-equilibrium f.p. (?1.39 °C). These results are consistent with the warmer, ice-free waters around the Ob’ Seamount. The other three higher latitude populations have 2–3 times greater serum AFGP activity and concentration, and much lower non-equilibrium f.p.s. In contrast, the physiological profiles of serum AFGP size isoforms revealed that all N. rossii populations, including the Ob’ Seamount specimen, possess an extensive complements of AFGP proteins. Isoform variation was observed, especially in the large size isoforms (AFGPs 1–5), when compared to AFGP of the high Antarctic Dissostichus mawsoni. The lower levels of AFGP and the absence of some of the large isoforms are likely responsible for higher non-equilibrium f.p.s. of the Ob’ seamount specimen.     

Scientists@Home: What Drives the Quantity and Quality of Online Citizen Science Participation?

Online citizen science offers a low-cost way to strengthen the infrastructure for scientific research and engage members of the public in science. As the sustainability of online citizen science projects depends on volunteers who contribute their skills, time, and energy, the objective of this study is to investigate effects of motivational factors on the quantity and quality of citizen scientists'' contribution. Building on the social movement participation model, findings from a longitudinal empirical study in three different citizen science projects reveal that quantity of contribution is determined by collective motives, norm-oriented motives, reputation, and intrinsic motives. Contribution quality, on the other hand, is positively affected only by collective motives and reputation. We discuss implications for research on the motivation for participation in technology-mediated social participation and for the practice of citizen science.