Characteristics of rice straw and sewage sludge as composting materials in Valencia (Spain)

This work supports the idea that composting can be useful for minimizing the rice straw and sewage sludge environmental impact. Several physical, chemical and microbiological properties of these raw materials were analyzed. The characteristics of the rice straw were complementary to those of the sewage sludge for the application of composting. The C/N ratios suitable for a rapid increased in microbial activity were the lowest (17-24). A temperature of 62 degrees C during 48 h removed pathogenic microorganisms from rice straw and sewage sludge mixture. The results obtained in the present work suggested that these materials could be use in the composting process.     

Characterization of rhizobial isolates of Phaseolus vulgaris by staircase electrophoresis of low-molecular-weight RNA

Low-molecular-weight (LMW) RNA molecules were analyzed to characterize rhizobial isolates that nodulate the common bean growing in Spain. Since LMW RNA profiles, determined by staircase electrophoresis, varied across the rhizobial species nodulating beans, we demonstrated that bean isolates recovered from Spanish soils presumptively could be characterized as Rhizobium etli, Rhizobium gallicum, Rhizobium giardinii, Rhizobium leguminosarum bv. viciae and bv. trifolii, and Sinorhizobium fredii.     

Evaluation of plastic-composite supports in repeated fed-batch biofilm lactic acid fermentation by Lactobacillus casei

A customized stirred-tank biofilm reactor was designed for plastic-composite supports (PCS). In repeated-batch studies, the PCS-biofilm reactors outperformed the suspended-cell reactors by demonstrating higher lactic acid productivities (2.45 g l(-1) h(-1) vs 1.75 g l(-1) h(-1)) and greater glucose consumption rates (3.27 g l(-1) h(-1) vs 2.09 g l(-1) h(-1)). In the repeated fed-batch studies, reactors were spiked periodically with concentrated glucose (75%) to maintain a concentration of approximately 80 g of glucose l(-1) in the bioreactor. In suspended-cell fermentations with 10 g of yeast extract (YE) l(-1) and zero, one, two, and three glucose spikes, the lactic acid productivities were 2.64, 1.58, 0.80, and 0.62 g l(-1) h(-1), respectively. In comparison, biofilm reactors with 7 g of YE l(-1) and zero, one, two, and three glucose spikes achieved lactic acid productivities of 4.20, 2.78, 0.66, and 0.94 g l(-1) h(-1), respectively. The use of nystatin (30 U ml(-1)) subdued the contaminating yeast population with no effect on the lactic acid productivity of the biofilm reactors, but it did affect productivity in the suspended-cell bioreactor. Overall, in repeated fed-batch fermentations, the biofilm reactors consistently outperformed the suspended-cell bioreactors, required less YE, and produced up to 146 g of lactic acid l(-1) with 7 g of YE l(-1), whereas the suspended-cell reactor produced 132 g l(-1) with 10 g of YE l(-1).     

Functional properties of a truncated recombinant GIRK5 potassium channel

Xenopus laevis oocytes codify a G-protein-activated inward rectifier potassium channel (GIRK5 or Kir3.5). Coinjection of other GIRKs, the muscarinic m2 receptor, or Gbetagamma protein cRNAs is required to observe functional GIRKx-GIRK5 heteromultimers in oocytes. Studies with GIRK2 isoforms have shown that the size of the amino or carboxyl terminus plays a crucial role on giving functional K(+) channels. In this work we studied the properties of a GIRK5 with 25 amino acids deleted toward its amino-terminal domain. Injection of GIRK5-Delta25 cRNA alone displayed large basal and transient inward rectifying currents in oocytes. The instantaneous currents reached a stationary level after a long duration voltage pulse (10 s). For this relaxation, fast (tau(1)) and slow (tau(2)) time constants were estimated at different voltages. Recovery from inactivation followed a monoexponential function (tau=0.95+/-0.07 s). By contrast with other inward rectifier channels, blockade of GIRK5-Delta25 by extracellular Ba(2+) was voltage-independent (K(d)=102+/-2 microM), suggesting the presence of a Ba(2+) site at the external channel vestibule. To confirm this hypothesis, the Ba(2+) sensitivity of two charged mutants GIRK5-Delta25(N129E) and GIRK5-Delta25(K157E) at each of the external loops was determined. GIRK5-Delta25(N129E) and GIRK5-Delta25(K157E) showed a 100-fold and 2-fold higher affinity to Ba(2+), respectively, supporting the existence of this Ba(2+) binding site.     

