Reproductive ecology of the female pink cusk-eel (Genypterus blacodes): evaluating differences between fishery management zones in the Chilean austral zone

The pink cusk-eel (Genypterus blacodes), a benthic-demersal fish confined to the southern hemisphere, supports an important commercial fishery in Chile where it is exploited over an extensive geographic area. Although the fishery was originally divided into a northern (41º28′–47º00′S) and southern (47º00′–57º00′S) zone for the purposes of fisheries management, recent studies have reported significant differences in life history parameters between these zones. Individuals from the southern zone reached larger asymptotic sizes and possessed higher survival rates compared to the northern zone. We estimate and compare the gonadosomatic index (GSI), shape of the maturity ogive, and length at 50 % maturity (L _50%) of female G. blacodes between management zones and across time using biological data collected from the industrial fleet between 1985 and 2009. Females in the northern zone had higher monthly mean GSI than females in the southern zone. Our analyses also revealed L _50% to be significantly higher in the southern zone than in the northern zone from 1985 to 2009. The significant differences in life-history traits between fishery management zones agree with the trade-offs predicted by Charnov’s life history theory. Together these results provide additional support for the hypothesis that two separate stocks exist and suggest that females from the northern zone have developed a life-history strategy, which favours early maturation and a proportionally greater investment in reproduction than females from the southern zone.     

Precise control of miR-125b levels is required to create a regeneration-permissive environment after spinal cord injury: a cross-species comparison between salamander and rat

Most spinal cord injuries lead to permanent paralysis in mammals. By contrast, the remarkable regenerative abilities of salamanders enable full functional recovery even from complete spinal cord transections. The molecular differences underlying this evolutionary divergence between mammals and amphibians are poorly understood. We focused on upstream regulators of gene expression as primary entry points into this question. We identified a group of microRNAs (miRNAs) that are conserved between the Mexican axolotl salamander (Ambystoma mexicanum) and mammals but show marked cross-species differences in regulation patterns following spinal cord injury. We found that precise post-injury levels of one of these miRNAs (miR-125b) is essential for functional recovery, and guides correct regeneration of axons through the lesion site in a process involving the direct downstream target Sema4D in axolotls. Translating these results to a mammalian model, we increased miR-125b levels in the rat through mimic treatments following spinal cord transection. These treatments downregulated Sema4D and other glial-scar-related genes, and enhanced the animal’s functional recovery. Our study identifies a key regulatory molecule conserved between salamander and mammal, and shows that the expression of miR-125b and Sema4D must be carefully controlled in the right cells at the correct level to promote regeneration. We also show that these molecular components of the salamander’s regeneration-permissive environment can be experimentally harnessed to improve treatment outcomes for mammalian spinal cord injuries.KEY WORDS: Regeneration, Axolotl, Spinal cord injury, microRNAs     

Preparation of a respiratory syncytial virus human reference serum for use in the quantitation of neutralization antibody.

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection in infants, young children and the elderly. Yet, the development of a vaccine to protect against RSV infection still remains an unmet need. At present, immune responses to experimental vaccines under investigation are usually evaluated by ELISA and/or by neutralization assays against RSV. However, both types of assays are generally performed somewhat differently at different laboratories. An important step towards standardization of serology is the use of a standard human reference serum enabling normalization of results generated within and between laboratories. To fill this need, we prepared and characterized a human reference serum against the A2 strain of respiratory syncytial virus. The serum represents a pool of more than 400 individual human sera obtained from commercial sources. The sera were screened and selected on the basis of individual RSV neutralization titers. A final neutralization titer of 973 (95% C.I., 884-1072) was assigned to the final reference serum pool after it was tested three times in the presence of 10% guinea pig complement and a titer of 286 (95% C.I., 243-337) was assigned to the serum when it was tested in the absence of an exogenous complement source. Sterilely reconstituted lyophilized aliquots of the serum exhibited a stable neutralization titer for at least 1 month at room temperature and at 4 degrees C, as well as after 5 weekly freeze-and-thaw cycles at -20 degrees C. In the lyophilized state, the neutralization titer of the lyophilized reagent was stable for at least 6 months, the last time point tested. Two additional smaller pools of serum with high and medium neutralization titers of 2692 and 575, respectively, were also produced in parallel for use as positive controls and were designated as control sera. The reference serum can be used to normalize neutralization and/or other RSV-specific assay results from different laboratories and the control sera can be used for quality control purposes or as part of a panel to test operator proficiency. Individual lyophilized aliquots of the reference and control sera may be obtained from the US National Institute of Allergy and Infectious Diseases (NIAID) Reference Reagent Repository.     

