Substructural specificity and polyvalent carbohydrate recognition by the Entamoeba histolytica and rat hepatic N- acetylgalactosamine/galactose lectins

Both the Entamoeba histolytica lectin, a virulence factor for the causative agent of amebiasis, and the mammalian hepatic lectin bind to N-acetylgalactosamine (GalNAc) and galactose (Gal) nonreducing termini on oligosaccharides, with preference for GalNAc. Polyvalent GalNAc- derivatized neoglycoproteins have >1000-fold enhanced binding affinity for both lectins (Adler,P., Wood,S.J., Lee,Y.C., Lee,R.T., Petri,W.A.,Jr. and Schnaar,R.L.,1995, J. Biol. Chem ., 270, 5164-5171). Substructural specificity studies revealed that the 3-OH and 4-OH groups of GalNAc were required for binding to both lectins, whereas only the E.histolytica lectin required the 6-OH group. Whereas GalNAc binds with 4-fold lower affinity to the E.histolytica lectin than to the mammalian hepatic lectin, galactosamine and N-benzoyl galactosamine bind with higher affinity to the E. histolytica lectin. Therefore, a synthetic scheme for converting polyamine carriers to poly-N-acyl galactosamine derivatives (linked through the galactosamine primary amino group) was developed to test whether such ligands would bind the E.histolytica lectin with high specificity and high affinity. Contrary to expectations, polyvalent derivatives including GalN6lys5, GalN4desmosine, GalN4StarburstTMdendrimer, and GalN8StarburstTMdendrimer demonstrated highly enhanced binding to the mammalian hepatic lectin but little or no enhancement of binding to the E.histolytica lectin. We propose that the mammalian hepatic lectin binds with greatest affinity to GalNAc "miniclusters," which mimic branched termini of N-linked oligosaccharides, whereas the E.histolytica lectin binds most effectively to "maxiclusters," which may mimic more widely spaced GalNAc residues on intestinal mucins.      

Microbiological quality of tomato (<i>Solanum lycopersicum</i> L.) produced under greenhouse conditions in five Municipalities of the State of Mexico

The aim of the current research was to determine tomato (Solanum lycopersicum L.) microbiological quality produced under greenhouse conditions in 5 municipalities of the State of Mexico. Studies were conducted during the 2013 production cycle to know the risks and apply prevention strategies prior to its consumption. A microbiological analysis of samples of irrigation water, soil and 100 tomato fruits variety cid was performed to determine Aerobic Mesophiles, Total Coliforms and Fecal Coliforms. The methodology used were those according to the Official Mexican Standards NOM- 109-SSA1-1994, NOM-110-SSA1-1994, NOM-092-SSA1-1994, NOM-113-SSA1-1994, and the Regulations of the National French Organization for Standardization (AFNOR) NF V08-60, and NOM-093-SSA1-1994, which establish the allowable limits for the study microorganisms. The results showed a zero level of pollution in water and soil samples. For fruits, levels of Aerobic Mesophilic were within the maximum limits permitted by the standards. The municipality of Texcaltitlan showed the highest average for these microorganisms (10083.80 CFU/mL). Huixquilucan showed 2266.84 CFU/mL for Total Coliforms. For Fecal Coliforms, municipalities of Coatepec and Texcaltitlan exceeded the allowed limit.     

Inhibition of NF-κ B activity and cFLIP expression contribute to viral-induced apoptosis

