Mitochondrial respiratory chain and creatine kinase activities following trauma brain injury in brain of mice preconditioned with N-methyl-d-aspartate

Traumatic brain injury (TBI) induces glutamatergic excitotoxicity through N-methyl-d-aspartate (NMDA) receptors, affecting the integrity of the mitochondrial membrane. Studies have pointed to mitochondria as the master organelle in the preconditioning-triggered endogenous neuroprotective response. The present study is aimed at understanding energy metabolism in the brains of mice after preconditioning with NMDA and TBI. For this purpose, male albino CF-1 mice were pre-treated with NMDA (75 mg/kg) and subjected to brain trauma. Mitochondrial respiratory chain and creatine kinase activities were assessed at 6 or 24 h after trauma. The mice preconditioned and subjected to TBI exhibited augmented activities of complexes II and IV in the cerebral cortex and/or cerebellum. Creatine kinase activity was also augmented in the cerebral cortex after 24 h. We suggest that even though NMDA preconditioning and TBI have similar effects on enzyme activities, each manage their response via opposite mechanisms because the protective effects of preconditioning are unambiguous. In conclusion, NMDA preconditioning induces protection via an increase of enzymes in the mitochondria.     

Low plant density enhances gene dispersal in the Amazonian understory herb Heliconia acuminata

In theory, conservation genetics predicts that forest fragmentation will reduce gene dispersal, but in practice, genetic and ecological processes are also dependent on other population characteristics. We used Bayesian genetic analyses to characterize parentage and propagule dispersal in Heliconia acuminata L. C. Richard (Heliconiaceae), a common Amazonian understory plant that is pollinated and dispersed by birds. We studied these processes in two continuous forest sites and three 1‐ha fragments in Brazil's Biological Dynamics of Forest Fragments Project. These sites showed variation in the density of H. acuminata. Ten microsatellite markers were used to genotype flowering adults and seedling recruits and to quantify realized pollen and seed dispersal distances, immigration of propagules from outside populations, and reproductive dominance among parents. We tested whether gene dispersal is more dependent on fragmentation or density of reproductive plants. Low plant densities were associated with elevated immigration rates and greater propagule dispersal distances. Reproductive dominance among inside‐plot parents was higher for low‐density than for high‐density populations. Elevated local flower and fruit availability is probably leading to spatially more proximal bird foraging and propagule dispersal in areas with high density of reproductive plants. Nevertheless, genetic diversity, inbreeding coefficients and fine‐scale spatial genetic structure were similar across populations, despite differences in gene dispersal. This result may indicate that the opposing processes of longer dispersal events in low‐density populations vs. higher diversity of contributing parents in high‐density populations balance the resulting genetic outcomes and prevent genetic erosion in small populations and fragments.     

The Tomato Calcium Sensor Cbl10 and Its Interacting Protein Kinase Cipk6 Define a Signaling Pathway in Plant Immunity

Ca²⁺ signaling is an early and necessary event in plant immunity. The tomato (Solanum lycopersicum) kinase Pto triggers localized programmed cell death (PCD) upon recognition of Pseudomonas syringae effectors AvrPto or AvrPtoB. In a virus-induced gene silencing screen in Nicotiana benthamiana, we independently identified two components of a Ca²⁺-signaling system, Cbl10 (for calcineurin B-like protein) and Cipk6 (for calcineurin B-like interacting protein kinase), as their silencing inhibited Pto/AvrPto-elicited PCD. N. benthamiana Cbl10 and Cipk6 are also required for PCD triggered by other plant resistance genes and virus, oomycete, and nematode effectors and for host susceptibility to two P. syringae pathogens. Tomato Cipk6 interacts with Cbl10 and its in vitro kinase activity is enhanced in the presence of Cbl10 and Ca²⁺, suggesting that tomato Cbl10 and Cipk6 constitute a Ca²⁺-regulated signaling module. Overexpression of tomato Cipk6 in N. benthamiana leaves causes accumulation of reactive oxygen species (ROS), which requires the respiratory burst homolog RbohB. Tomato Cbl10 and Cipk6 interact with RbohB at the plasma membrane. Finally, Cbl10 and Cipk6 contribute to ROS generated during effector-triggered immunity in the interaction of P. syringae pv tomato DC3000 and N. benthamiana. We identify a role for the Cbl/Cipk signaling module in PCD, establishing a mechanistic link between Ca²⁺ and ROS signaling in plant immunity.     

The temperature dimension of the seed germination niche in fen wetlands

The seed germination niche partly determines adaptation, ecological breadth and geographic range in plant species. In temperate wetlands, environmental temperature is the chief regulator of germination timing, but the ecological significance of high and low temperatures during dormancy break and germination is still poorly understood. Our aim was to characterize the temperature dimension of the germination niche in mountain base-rich fens, determining (1) the effect of different temperatures on dormancy break and germination, and (2) whether different germination strategies may be identified at the species level. We conducted laboratory germination experiments with seeds of 15 species from these habitats, collected in 18 fen sites in the Cantabrian Mountains (Spain) for two consecutive years. In all the species, the seeds were totally or conditionally dormant at dispersal and stratification produced a significant increase of germination. In most cases, there was not an obligatory requirement for cold temperatures during dormancy break, since warm stratification promoted germination as well. Although the optimal germination thermoperiod was generally high (30/20 °C), most species could also germinate at lower temperatures after cold-stratification. We also identified a group of species associated to cold-water springs that germinated only at low temperatures. Our results demonstrate that dormancy break in mountain base-rich fens does not obligatorily depend on cold temperatures during overwintering. Furthermore, germination at cool temperatures may be more widespread in wetland habitats than previously thought. The existence of two distinctive germination strategies, ‘warm’ and ‘cool’, can potentially give rise to divergent species responses to climate change.     