The molecular chaperone Hsc70 interacts with the vesicular monoamine transporter-2

Synaptic transmission depends on the efficient loading of transmitters into synaptic vesicles by vesicular neurotransmitter transporters. The vesicular monoamine transporter-2 (VMAT2) is essential for loading monoamines into vesicles and maintaining normal neurotransmission. In an effort to understand the regulatory mechanisms associated with VMAT2, we have embarked upon a systematic search for interacting proteins. Glutathione-S-transferase pull-down assays combined with mass spectrometry led to the identification of the 70-kDa heat shock cognate protein (Hsc70) as a VMAT2 interacting protein. Co-immunoprecipitation experiments in brain tissue and heterologous cells confirmed this interaction. A direct binding was observed between the amino terminus and the third cytoplasmic loop of VMAT2, as well as, a region containing the substrate binding and the carboxy-terminal domains of Hsc70. Furthermore, VMAT2 and Hsc70 co-fractionated with purified synaptic vesicles obtained from a sucrose gradient, suggesting that this interaction occurs at the synaptic vesicle membrane. The functional significance of this novel VMAT2/Hsc70 interaction was examined by performing vesicular uptake assays in heterologous cells and purified synaptic vesicles from brain tissue. Recombinant Hsc70 produced a dose-dependent inhibition of VMAT2 activity. This effect was mimicked by the closely related Hsp70 protein. In contrast, VMAT2 activity was not altered in the presence of previously denatured Hsc70 or Hsp70, as well as the unrelated Hsp60 protein; confirming the specificity of the Hsc70 effect. Finally, a purified Hsc70 fragment that binds VMAT2 was sufficient to inhibit VMAT2 activity in synaptic vesicles. Our results suggest an important role for Hsc70 in VMAT2 function and regulation.     

Venezuelan Equine Encephalitis in Panama: Fatal Endemic Disease and Genetic Diversity of Etiologic Viral Strains

Venezuelan equine encephalitis (VEE) is a reemerging, mosquito-borne viral disease of the neotropics that is severely debilitating and sometimes fatal to humans. Periodic epidemics mediated by equine amplification have been recognized since the 1920s, but interepidemic disease is rarely recognized. We report here clinical findings and genetic characterization of 42 cases of endemic VEE detected in Panama from 1961–2004. Recent clusters of cases occurred in Darien (eastern Panama) and Panama provinces (central Panama) near rainforest and swamp habitats. Patients ranged from 10 months to 48 years of age, and the more severe cases with neurological complications, including one fatal infection, were observed in children. The VEE virus strains isolated from these cases all belonged to an enzootic, subtype ID lineage known to circulate among sylvatic vectors and rodent reservoir hosts in Panama and Peru. These findings underscore endemic VEE as an important but usually neglected arboviral disease of Latin America.     

Relative Precision of Inhaler Aerodynamic Particle Size Distribution (APSD) Metrics by Full Resolution and Abbreviated Andersen Cascade Impactors (ACIs): Part 1

The purpose of this study was to compare relative precision of two different abbreviated impactor measurement (AIM) systems and a traditional multi-stage cascade impactor (CI). The experimental design was chosen to provide separate estimates of variability for each impactor type. Full-resolution CIs are useful for characterizing the aerosol aerodynamic particle size distribution of orally inhaled products during development but are too cumbersome, time-consuming, and resource-intensive for other applications, such as routine quality control (QC). This article presents a proof-of-concept experiment, where two AIM systems configured to provide metrics pertinent to QC (QC-system) and human respiratory tract (HRT-system) were evaluated using a hydrofluoroalkane-albuterol pressurized metered dose inhaler. The Andersen eight-stage CI (ACI) served as the benchmark apparatus. The statistical design allowed estimation of precision with each CI configuration. Apart from one source of systematic error affecting extra-fine particle fraction from the HRT-system, no other bias was detected with either abbreviated system. The observed bias was shown to be caused by particle bounce following the displacement of surfactant by the shear force of the airflow diverging above the collection plate of the second impaction stage. A procedure was subsequently developed that eliminated this source of error, as described in the second article of this series (submitted to AAPS PharmSciTech). Measurements obtained with both abbreviated impactors were very similar in precision to the ACI for all measures of in vitro performance evaluated. Such abbreviated impactors can therefore be substituted for the ACI in certain situations, such as inhaler QC or add-on device testing.     

