Preferential Targeting of Nav1.6 Voltage-Gated Na+ Channels to the Axon Initial Segment during Development

During axonal maturation, voltage-gated sodium (Na_v) channels accumulate at the axon initial segment (AIS) at high concentrations. This localization is necessary for the efficient initiation of action potentials. The mechanisms underlying channel trafficking to the AIS during axonal development have remained elusive due to a lack of Na_v reagents suitable for high resolution imaging of channels located specifically on the cell surface. Using an optical pulse-chase approach in combination with a novel Na_v1.6 construct containing an extracellular biotinylation domain we demonstrate that Na_v1.6 channels are preferentially inserted into the AIS membrane during neuronal development via direct vesicular trafficking. Single-molecule tracking illustrates that axonal channels are immediately immobilized following delivery, while channels delivered to the soma are often mobile. Neither a Na_v1.6 channel lacking the ankyrin-binding motif nor a chimeric K_v2.1 channel containing the Na_v ankyrinG-binding domain show preferential AIS insertion. Together these data support a model where ankyrinG-binding is required for preferential Na_v1.6 insertion into the AIS plasma membrane. In contrast, ankyrinG-binding alone does not confer the preferential delivery of proteins to the AIS.     

Trisomy 8, a Cytogenetic Abnormality in Myelodysplastic Syndromes,Is Constitutional or Not?

Isolated trisomy 8 is not considered presumptive evidence of myelodysplastic syndrome (MDS) in cases without minimal morphological criteria. One reason given is that trisomy 8 (+8) can be found as a constitutional mosaicism (cT8M). We tried to clarify the incidence of cT8M in myeloid neoplasms, specifically in MDS, and the diagnostic value of isolated +8 in MDS. Twenty-two MDS and 10 other myeloid neoplasms carrying +8 were studied. Trisomy 8 was determined in peripheral blood by conventional cytogenetics (CC) and on granulocytes, CD3+ lymphocytes and oral mucosa cells by fluorescence in situ hybridization (FISH). In peripheral blood CC, +8 was seen in 4/32 patients. By FISH, only one patient with chronic myelomonocytic leukemia showed +8 in all cell samples and was interpreted as a cT8M. In our series +8 was acquired in all MDS. Probably, once discarded cT8M by FISH from CD3+ lymphocytes and non-hematological cells, +8 should be considered with enough evidence to MDS.     

Development of sucrose-utilizing Escherichia coli K-12 strain by cloning β-fructofuranosidases and its application for l-threonine production

Sucrose is one of the most promising carbon sources for industrial fermentation. To achieve sucrose catabolism, the sucrose utilization operons have been introduced into microorganisms that are not able to utilize sucrose. However, the rates of growth and sucrose uptake of these engineered strains were relatively low to be successfully employed for industrial applications. Here, we report a practical example of developing sucrose-utilizing microorganisms using Escherichia coli K-12 as a model system. The sucrose utilizing ability was acquired by introducing only β-fructofuranosidase from three different sucrose-utilizing organisms (Mannheimia succiniciproducens, E. coli W, and Bacillus subtilis). Among them, the M. succiniciproducens β-fructofuranosidase was found to be the most effective for sucrose utilization. Analyses of the underlying mechanism revealed that sucrose was hydrolyzed into glucose and fructose in the extracellular space and both liberated hexoses could be transported by their respective uptake systems in E. coli K-12. To prove that this system can also be applied for the production of useful metabolites, the M. succiniciproducens β-fructofuranosidase was introduced into the engineered l-threonine production strain of E. coli K-12. This recombinant strain was able to produce 51.1 g/L l-threonine by fed-batch culture, resulting in an overall yield of 0.284 g l-threonine per g sucrose. This simple approach to make E. coli K-12 to acquire sucrose-utilizing ability and its successful biotechnological application can be employed to develop sustainable bioprocesses using renewable biomass.     

