6-Phosphofructo-2-kinase and D-fructose-2,6-bisphosphatase activities in mung bean seedlings

6-Phosphofructo-2-kinase (ATP: D-fructose-6-phosphate-2-phosphotransferase) and D-fructose-2,6-bisphosphatase activities have been found in extracts prepared from etiolated mung bean seedlings. The activity of 6-phosphofructo-2-kinase exhibits a sigmoidal shape in response to changes in concentrations of both substrates, D-fructose 6-phosphate and ATP (S_0.5 values of 1.8 and 1.2 mM, respectively). Inorganic orthophosphate (P_i) has a strong stimulating effect on the 2-kinase activity (A_0.5 at about 2 mM), moderately increasing the V_max and modifying the response into hyperbolic curves with K_m values of 0.4 and 0.2 mM for fructose 6-phosphate and ATP, respectively. 3-Phosphoglycerate (I_0.5 about 0.15 mM) partially inhibited the kinase activity by counteracting the P_i activation. In contrast, the activity of D-fructose-2,6-bisphosphatase (K_m 0.38 mM) is strongly inhibited by P_i (I_0.5 0.8 mM) lowering its affinity to fructose-2,6-P₂ (K_m 1.4 mM). 3-Phosphoglycerate activites the enzyme (A_0.5 at about 0.3 mM) without causing a significant change in its K_m for fructose-2,6-P₂. The activities of both of these enzymes in relationship to the metabolic role of D-fructose 2,6-bisphosphate in the germinating seed is discussed.     

Total Internal Reflection Accounts for the Bright Color of the Saharan Silver Ant

The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body.     

Adipose Tissue-Derived Stem Cells Reduce Acute and Chronic Kidney Damage in Mice

Acute and chronic kidney injuries (AKI and CKI) constitute syndromes responsible for a large part of renal failures, and are today still associated with high mortality rates. Given the lack of more effective therapies, there has been intense focus on the use stem cells for organ protective and regenerative effects. Mesenchymal stem cells (MSCs) have shown great potential in the treatment of various diseases of immune character, although there is still debate on its mechanism of action. Thus, for a greater understanding of the role of MSCs, we evaluated the effect of adipose tissue-derived stem cells (AdSCs) in an experimental model of nephrotoxicity induced by folic acid (FA) in FVB mice. AdSC-treated animals displayed kidney functional improvement 24h after therapy, represented by reduced serum urea after FA. These data correlated with cell cycle regulation and immune response modulation via reduced chemokine expression and reduced neutrophil infiltrate. Long-term analyses, 4 weeks after FA, indicated that AdSC treatment reduced kidney fibrosis and chronic inflammation. These were demonstrated by reduced interstitial collagen deposition and tissue chemokine and cytokine expression. Thus, we concluded that AdSC treatment played a protective role in the framework of nephrotoxic injury via modulation of inflammation and cell cycle regulation, resulting in reduced kidney damage and functional improvement, inhibiting organ fibrosis and providing long-term immune regulation.     

Kofyar cash-cropping: Choice and change in indigenous agricultural development

Amid discussions of an agricultural crisis and the failure of largescale, mechanized, capitalintensive development schemes in Nigeria, the Kofyar of Plateau State provide a case study of farmers spontaneously expanding food crop production for the market, using indigenous lowenergy technology. Temporary, followed by permanent, migration from the Jos Plateau homeland to frontier settlements on the fertile Benue plains has been accompanied by a change from initial shifting cultivation in forest clearings to permanent, intensively tilled and fertilized homestead fields. Labor is organized primarily in households that have grown in size and complexity. Cooperative and exchange work groups are also important for meeting seasonal bottlenecks and providing the careful, disciplined cultivation that intensive agriculture requires. Kofyar now devote up to 50% of their labor to cash crops, and they purchase considerable quantities of manufactured goods and medical services. Their uncoerced adaptation to an environment of new land resources and market incentives suggests both the advantages of indigenous development with a minimum of state control or interference and the limitations of a conventional dependency theory perspective.     

A simple device for controlled feeding of pasty materials used as fermentation substrates

Summary A simple device is described for con-trolled feeding of pasty materials in laboratory scale fed-batch cultures. The device was tested with apple pomace as raw material for production of microbial biomass, using the level of dissolved oxygen as controlled parameter.     

Genetic Analysis of Murine Arylsulfatase C and Steroid Sulfatase

SWR/J mice possess two- to threefold higher 4-methylumbelliferyl sulfate (4MUS), dehydroepiandrosterone sulfate (DHEAS) and estrone sulfate (E1S) sulfatase activities in liver and kidney extracts than do A/J mice. These interstrain activity differences are maintained throughout the 6- to 45-day postnatal period. Characteristics of the hepatic activities of SWR/J mice suggest that all three activities reside in the same enzyme. Biochemical properties of the SWR/J and A/J enzyme were not significantly different. Expression of hepatic enzyme activity is subject to regulation by an autosomal locus possessing two alleles with additive effects. Postnuclear E1S- and DHEAS-sulfatase activities are primarily microsomal. Although postnuclear hepatic 4MUS-sulfatase activity is predominantly microsomal, renal activity is primarily nonmicrosomal. Only that portion of 4MUS-sulfatase occurring in cell membranes appears capable of hydrolyzing E1S and DHEAS. The hepatic- and renal-specific subcellular distributions of 4MUS-sulfatase activity may reflect tissue differences in enzyme processing. Renal 4MUS-sulfatase activity is also controlled by an autosomal gene with two alleles having additive effects. Positive correlation between hepatic and renal 4MUS-sulfatase activities indicates that both activities are most likely influenced by the same gene.