An illustrated key to the soft-bottom caprellids (Crustacea: Amphipoda) of the Iberian Peninsula and remarks to their ecological distribution along the Andalusian coast

The soft-bottom caprellids of the Iberian Peninsula are revised. Nineteen species have been reported so far, 42 % being endemic to the Mediterranean Sea. The lateral view of all of them is provided, together with an illustrated key for all the species. An ecological study was also conducted during 2007–2010 along the Andalusian coast to explore the relationships of caprellids with abiotic data. A total of 90 stations (0–40 m deep) were sampled and 40 contained caprellids. Along the Atlantic, caprellids were present in only 20 % of the stations, while along the Mediterranean coast, caprellids were present in the 75 % of the sampling sites. Furthermore, the abundance of caprellids was also higher in the Mediterranean coast. The dominant species was Pseudolirius kroyeri (present in 24 stations and showing the highest abundances with 1,780 ind/m²), followed by Phtisica marina (22 stations) and Pariambus typicus (11 stations). According to CCA and BIO-ENV, sediment type, P, pH and oxygen were the parameters that better explained the distribution of caprellids. Although the three dominant species were found in all types of sediment, the univariate approach showed that P. kroyeri was significantly more abundant in fine sediments (silt–clay and very fine sands) than in gross sediments (coarse and very coarse sands). The majority of studies dealing with caprellids from the Iberian Peninsula have been focused on shallow waters and further efforts are needed to explore biodiversity of deeper areas.     

Biology and monitoring of Dryocosmus kuriphilus on Castanea sativa in Southern Italy

• 1 The cynipid gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) is an invasive wasp in Europe and is one of the major pests of chestnuts worldwide. An investigation of this cynipid was started in Campania, Southern Italy, in 2008, with the aim of providing guidelines for its sustainable control.
• 2 The number of larvae/gall increased in the second year of colonization relative to the first one but thereafter decreased in the third year of colonization, whereas the volume of the galls after the initial increase in the second year of colonization became stable. Adult emergence generally peaked between the middle of June and July.
• 3 The only reliable method for assessing the presence of the pest at its earliest stage was through dissecting the buds because oviposition scars on the buds tended to disappear during the winter.
• 4 Yellow traps were shown to be an effective method for assessing the emergence of cynipid adults and could potentially be used to time chemical applications in those cases in which this control method is feasible.
• 5 No correlation was recorded between the relative durations of the final stages (pupae, pharate adults and emergence).
• 6 Possible control strategies for this invasive pest are discussed.

     

Predicting genetic values: a kernel-based best linear unbiased prediction with genomic data

Genomic data provide a valuable source of information for modeling covariance structures, allowing a more accurate prediction of total genetic values (GVs). We apply the kriging concept, originally developed in the geostatistical context for predictions in the low-dimensional space, to the high-dimensional space spanned by genomic single nucleotide polymorphism (SNP) vectors and study its properties in different gene-action scenarios. Two different kriging methods ["universal kriging" (UK) and "simple kriging" (SK)] are presented. As a novelty, we suggest use of the family of Matérn covariance functions to model the covariance structure of SNP vectors. A genomic best linear unbiased prediction (GBLUP) is applied as a reference method. The three approaches are compared in a whole-genome simulation study considering additive, additive-dominance, and epistatic gene-action models. Predictive performance is measured in terms of correlation between true and predicted GVs and average true GVs of the individuals ranked best by prediction. We show that UK outperforms GBLUP in the presence of dominance and epistatic effects. In a limiting case, it is shown that the genomic covariance structure proposed by VanRaden (2008) can be considered as a covariance function with corresponding quadratic variogram. We also prove theoretically that if a specific linear relationship exists between covariance matrices for two linear mixed models, the GVs resulting from BLUP are linked by a scaling factor. Finally, the relation of kriging to other models is discussed and further options for modeling the covariance structure, which might be more appropriate in the genomic context, are suggested.     

Exploring the links between natural products and bacterial assemblages in the sponge Aplysina aerophoba

The sponge Aplysina aerophoba produces a large diversity of brominated alkaloids (BAs) and hosts a complex microbial assemblage. Although BAs are located within sponge cells, the enzymes that bind halogen elements to organic compounds have been exclusively described in algae, fungi, and bacteria. Bacterial communities within A. aerophoba could therefore be involved in the biosynthesis of these compounds. This study investigates whether changes in both the concentration of BAs and the bacterial assemblages are correlated in A. aerophoba. To do so, we quantified major natural products using high-performance liquid chromatography and analyzed bacterial assemblages using denaturing gradient gel electrophoresis on the 16S rRNA gene. We identified multiple associations between bacteria and natural products, including a strong relationship between a Chloroflexi phylotype and aplysinamisin-1 and between an unidentified bacterium and aerophobin-2 and isofistularin-3. Our results suggest that these bacteria could either be involved in the production of BAs or be directly affected by them. To our knowledge, this is one of the first reports that find a significant correlation between natural products and bacterial populations in any benthic organism. Further investigating these associations will shed light on the organization and functioning of host-endobiont systems such as Aplysina aerophoba.