Inhibitory effects of osteoprotegerin on osteoclast formation and function under serum-free conditions

The purpose of this study was to determine whether osteoprotegerin (OPG) could affect osteoclat differentiation and activation under serum-free conditions. Both duck embryo bone marrow cells and RAW264.7 cells were incubated with macrophage colony stimulatory factor (M-CSF) and receptor activator for nuclear factor kappaB ligand (RANKL) in serum-free medium to promote osteoclastogenesis. During cultivation, 0, 10, 20, 50, and 100 ng/mL OPG were added to various groups of cells. Osteoclast differentiation and activation were monitored via tartrate-resistant acid phosphatase (TRAP) staining, filamentous-actin rings analysis, and a bone resorption assay. Furthermore, the expression osteoclast-related genes, such as TRAP and receptor activator for nuclear factor kappaB (RANK), that was influenced by OPG in RAW264.7 cells was examined using real-time polymerase chain reaction. In summary, findings from the present study suggested that M-CSF with RANKL can promote osteoclast differentiation and activation, and enhance the expression of TRAP and RANK mRNA in osteoclasts. In contrast, OPG inhibited these activities under serum-free conditions.

Simvastatin inhibits osteoclast differentiation by scavenging reactive oxygen species

Osteoclasts, together with osteoblasts, control the amount of bone tissue and regulate bone remodeling. Osteoclast differentiation is an important factor related to the pathogenesis of bone-loss related diseases. Reactive oxygen species (ROS) acts as a signal mediator in osteoclast differentiation. Simvastatin, which inhibits 3-hydroxy-3-methylglutaryl coenzyme A, is a hypolipidemic drug which is known to affect bone metabolism and suppresses osteoclastogenesis induced by receptor activator of nuclear factor-kappaB ligand (RANKL). In this study, we analyzed whether simvastatin can inhibit RANKL-induced osteoclastogenesis through suppression of the subsequently formed ROS and investigated whether simvastatin can inhibit H2O2-induced signaling pathways in osteoclast differentiation. We found that simvastatin decreased expression of tartrate-resistant acid phosphatase (TRAP), a genetic marker of osteoclast differentiation, and inhibited intracellular ROS generation in RAW 264.7 cell lines. ROS generation activated NF-kappaB, protein kinases B (AKT), mitogen-activated protein kinases signaling pathways such as c-JUN N-terminal kinases, p38 MAP kinases as well as extracellular signal-regulated kinase. Simvastatin was found to suppress these H2O2-induced signaling pathways in osteoclastogenesis. Together, these results indicate that simvastatin acts as an osteoclastogenesis inhibitor through suppression of ROS-mediated signaling pathways. This indicates that simvastatin has potential usefulness for osteoporosis and pathological bone resorption.

Isoenzymatic polymorphism in the leaf-cutting ant Atta capiguara Gonçalves (hymenoptera: formicidae)

This study was carried out to analyze the genetic population structure of Atta capiguara from 12 nests collected in Tapejara in the state of Paraná, Brazil, using isoenzyme polymorphisms. The analyzed isoenzymes were esterases (EST - EC 3.1.1.1), acid phosphatase (ACP - EC 3.1.3.2) and carbonic anhydrase (CA - EC 4.2.1.1). Ten loci were found in A.capiguara and four polymorphic loci were detected. The observed heterozigosity (0.0296) was low when compared to the expected heterozigosity (0.1461). The high value of F IS (0.7954) shows an excess of homozygous genotypes probably caused by inbreeding.

Epigenetics of dominance for enzyme activity.

We have isolated and purified two parental homodimers and a unique heterodimer of acid phosphatase [coded by Acph-1 (1.05)(F) and Acph-1 (0.95)(S)] from isogenic homozygotes and heterozygotes of Drosophila malerkotliana. F and S produce qualitatively different allozymes and the two alleles are expressed equally within and across all three genotypes and F and S play an equal role in the epigenetics of dominance. Subunit interaction in the heterodimer over a wide range of H+ concentrations accounts for the epigenetics of dominance for enzyme activity.

Acid phosphatase polymorphism within and among populations of Cauliflower (Brassica oleracea var botrytis)

Eighty-one lines of cauliflower (Brassica oleracea var. botrytis) from 12 populations used to produce commercial hybrids in Brazil were screened for polymorphism in the acid phosphatase system, in order to evaluate the usefulness of this marker for the determination of the parental contamination level in hybrid seeds. Little polymorphism was detected in the examined lines, but the system appeared to be very useful for hybrid identification, since the only condition required was polymorphism between the two parental lines. If the analyzed lines were used for hybrid production, 8.4 percent and 12.3 percent of the possible crosses would result in hybrids which can be positively identified using the APS-1 and B1 loci, respectively. If only one plant of each homozygous type (SS or FF) was analyzed in each population, 41 percent and 50 percent of the possible crosses would result in hybrids which can be positively identified using the APS-1 and B1 loci, respectively

Distinguishing clonal apple rootstocks by isozymes banding patterns.

Molecular characterisation of clonal apple rootstocks using isozymes was carried out to identify isozyme polymorphism in seven clonal apple rootstocks and to identify the most characteristic and stable enzyme markers for each individual rootstock. Five enzyme systems were studied out of which polyphenol oxidase, malate dehydrogenase, acid phosphatase and peroxidase were useful in discriminating among the rootstocks. The peroxidase enzyme system showed maximum variation and esterase showed the least variation among the rootstocks. Out of seven rootstocks, three were distinguished on the basis of one enzyme system only (M.3 with MDH or PER, M.7 with PPO or PER and MM. 111 with MDH). Out of the sixteen loci studied seven were found to be polymorphic. Genetic variation among the rootstocks was explained on the basis of various parameters. The percentage of polymorphic loci varied from 13.33 to 35.71 per cent.

Allozyme variation among six populations of the freshwater-snail Oncomelania hupensis in Zhejiang, China.

Thirteen enzymes encoded by 16 loci of six population of Oncomelania hupensis in Zhejiang, China, were investigated by means of starch gel electrophoresis. Ten loci (AO, 6PGD, ME, AKP, OCT-1, HBDH-1, HBDH-2, XDH, MDH and MPI) were monomorphic and 6 loci (OCT-2, PGI, AAT, PGM-1, PGM-2 and ACP) were polymorphic. Three enzymes (OCT, HBDH and PGM) were encoded by 2 loci. The results indicated that there were allozyme variations in two subspecies, O.h. hupensis and O.h. fausti in Zhejiang, China. Nei's multilocus genetic distances (D) between subspecies ranged from 0.167 to 0.265. Minor genetic distances were detected between populations of the same subspecies. The results indicated that the enzyme acid phosphatase (ACP) is a possible marker to measure the degree of susceptibility of O. hupensis to S. Japonicum.

Effect of carbon source and extracellular pH on the acidification of the culture medium and phosphatase excretion in Neurospora crassa

Exogenous Ca2+ at concentrations up to 3.5 mM increases the sucrose-induced acidification of the culture medium when the mold Neurospora crassa is grown on low-phosphate (Pi) medium at pH 7.8. Induction depends on the pH of the culture medium adjusted for conidial inoculation and on the absence of carbon sources generating cytoplasmic acetyl CoA. Furthermore, the excretion of Pi-repressible acid and alkaline phosphatases was not stimulated by increasing exogenous Ca2+ levels. We also provide evidence that the extracellular pH monitoring by Neurospora crassa may be a determinant in the selective excretion of Pi-repressible acid and alkaline phosphatases.