ABI2-deficient mice exhibit defective cell migration, aberrant dendritic spine morphogenesis, and deficits in learning and memory

The Abl-interactor (Abi) family of adaptor proteins has been linked to signaling pathways involving the Abl tyrosine kinases and the Rac GTPase. Abi proteins localize to sites of actin polymerization in protrusive membrane structures and regulate actin dynamics in vitro. Here we demonstrate that Abi2 modulates cell morphogenesis and migration in vivo. Homozygous deletion of murine abi2 produced abnormal phenotypes in the eye and brain, the tissues with the highest Abi2 expression. In the absence of Abi2, secondary lens fiber orientation and migration were defective in the eye, without detectable defects in proliferation, differentiation, or apoptosis. These phenotypes were consistent with the localization of Abi2 at adherens junctions in the developing lens and at nascent epithelial cell adherens junctions in vitro. Downregulation of Abi expression by RNA interference impaired adherens junction formation and correlated with downregulation of the Wave actin-nucleation promoting factor. Loss of Abi2 also resulted in cell migration defects in the neocortex and hippocampus, abnormal dendritic spine morphology and density, and severe deficits in short- and long-term memory. These findings support a role for Abi2 in the regulation of cytoskeletal dynamics at adherens junctions and dendritic spines, which is critical for intercellular connectivity, cell morphogenesis, and cognitive functions.     

Optimization of a protocol for direct organogenesis of red clover (Trifolium pratense L.) meristems for breeding purposes

A series of experiments were carried out in order to optimize a protocol for the direct organogenesis of Chilean red clover germplasm. A range of cultivars were used to analyze the effect of explant source (crown or stem meristems of vegetative plants), culture media and plant growth regulators. Our findings showed that stem meristems were easier to obtain, presented lower levels of contamination and a better development than crown meristems. The L2 medium showed better results than B5 and MS media for the cultivars and experimental lines studied. L2 medium supplemented with 0.003 mg/l of 4-amino-3,5,6-trichloropicolinic acid and 1.0 mg/l of 6-benzylaminopurine gave consistently better results and will be applied in our breeding program to propagate, maintain and eliminate viruses from elite red clover clones.     

Molecular effects of lithium

Bipolar affective disorder is a common, severe, chronic, and often life-threatening illness, associated with other medical and psychiatric conditions (i.e., co-morbidity). The treatment of this devastating disorder was revolutionized by the discovery of lithium's antimanic effects over fifty years ago. Recent molecular and cellular biological studies have identified a number of unexpected targets for this monovalent cation, notably glycogen synthase kinase-3 and neurotrophic signaling cascades. These findings are leading to a reconceptualization of the biological underpinnings of bipolar disorder and are resulting in considerable interest in utilizing lithium for the treatment of certain neurodegenerative disorders. We review recent insights into lithium's actions including its direct inhibitory actions on inositol monophosphatase, inositol polyphosphate 1-phosphatase, glycogen synthase kinase-3, fructose 1,6-bisphosphatase, bisphosphate nucleotidase, and phosphoglucomutase enzymes. We also discuss lithium's intracellular downstream targets including adenylate cyclase, the phosphoinositol cascade (and its effect on protein kinase C), arachidonic acid metabolism, and effects on neurotrophic cascades. Many of the new insights of lithium's actions may lead to the strategic development of improved therapeutics for the treatment of bipolar disorder.     

Plant genomics: an overview

Recent technological advancements have substantially expanded our ability to analyze and understand plant genomes and to reduce the gap existing between genotype and phenotype. The fast evolving field of genomics allows scientists to analyze thousand of genes in parallel, to understand the genetic architecture of plant genomes and also to isolate the genes responsible for mutations. Furthermore, whole genomes can now be sequenced. This review addresses these issues and also discusses ways to extract biological meaning from DNA data. Although genomic issuesare addressed from a plant perspective, this review provides insights into the genomic analyses of other organisms.