Shell occupation as a limiting factor for Pagurus brevidactylus (Stimpson, 1859) in the Marine State Park of Laje de Santos,Brazil

Hermit crabs are soft-abdomen decapods. They depend upon gastropod shells for protection, with the latter influencing growth rate, mortality and reproduction. The present work aims to provide information about the biology and reproduction of Pagurus brevidactylus in a conservation area in Brazilian southeastern littoral. The material was sampled through active searching by SCUBA diving and refuge traps. We analyzed population structure, fecundity, reproductive output (RO), reproductive periodicity and shell utilization for P. brevidactylus. In total, 54 males, 18 non-ovigerous females, 34 ovigerous females and 10 juveniles were sampled. The females had a fecundity of 69.5 ± 65 eggs, which was lower than that compared to other populations from different localities. The RO ranged from 1.48% to 63.04%, with a mean of 26.75 ± 18.23%. There was a positive relationship between egg number and female size. The animals had continuous reproduction, but they reached smaller maximum sizes when compared with other populations. The shell occupation pattern was also different from other localities, the shells of Phrontis alba being the most occupied; this shell has a smaller size when compared to others that P. brevidactylus occupies in other localities. Therefore, P. alba could have had limited the growth and reproduction of P. brevidactylus.     

Global analysis of the apple fruit microbiome: are all apples the same?

We present the first worldwide study on the apple (Malus × domestica) fruit microbiome that examines questions regarding the composition and the assembly of microbial communities on and in apple fruit. Results revealed that the composition and structure of the fungal and bacterial communities associated with apple fruit vary and are highly dependent on geographical location. The study also confirmed that the spatial variation in the fungal and bacterial composition of different fruit tissues exists at a global level. Fungal diversity varied significantly in fruit harvested in different geographical locations and suggests a potential link between location and the type and rate of postharvest diseases that develop in each country. The global core microbiome of apple fruit was represented by several beneficial microbial taxa and accounted for a large fraction of the fruit microbial community. The study provides foundational information about the apple fruit microbiome that can be utilized for the development of novel approaches for the management of fruit quality and safety, as well as for reducing losses due to the establishment and proliferation of postharvest pathogens. It also lays the groundwork for studying the complex microbial interactions that occur on apple fruit surfaces.     

Progesterone modulation of α5 nAChR subunits influences anxiety‐related behavior during estrus cycle

Smokers often report an anxiolytic effect of cigarettes. In addition, stress‐related disorders such as anxiety, post‐traumatic stress syndrome and depression are often associated with chronic nicotine use. To study the role of the α5 nicotinic acetylcholine receptor subunit in anxiety‐related responses, control and α5 subunit null mice (α5^?/?) were subjected to the open field activity (OFA), light–dark box (LDB) and elevated plus maze (EPM) tests. In the OFA and LDB, α5^?/? behaved like wild‐type controls. In the EPM, female α5^?/? mice displayed an anxiolytic‐like phenotype, while male α5^?/? mice were undistinguishable from littermate controls. We studied the hypothalamus–pituitary–adrenal axis by measuring plasma corticosterone and hypothalamic corticotropin‐releasing factor. Consistent with an anxiolytic‐like phenotype, female α5^?/? mice displayed lower basal corticosterone levels. To test whether gonadal steroids regulate the expression of α5, we treated cultured NTera 2 cells with progesterone and found that α5 protein levels were upregulated. In addition, brain levels of α5 mRNA increased upon progesterone injection into ovariectomized wild‐type females. Finally, we tested anxiety levels in the EPM during the estrous cycle. The estrus phase (when progesterone levels are low) is anxiolytic‐like in wild‐type mice, but no cycle‐dependent fluctuations in anxiety levels were found in α5^?/? females. Thus, α5‐containing neuronal nicotinic acetylcholine receptors may be mediators of anxiogenic responses, and progesterone‐dependent modulation of α5 expression may contribute to fluctuations in anxiety levels during the ovarian cycle.     

Small-spatial scale changes in productivity of suprabenthic and infaunal crustaceans at the continental shelf of Ebro Delta (western Mediterranean)

Production (P) and production/biomass ratio (P/B) were estimated from 21 species of peracarid and eucarid crustaceans belonging to two different compartments (infauna: 10 species and suprabenthos: 11 species) using the Hynes size–frequency method. Calculations were based on 7 cruises performed between December 2002 and November 2003 in the continental shelf of the Ebro river delta (ED, Catalan Sea: northwestern Mediterranean). Within ED, P and P/B were compared between two neighbouring sites, one located on 47 m (S1), the other at 61 m (S2). The possible effects of natural variability on production were considered. Sediments in ED were muddy (%clay between 40 and 65%). No significant trend in production comparing S1 and S2 was detected, with 50% of species showing higher P value in S1, and 50% in S2. A significant trend emerged from P/B estimates, with 18 of 21 species showing higher P/B at S1. Similarly significant trends for infauna and suprabenthos were found after analyzing both compartments separately. It is suggested that the more significant P/B found on S1 both among infauna and suprabenthos could be caused by the higher temperature and organic matter content (%TOC) at S1. In multi-linear regression (MLR) models, differences in P between S1 and S2 were greater with increasing differences in the density of species (RD) between sites. Differences were greater in infauna than in suprabenthos, and greater among rare species (those with low dominance, %D). P/B differences between S1 and S2 were mainly explained by %D and RD, and to a lesser extent by differences between sites in the mean size of species (RW). In other words changes in P and P/B were not explained by removal of large size specimens. Some trawling activity occurred at S2, and it may alter the habitat of small macrofauna. In addition to natural variability, we discussed the possible influence of trawling disturbance on P and P/B, bearing in mind the feeding type, mobility, and dispersal capability of species. We suggest that amphipods of the genus Ampelisca, showing higher P/B on S1, characterized by low mobility (probably tube-dwellers), low trophic level (e.g. filter feeding strategies) and low dispersal capability (not free larvae), could be especially vulnerable to trawling impact.     

