Influence of complex nutrient source on growth of and curvacin a production by sausage isolate Lactobacillus curvatus LTH 1174

Lactobacillus curvatus LTH 1174, a fermented sausage isolate, produces the antilisterial bacteriocin curvacin A. Its biokinetics of cell growth and bacteriocin production as a function of various concentrations of a complex nutrient source were investigated in vitro during laboratory fermentations with modified MRS medium. A modification of the nutrient depletion model was used to fit the data describing growth and bacteriocin production. Both cell growth and bacteriocin activity were influenced by changes in the complex nutrient source concentration. Standard MRS medium clearly limited the growth of L. curvatus LTH 1174. Higher nutrient concentrations, up to a certain degree, led to improved growth, a higher attainable biomass concentration, and a higher bacteriocin activity in the supernatant. A lower concentration of complex nutrient source caused severe growth inhibition, leading to a lower biomass concentration but a much higher specific bacteriocin production. When examining the separate components of the complex nutrient source, a stimulating effect of bacteriological peptone on growth was found without an adverse effect on bacteriocin production, resulting in increased curvacin A activity. Furthermore, specific depletion of the amino acids tyrosine, serine, and asparagine/aspartic acid was observed for this strain.     

Necrotizing fasciitis in an immunocompetent patient caused by Apophysomyces elegans

A case study is presented of a 7-year-old boy, seriously injured in a car accident, who developed a fatal infection due to Aphophysomyces elegans--a mold of the Mucoracea family. Fungal invasion was initially manifested by a spotted wound in the left lumbar region which developed into a necrotizing fasciitis. Later this progressed to the right lumbar area, including the gluteus and the corresponding flank. Antimycotic treatment proved ineffective, and the child died 8 weeks after the accident. Other cases due to this fungus are reviewed.     

Structure of gene coding for the fruit body-specific hydrophobin Fbh1 of the edible basidiomycete Pleurotus ostreatus

Two fruit body-specific hydrophobins (Fbh1 and POH1) have been identified in two different strains of the edible basidiomycete Pleurotus ostreatus. Comparison of their nucleotide and amino acid sequences yielded similarity values (59% and 66%, respectively) smaller than those found for alleles of the same hydrophobin gene but higher than those found for different hydrophobin genes in P. ostreatus var. florida (Pe?as et al 2002). In this paper, we have addressed the question of Fbh1 and POH1 allelism by studying the structure of the gene fbh1 and by a classical genetic analysis to compare it with that of POH1. The structure of both genes is similar, as revealed by the similarity of their promoters and leader peptide sequences and by the conserved position of their introns. Furthermore, the allelism analysis revealed that both genes segregated as alleles when present in the same hybrid. These results suggest an allelic condition for POH1 and fbh1 and stress the importance of the similarity of fbh1/POH1 promoter and leader sequences. Furthermore, we have identified various microsatellite-like regions in this gene that can be used for strain and species typing in the future.     

LC/MS/NMR analysis of isomeric divanilloylquinic acids from the root bark of Fagara zanthoxyloides Lam

Gradient HPLC coupled to DAD/UV, MS/MS and NMR has been applied to the rapid structure determination of three new isomeric divanilloylquinic acids from Fagara zanthoxyloides collected in Burkina Faso: 3,4-O-divanilloylquinic acid, 3,5-O-divanilloylquinic acid and 4,5-O-divanilloylquinic acid. Furthermore these new compounds named burkinabins A-C could play a useful role in sickle cell disease, as the active agents of Fagara zanthoxylo?des are said to be unidentified aromatic compounds with carboxylic acid grouping (Adesanya, S.A., Sofowora, A., 1983. Biological standardisation of Zanthoxylum roots for antisickling activity. Planta Med. 48, 27-33).     

Mice lacking ZFHX1B,the gene that codes for Smad-interacting protein-1, reveal a role for multiple neural crest cell defects in the etiology of Hirschsprung disease-mental retardation syndrome

Recently, mutations in ZFHX1B, the gene that encodes Smad-interacting protein-1 (SIP1), were found to be implicated in the etiology of a dominant form of Hirschsprung disease-mental retardation syndrome in humans. To clarify the molecular mechanisms underlying the clinical features of SIP1 deficiency, we generated mice that bear a mutation comparable to those found in several human patients. Here, we show that Zfhx1b-knockout mice do not develop postotic vagal neural crest cells, the precursors of the enteric nervous system that is affected in patients with Hirschsprung disease, and they display a delamination arrest of cranial neural crest cells, which form the skeletomuscular elements of the vertebrate head. This suggests that Sip1 is essential for the development of vagal neural crest precursors and the migratory behavior of cranial neural crest in the mouse. Furthermore, we show that Sip1 is involved in the specification of neuroepithelium.     