Performance of staged and non-staged up-flow anaerobic sludge bed (USSB and UASB) reactors treating low strength complex wastewater

The use of anaerobic processes to treat low-strength wastewater has been increasing in recent years due to their favourable performance-costs balance. For optimal results, it is necessary to identify reactor configurations that are best suited for this kind of application. This paper reports on the comparative study carried out with two high-rate anaerobic reactor systems with the objective of evaluating their performances when used for the treatment of low-strength, complex wastewater. One of the systems is the commonly used up-flow anaerobic sludge blanket (UASB) reactor. The other is the up-flow staged sludge bed (USSB) system in which the reactor was divided longitudinally into 3, 5 and 7 compartments by the use of baffles. The reactors (9 l) were fed with a synthetic, soluble and colloidal waste (chemical oxygen demand (COD) < 1000 mg/l) and operated at 28°C and 24 h hydraulic retention time. Intermediate flow hydraulics, between plug-flow and completely-mixed, in the UASB and 7 stages USSB reactors allowed efficient degradation of substrates with minimum effluent concentrations. Low number of compartments in the USSB reactors increased the levels of short-circuiting thus reducing substrate removal efficiencies. All reactors showed high COD removal efficiencies (93–98%) and thus can be regarded as suitable for the treatment of low strength, complex wastewater. Staged anaerobic reactors can be a good alternative for this kind of application provided they are fitted with a large enough (≥7) number of compartments to fully take advantage of their strengths. Scale factors seem to have influenced importantly on the comparison between one and multi staged sludge-bed reactors and, therefore, observations made here could change at larger reactor volumes.     

Floral sesquiterpenes and their synthesis in dioecious kiwifruit

Kiwifruit species are vigorously growing dioecious vines that rely on bees and other insects for pollen transfer between spatially separated male and female individuals. Floral volatile terpene cues for insect pollinator attraction were characterized from flowers of the most widely grown and economically important kiwifruit cultivar Actinidia deliciosa ‘Hayward’ and its male pollinator ‘Chieftain’. The sesquiterpenes α-farnesene and germacrene D dominated in all floral tissues and the emission of these compounds was detected throughout the day, with lower levels at night. Two terpene synthase (TPS) genes were isolated from A. deliciosa petals that produced (+)-germacrene D and (E,E)-α-farnesene respectively. Both TPS genes were expressed in the same tissues and at the same times as their corresponding floral volatiles. Here we discuss these results with respect to plant and insect ecology and the evolution and structure of sesquiterpene synthases.Key words: terpene, dioecy, kiwifruit, volatile, ecology, evolution, flower     

Seguridad de los análogos de insulina: qué evaluar,cómo hacerlo y cómo interpretar los resultados

The widespread use of insulin analogues is based not only on the pharmacokinetics of these preparations, which is much closer to the physiology of insulin secretion under normal conditions, but also on their safety and effectiveness. The publication of a possible association between the use of a long-acting insulin analogue (glargine) and breast cancer has caused uneasiness among the medical community regarding the safety of these analogues.The mechanism of increased tumor activity of insulin analogues is explained by the fact that they act through insulin receptors (IR) and insulin-like growth factor-1 (IGF-1R), stimulating cell growth and inhibiting apoptosis. There are two major mechanisms: an increase in the binding time of insulin to IR and increased activation of IGF-1R. Therefore, to evaluate the safety of an analogue, the slower dissociation rate from its insulin receptor must be excluded, as well as the increased affinity for the IGF-1 receptor. This is equivalent to an index of mitogenic/metabolic activity of less than 1. These aspects can only be evaluated through study of cell lines and animal testing, which are reductionist models that cannot always be extrapolated to humans. To date, there are no data to question the safety of insulin analogues in general. However, the results of observational studies and some in vitro studies, suggesting a potential risk of mitogenicity with the administration of glargine, have caused some alarm among the medical community. Until now, there are no data to refute or confirm this risk and, therefore, evaluation of the existing data is crucial to obtain objective information.     