Lymphokine-induced cytotoxic cell generation in thymus and spleen cell cultures

The effect of a supernatant (SN-A) obtained from PMA-stimulated IL-2 producing EL-4 cells on cytotoxic cell induction in thymocyte and splenocyte cultures was evaluated. SN-A, but not recombinant IL-2 alone, induced cytotoxic cell differentiation in thymus cell cultures, thus indicating that factors distinct from IL-2 are required for effector cell generation. INF-gamma takes part in the process, and Ia+ accessory cell presence is also strictly required in thymus cultures for lymphokine-induced cytotoxic cell generation. Cytotoxic activity in thymocyte cultures was due only to Thy 1+ Lyt 2+ cells having a broad spectrum of target cell specificity, while in spleen cell cultures an effector population with NK activity was also generated.     

Histochemical localization of monoamines and cholinesterases in Mytilus pedal ganglion

Summary The pedal ganglion is a peripheral ganglion which gives rise to the innervation for both the somatic and visceral organs of the Mytilus foot. In the present study, different histofluorescence methods for the demonstration of monamines (formaldehyde-glutaraldehyde followed by polyethylene glycol embedding; aluminium-formaldehyde; Falck) and acetylcholinesterase histochemistry were applied in order to characterize the neuronal population of the ganglion. The fluorescence methods employed showed that the cortical region of the pedal ganglion is composed of roundish cells; these mainly contained an orange autofluorescent pigment. Yellow-fluorescing cells were scattered in the anterior region of the cortex, but they were more numerous and arranged in clusters in the posterior region. Greenfluorescing cells were mainly located at the border between the cortex and neuropile and in the neuropile itself, where a rich plexus of beaded green-fluorescing fibres was also present. Of the three methods, that using formaldehydeglutaraldehyde followed by embedding in polyethylene glycol gave the best preservation of morphological details. Acetylcholinesterase histochemistry showed the presence of positive cells and fibres mainly in the anterior region of the ganglion.     

Biochemical evidence for chemical and/or topographic differences in the lipoperoxidative processes induced by CCl4 and iron

Isolated rat hepatocytes, treated with CCl4 or ADP-Fe3+ complex show an enhanced lipid peroxidation and a decreased glucose 6-phosphatase activity. Lipid peroxidation is much more stimulated by ADP-Fe3+ or Fe3+ than by CCl4, when the metal and the haloalkane are used at a similar concentration. Increasing rates of lipid peroxidation in the different experimental conditions do not correlate with the degree of glucose 6-phosphatase inactivation, which is produced by CCl4 and not by a similar amount of ferric iron. In the case of iron, its intracellular concentration must be higher to give the enzyme inactivation exerted by CCl4. Higher intracellular levels of iron are reached when the metal is added to the cell suspension together with ADP. Under these conditions there is inactivation of glucose 6-phosphatase. Possible mechanisms accounting for a different enzyme sensitivity to iron and CCl4 are discussed.     

Selective failure of accessory cell function in Moloney murine leukemia virus-tolerant mice

Accessory cell activity of spleen cells from M-MuLV neonatally injected (tolerant) mice was studied to evaluate their ability to take part in in vitro CTL generation against tumor-associated antigens induced by M-MSV. In contrast with accessory cell activity in normal spleen cells, spleen cells from M-MuLV-tolerant mice are unable to reconstitute the in vitro virus-specific CTL generation of M-MSV immune, Ia-depleted spleen cells. A selective defect seems to characterize M-MuLV-tolerant mice as their spleens constitute a good source of accessory cells for alloantigen CTL generation.     

Isolation and Preliminary Characterization of ATPase from Olive Calli Grown at Different Auxin/Cytokinin Ratio

ATPase activity was studied in calli from olive (Olea europaea L.) petioles cultured in media modified in their auxin/cytokinin ratio in order to induce different morphogenetic responses. Addition of 0.54 μM α-naphthaleneacetic acid (NAA) or 14 μM zeatin (ZEA) did not induce any morphogenesis in calli and proton pump activity in vivo was very low, while calli produced roots at 27 or 11 μM NAA + 0.28 μM ZEA and possessed clearly detectable proton pump activity. ATPase activity associated with microsomes isolated by differential centrifugation from different callus cultures had the same pH optimum and similar sensitivity toward nitrate and azide. However, microsomes isolated from non-morphogenetic calli had higher specific ATPase activity which was very poorly (6 %) inhibited by vanadate. Also, the fractionation of these microsomes on a continuous sucrose gradient showed two peaks of ATPase activity, the more pronounced one co-purifying with the Golg i marker enzyme, Triton-stimulated UDPase activity, suggesting thus the presence of very high ATPase activity in Golgi secretory vesicles. On the contrary, ATPase activity of microsomes from calli producing roots was more sensitive to vanadate (30 - 40 % inhibition). Furthermore, the component of ATPase activity attributable to Golgi secretory vesicles was less abundant. This revised version was published online in July 2006 with corrections to the Cover Date.