Virus-induced activation of nuclear factor-kappa B (NF-B) is required for Type 3 (T3) reovirus-induced apoptosis. We now show that NF-B is also activated by the prototypic Type 1 reovirus strain Lang (T1L), which induces significantly less apoptosis than T3 viruses, indicating that NF-B activation alone is not sufficient for apoptosis in reovirus-infected cells. A second phase of virus-induced NF-B regulation, where NF-B activation is inhibited at later times following infection with T3 Abney (T3A), is absent in T1L-infected cells. This suggests that inhibition of NF-B activation at later times post infection also contributes to reovirus-induced apoptosis. Reovirus-induced inhibition of stimulus-induced activation of NF-B is significantly associated with apoptosis following infection of HEK293 cells with reassortant reoviruses and is determined by the T3 S1 gene segment, which is also the primary determinant of reovirus-induced apoptosis. Inhibition of stimulus-induced activation of NF-B also occurs following infection of primary cardiac myocytes with apoptotic (8B) but not non-apoptotic (T1L) reoviruses. Expression levels of the NF-B-regulated cellular FLICE inhibitory protein (cFLIP) reflect NF-B activation in reovirus-infected cells. Further, inhibition of NF-B activity and cFLIP expression promote T1L-induced apoptosis. These results demonstrate that inhibition of stimulus-induced activation of NF-B and the resulting decrease in cFLIP expression promote reovirus-induced apoptosis.     

A significant range extension and sanctuary for the rare Open Bay Island skink (Oligosoma taumakae)

Abstract

The Open Bay Island skink (Oligosoma taumakae) is one of New Zealand's rarest lizard species. Until 2010, it was known only from two small islands in the Open Bay Island Group, a Māori-owned wildlife sanctuary in South Westland, New Zealand. Skinks on these islands are threatened by predation from weka (Gallirallus australis), a flightless native rail thought to have been introduced to the Open Bay Islands c. 100 years ago. Here, we describe the discovery of Open Bay Island skinks on two vegetated rock stacks located off the coast of Barn Bay, 52 km southwest of the Open Bay Islands. Although small (c. 0.10 and 0.36 ha), the Barn Islands appear to be predator-free, providing an important sanctuary for the skinks. We recommend: (1) a survey of mainland sites with suitable habitat; and (2) an evaluation of the need for island biosecurity measures for detecting and responding to incursions of small mammals.     

Bilateral detection thresholds in dextrals and sinistrals reflect the more sensitive side of the nose, which is not lateralized [published erratum appears in Chem Senses 1998 Dec;23(6):761]

Several fundamental questions remain enigmatic concerning human olfactory sensitivity, including (i) whether detection threshold differences exist between the two sides of the nose (and, if so, whether such differences are influenced by handedness) and (ii) whether bilateral (i.e. binasal) stimulation leads to lower thresholds than unilateral stimulation (and, if so, whether the degree of facilitation is inversely related to general olfactory ability). In this study, and well-validated single staircase procedure was used to establish bilateral and unilateral detection thresholds for the cranial nerve I stimulant phenyl ethyl alcohol in 130 right- and 33 left-handed subjects. No differences in sensitivity between the left and right sides of the nose were observed in either group. Bilateral thresholds were lower, on average, than unilateral thresholds when the latter were categorized in terms of left and right nares. However, the bilateral thresholds did not differ significantly from those of the side of the nose with the lower threshold. Overall smell ability, as measured by the University of Pennsylvania Smell Identification Test, did not interact with any of the test measures. These data imply that (i) the left and right sides of the nose do not systematically differ in detection threshold sensitivity for either dextrals or sinistrals and (ii) if central integration of left:right olfactory threshold sensitivity occurs, its effects do not exceed the function of the better side of the nose.      

Morphogenic Regulation of Pathotoxin Synthesis in Cochliobolus carbonum

The fungus Cochliobolus carbonum causes leaf spot disease of maize. Highly virulent isolates of the pathogen produce a host-selective, peptide toxin that is active against susceptible genotypes of maize. Prior to infection, spores must germinate and differentiate appressoria, structures specialized for leaf penetration. Analysis of spore germination fluids by plasma desorption mass spectrometry, which allowed detection of as little as 0.5 ng toxin, revealed that spores induced to form appressoria in vitro synthesized and released the toxin at a time coincident with maturation of appressoria. Spores incubated under conditions that did not induce appressorium formation failed to produce toxin. These observations indicate that synthesis of the host-selective toxin, which is essential for successful pathogenesis of maize by C. carbonum, is regulated by infection-related morphogenesis.     

Chemical biology: Paper alert

A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in chemical biology.