The evolution of empty flowers revisited

The evolution of plants that provide no form of reward for their pollinators is puzzling because they receive low numbers of pollinator visits and so have low reproductive success. To predict the evolutionary dynamics of empty morphs within a plant population, we modeled different foraging strategies that pollinators could use to avoid them. We predicted that the optimal strategy was to visit empty inflorescences randomly when these were infrequent but to use strategies such as visiting fewer flowers per inflorescence to avoid wasting time on them. As the frequencies of empty inflorescences increased, discriminating directly against empty morphs was more likely to be an optimal strategy than was avoiding the species altogether and switching to an alternative one. An experimental test of this model using artificial inflorescences showed that bumblebees used a variety of strategies to minimize time wasted on empty inflorescences. They showed weak discrimination against empty inflorescences but switched to an alternative type of inflorescence as the frequency of empty inflorescences increased. We predicted that empty morphs would be at a visitation rate disadvantage even when at low frequencies in a plant population. Differences in outcrossing rates, or male function, may explain how rewardlessness spreads in a plant population.     

Reconstitution of lethally irradiated mice by cells isolated from adipose tissue

It is suggested that hematopoietic stem cells (HSC) could be found in several tissues of mesodermic origin. Among these, adipose tissue can expand throughout adult life and its expansion is not only due to mature adipocyte hypertrophy but also to the presence of precursor cells in stroma-vascular fraction (SVF). Here we report that transplantation of cells isolated from mice adipose tissue can efficiently rescue lethally irradiated mice and results in a reconstitution of major hematopoietic lineages. Donor cells can be detected in blood and in hematopoietic tissues of recipient mice. Adipose tissue contains a significant percentage of CD34, CD45 positive cells, and SVF cells were able to give rise to hematopoietic colonies in methylcellulose. We demonstrate the presence of hematopoietic progenitors in adipose tissue by phenotypic and functional characteristics. Thus adipose tissue could be considered as an important and convenient source of cells able to support hematopoiesis.     

Semicarbazide-sensitive amine oxidase activity exerts insulin-like effects on glucose metabolism and insulin-signaling pathways in adipose cells

Semicarbazide-sensitive amine oxidase (SSAO) is very abundant at the plasma membrane in adipocytes. The combination of SSAO substrates and low concentrations of vanadate markedly stimulates glucose transport and GLUT4 glucose transporter recruitment to the cell surface in rat adipocytes by a mechanism that requires SSAO activity and hydrogen peroxide formation. Substrates of SSAO such as benzylamine or tyramine in combination with vanadate potently stimulate tyrosine phosphorylation of both insulin-receptor substrates 1 (IRS-1) and 3 (IRS-3) and phosphatidylinositol 3-kinase (PI 3-kinase) activity in adipose cells, which occurs in the presence of a weak stimulation of insulin-receptor kinase. Moreover, the acute administration of benzylamine and vanadate in vivo enhances glucose tolerance in non-diabetic and streptozotocin-induced diabetic rats and reduces hyperglycemia after chronic treatment in streptozotocin-diabetic rats. Based on these observations, we propose that SSAO activity and vanadate potently mimic insulin effects in adipose cells and exert an anti-diabetic action in an animal model of type 1 diabetes mellitus.     

Pharmacological sensitivity of ATP release triggered by photoliberation of inositol-1,4,5-trisphosphate and zero extracellular calcium in brain endothelial cells

Recently, ATP has gained much interest as an extracellular messenger involved in the communication of calcium signals between cells. The mechanism of ATP release is, however, still a matter of debate. In the present study we investigated the possible contribution of connexin hemichannels or ion channels in the release of ATP in GP8, a rat brain endothelial cell line. Release of ATP was triggered by photoactivation of InsP(3) or by reducing the extracellular calcium concentration. Both trigger protocols induced ATP release significantly above baseline. InsP(3)-triggered ATP release was completely blocked by alpha-glycyrrhetinic acid (alpha-GA), the connexin mimetic peptides gap 26 and 27, and the trivalent ions gadolinium and lanthanum. ATP release triggered by zero calcium was, in addition to these substances, also blocked by flufenamic acid (FFA), niflumic acid, and NPPB. Gap 27 selectively blocked zero calcium-triggered ATP release in connexin-43 transfected HeLa cells, while having no effect in wild-type and connexin-32 transfected cells. Of all the agents used, only alpha-GA, FFA and NPPB significantly reduced gap junctional coupling. In conclusion, InsP(3) and zero calcium-triggered ATP release show major similarities but also some differences in their sensitivity to the agents applied. It is suggested that both stimuli trigger ATP release through the same mechanism, which is connexin-dependent, permeable in both directions, potently blocked by connexin mimetic peptides, and consistent with the opening of connexin hemichannels.