The isthmic organizer signal FGF8 is required for cell survival in the prospective midbrain and cerebellum

Numerous studies have demonstrated that the midbrain and cerebellum develop from a region of the early neural tube comprising two distinct territories known as the mesencephalon (mes) and rostral metencephalon (met; rhombomere 1), respectively. Development of the mes and met is thought to be regulated by molecules produced by a signaling center, termed the isthmic organizer (IsO), which is localized at the boundary between them. FGF8 and WNT1 have been implicated as key components of IsO signaling activity, and previous studies have shown that in Wnt1(-/-) embryos, the mes/met is deleted by the 30 somite stage ( approximately E10) (McMahon, A. P. and Bradley, A. (1990) Cell 62, 1073-1085). We have studied the function of FGF8 in mouse mes/met development using a conditional gene inactivation approach. In our mutant embryos, Fgf8 expression was transiently detected, but then was eliminated in the mes/met by the 10 somite stage ( approximately E8.75). This resulted in a failure to maintain expression of Wnt1 as well as Fgf17, Fgf18, and Gbx2 in the mes/met at early somite stages, and in the absence of the midbrain and cerebellum at E17.5. We show that a major cause of the deletion of these structures is ectopic cell death in the mes/met between the 7 and 30 somite stages. Interestingly, we found that the prospective midbrain was deleted at an earlier stage than the prospective cerebellum. We observed a remarkably similar pattern of cell death in Wnt1 null homozygotes, and also detected ectopic mes/met cell death in En1 null homozygotes. Our data show that Fgf8 is part of a complex gene regulatory network that is essential for cell survival in the mes/met.     

Anterior neural plate regionalization in cripto null mutant mouse embryos in the absence of node and primitive streak

The relation between the role of the organizer at the gastrula stage and the activity of earlier signals in the specification, maintenance, and regionalization of the developing brain anlage is still controversial. Mouse embryos homozygous for null mutation in the cripto gene die at about 9.0 days postcoitum (d.p.c.) and fail to gastrulate and to form the node (the primary organizer). Here, we study the presence and the distribution of anterior neural plate molecular domains in cripto null mutants. We demonstrate that, in cripto(-/-) embryos, the main prosencephalic and mesencephalic regions are present and that they assume the correct topological organization. The identity of the anterior neural domains is maintained in mutant embryos at 8.5 d.p.c., as well as in mutant explants dissected at 8.5 d.p.c. and cultured in vitro for 24 h. Our data imply the existence of a stable neural regionalization of anterior character inside the cripto(-/-) embryos, despite the failure in both the gastrulation process and node formation. These results suggest that, in mouse embryos, the specification of the anterior neural identities can be maintained without an absolute requirement for the embryonic mesoderm and the node.     

Homocysteine is a potent inhibitor of human tumor cell gelatinases

Extracellular matrix-degrading gelatinases are mainly involved in tumor invasion and metastasis. Previous experimental data from our group and others suggested that homocysteine could have a potential modulatory role on the proteolytic balance at the extracellular matrix. Therefore, we studied the effects of homocysteine on extracellular matrix-degrading proteases using model human tumor cell lines and a combination of in vitro fluorogenic assay and zymographic techniques. Homocysteine is shown to be the thiol compound with the most potent inhibitory activity on matrix metalloproteinase 9. Zymographies reveal that matrix metalloproteinase 2 is, at least, as sensitive to inhibition by homocysteine as matrix metalloproteinase 9 is. This study opens new ways to the potential pharmacological use of thiol compounds.