Metabolic engineering,new antibiotics and biofilm viscoelasticity

In the following highlight we refer to a number of new advances in the field of Biotechnology that address issues relating to the synthesis of new antibiotics, new biocatalysts and matrices in biofilms.     

Effects of habitat fragmentation and disturbance on howler monkeys: a review

We examined the literature on the effects of habitat fragmentation and disturbance on howler monkeys (genus Alouatta) to (1) identify different threats that may affect howlers in fragmented landscapes; (2) review specific predictions developed in fragmentation theory and (3) identify the empirical evidence supporting these predictions. Although howlers are known for their ability to persist in both conserved and disturbed conditions, we found evidence that they are negatively affected by high levels of habitat loss, fragmentation and degradation. Patch size appears to be the main factor constraining populations in fragmented habitats, probably because patch size is positively related to food availability, and negatively related to anthropogenic pressures, physiological stress and parasite loads. Patch isolation is not a strong predictor of either patch occupancy or population size in howlers, a result that may be related to the ability of howlers to move among forest patches. Thus, we propose that it is probable that habitat loss has larger consistent negative effects on howler populations than habitat fragmentation per se. In general, food availability decreases with patch size, not only due to habitat loss, but also because the density of big trees, plant species richness and howlers' home range size are lower in smaller patches, where howlers' population densities are commonly higher. However, it is unclear which vegetation attributes have the biggest influence on howler populations. Similarly, our knowledge is still limited concerning the effects of postfragmentation threats (e.g. hunting and logging) on howlers living in forest patches, and how several endogenous threats (e.g. genetic diversity, physiological stress, and parasitism) affect the distribution, population structure and persistence of howlers. More long‐term studies with comparable methods are necessary to quantify some of the patterns discussed in this review, and determine through meta‐analyses whether there are significant inter‐specific differences in species' responses to habitat loss and fragmentation. Am. J. Primatol. 72:1–16, 2010. © 2009 Wiley‐Liss, Inc.     

Newly discovered penicillin acylase activity of aculeacin A acylase from Actinoplanes utahensis

Aculeacin A acylase from Actinoplanes utahensis produced by Streptomyces lividans revealed acylase activities that are able to hydrolyze penicillin V and several natural aliphatic penicillins. Penicillin K was the best substrate, showing a catalytic efficiency of 34.79 mM(-1) s(-1). Furthermore, aculeacin A acylase was highly thermostable, with a midpoint transition temperature of 81.5 degrees C.     

Curcumin and cyclopalladated complexes: a recipe for bifunctional biomaterials

The first examples of binuclear and mononuclear ortho-palladated complexes based on a functionalized 2-phenylquinoline ligand have been synthesized and fully characterized. Conjugating cyclopalladated fragments to curcumin family biologically active beta-diketones gives in one single molecule two different functionalities. The structural variations based on the curcuminoid structure have been tested for their in vitro cytotoxic activity. The activity of complexes comprised of a cyclopalladated fragment conjugated to functionalized bioactive ligands, represents the potential of organometallic systems in generating new bifunctional biomaterials.     

Crh1p and Crh2p are required for the cross-linking of chitin to beta(1-6)glucan in the Saccharomyces cerevisiae cell wall

In budding yeast, chitin is found in three locations: at the primary septum, largely in free form, at the mother-bud neck, partially linked to beta(1-3)glucan, and in the lateral wall, attached in part to beta(1-6)glucan. By using a recently developed strategy for the study of cell wall cross-links, we have found that chitin linked to beta(1-6)glucan is diminished in mutants of the CRH1 or the CRH2/UTR2 gene and completely absent in a double mutant. This indicates that Crh1p and Crh2p, homologues of glycosyltransferases, ferry chitin chains from chitin synthase III to beta(1-6)glucan. Deletion of CRH1 and/or CRH2 aggravated the defects of fks1Delta and gas1Delta mutants, which are impaired in cell wall synthesis. A temperature shift from 30 degrees C to 38 degrees C increased the proportion of chitin attached to beta(1-6)glucan. The expression of CRH1, but not that of CRH2, was also higher at 38 degrees C in a manner dependent on the cell integrity pathway. Furthermore, the localization of both Crh1p and Crh2p at the cell cortex, the area where the chitin-beta(1-6)glucan complex is found, was greatly enhanced at 38 degrees C. Crh1p and Crh2p are the first proteins directly implicated in the formation of cross-links between cell wall components in fungi.     

Geographical variation in cloacal microflora and bacterial antibiotic resistance in a threatened avian scavenger in relation to diet and livestock farming practices

The impact on wildlife health of the increase in the use of antimicrobial agents with the intensification of livestock production remains unknown. The composition, richness and prevalence of cloacal microflora as well as bacterial resistance to antibiotics in nestlings and full-grown Egyptian vultures Neophron percnopterus were assessed in four areas of Spain in which the degree of farming intensification differs. Differences in diet composition, especially the role of stabled livestock carrion, appear to govern the similarities of bacterial flora composition among continental populations, while the insular vulture population (Fuerteventura, Canary Islands) showed differences attributed to isolation. Evidence of a positive relationship between the consumption of stabled livestock carrion and bacterial resistance to multiple antibiotics was found. Bacterial resistance was high for semisynthetic penicillins and enrofloxacin, especially in the area with the most intensive stabled livestock production. The pattern of antibiotic resistance was similar for the different bacterial species within each area. Bacterial resistance to antibiotics may be determined by resistance of bacteria present in the livestock meat remains that constituted the food of this species, as indicated by the fact that resistance to each antibiotic was correlated in Escherichia coli isolated from swine carrion and Egyptian vulture nestlings. In addition, resistance in normal faecal bacteria (present in the microflora of both livestock and vultures) was higher than in Staphylococcus epidermidis, a species indicator of the transient flora acquired presumably through the consumption of wild rabbits. Potential negative effects of the use of antimicrobials in livestock farming included the direct ingestion of these drug residues and the effects of bacterial antibiotic resistance on the health of scavengers.     

Oviposition behaviour and larval development of Anastrepha fraterculus from Argentina in citrus

Citrus peel physicochemical attributes are considered the main components conferring partial or even total resistance to fruit fly (Diptera: Tephritidae) infestation. Fruit fly females adapt their ovipositional strategies to overcome such resistance. Here, we explored the effects of citrus species (Rutaceae) on the ovipositional behaviour of the South American fruit fly, Anastrepha fraterculus (Wiedemann), and on its immature development. Particularly, we investigated the effects of (1) citrus species on oviposition behaviour and immature development, (2) citrus species on oviposition preference and on the location of the eggs at different depth in the citrus peel, and (3) harvest season and post‐harvest storage time on oviposition behaviour and immature development in lemon. Citrus species influenced ovipositional behaviour and affected survival of immature stages. Females laid eggs in lemon [Citrus limon (L.) Burm.], orange [Citrus sinensis (L.) Osbeck], and grapefruit (Citrus paradisi Macfadyen). In orange and lemon, larvae were found dead close to the oviposition areas, suggesting chemically mediated resistance mechanisms. Under choice conditions, females preferred grapefruit over lemon and bigger clutches were found in the layers where embryonic development is favoured. Unsuitability of lemon as a medium to complete development was neither affected by harvest season nor by storage time of the fruit after harvest. The physical and chemical characteristics of the peel were distinctive to each citrus species and may have affected the specific levels of resistance of these citrus species to infestation by A. fraterculus.