A new species of Pliopithecus Gervais, 1849 (Primates: Pliopithecidae) from the Middle Miocene (MN8) of Abocador de Can Mata (els Hostalets de Pierola,Catalonia, Spain)

Pliopithecus (Pliopithecus) canmatensis sp. nov. is described from several Late Aragonian localities from Abocador de Can Mata (ACM) in els Hostalets de Pierola (Vallès‐Penedès Basin, Catalonia, Spain), spanning from ～11.7 to 11.6 Ma (C5r.3r subchron), and being correlated to the MN8 (reference locality La Grive L3). The ACM remains display a pliopithecine dental morphology with well‐developed pliopithecine triangles on M/2 and M/3. This, together with other occlusal details, negates an attribution to the subgenus Epipliopithecus. Although slightly smaller, the ACM remains are most similar in size to comparable elements of P. piveteaui and P. antiquus. Several occlusal details (such as the greater development of the buccal cingulid in lower molars) and dental proportions (M/3 much longer than M/2), however, indicate greater similarities with P. antiquus from Sansan and La Grive. The ACM remains, however, differ from P. antiquus in dental proportions as well as occlusal morphology of the lower molars (including the less peripheral position of the protoconid and more medial position of the hypoconulid, the more mesial position of the buccal cuspids as compared to the lingual ones, the narrower but distinct mesial fovea, the higher trigonid, and the more extensive buccal cingulid, among others). These differences justify a taxonomic distinction at the species level of the ACM pliopithecid remains with respect to P. antiquus. Previous pliopithecid findings from the Vallès‐Penedès Basin, previously attributed to P. antiquus, are neither attributable to the latter species nor to the newly erected one. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

The benthic fauna of Sabancuy Estuary, Campeche, Mexico]

The fish and invertebrates community structure in the Sabancuy estuary was analyzed in two seasons and 14 sampling stations (13 along the estuary and one in the marine adjacent coast). No significant differences were found between seasons. The environmental frame defines two zones within the estuary, the first extends from the access highway to Sabancuy town until the Pujo mouth in the west; the second from the bridge to the estuary head in the east. The most abundant invertebrates were mollusks (51.8% of the total), in biomass the crustaceans dominated. The fish included 21 families and 33 species; the most abundant were Gerridae, Scianidae, Sparidae, Lutjanidae and Ciprinodontidae. The highest diversities of both communities correspond to the central part of the estuary. These communities include three sections with notable differences in faunal distribution: one is influenced by the exit to Terminos lagoon, the secondary in the estuary head and a third is in a transition zone defined by the proximity of the town access bridge. The ecological organization suggests a strong division caused by the bridge, both sides are scarce in habitats and nutrient resources and this is reflected in the low species counts.     

Daily cycle and body characteristics of mating Litopenaeus vannamei shrimps (Decapoda: Penaeidae) in the wild off southern Sinaloa, Mexico

Mating behavior has been described for very few species of penaeoid shrimps. We describe some of the environmental conditions under which mating of Litopenaeus vannamei took place in the ocean, as inferred by the presence of attached spermatophores on the thelycum of females, combined with the presence of mature males with empty ampulla terminalis, both evidence of recent copulation. Out of a total of twelve 24 hr samplings on board the research vessel B/O "EL PUMA", one was selected to examine mating. There were four periods of observation. The highest frequency of females with attached spermatophores were found during the daytime whilst the lowest was registered during the night. Females with attached spermatophore were mostly at stages IV and V of ovarian maturity and fell within the 30-50 mm of C.L. range. Copulating male size ranged between 30 and 40 mm of C.L. and there was a close relation between the percentage of mating females and males. Male to female ratio varied throughout the sampling period but it was never 1:1. The female mean size was, in all cases, bigger than the male mean size. Among the environmental factors, salinity and oxygen varied very slightly throughout the sampling period; temperature variation was more pronounced and those changes were attributed to the tidal oscillation.