Middle region of the Borrelia burgdorferi surface‐located protein 1 (Lmp1) interacts with host chondroitin‐6‐sulfate and independently facilitates infection

Borrelia burgdorferi surface‐located membrane protein 1, also known as Lmp1, has been shown to play critical roles in pathogen evasion of host‐acquired immune defences, thereby facilitating persistent infection. Lmp1 possesses three regions representing potentially discrete domains: Lmp1N, Lmp1M and Lmp1C. Because of its insignificant homology to known proteins, how Lmp1 or its specific regions contribute to microbial biology and infection remains enigmatic. Here, we show that distinct from Lmp1N and Lmp1C, Lmp1M is composed of at least 70% alpha helices and completely lacks recognizable beta sheets. The region binds to host glycosaminoglycan chondroitin‐6‐sulfate molecules and facilitates mammalian cell attachment, suggesting an adhesin function of Lmp1M. Phenotypic analysis of the Lmp1‐deficient mutant engineered to produce Lmp1M on the microbial surface suggests that Lmp1M can independently support B. burgdorferi infectivity in murine hosts. Further exploration of functions of Lmp1 distinct regions will shed new light on the intriguing biology and infectivity of spirochetes and help develop novel interventions to combat Lyme disease.     

Benthic diatoms in the salinas of the Dry Creek saltfields,South Australia

Given that diatom assemblages are a well-recognised method of characterising the water quality in freshwater streams, it seems reasonable to investigate its applicability to solar saltfields. A summer collection of benthic diatoms was undertaken in the salinas of the Dry Creek solar saltfields in South Australia for this purpose. The facility inputs seawater both from a low nutrient samphire creek and poorer quality, high nutrient samphire creek. Salinity and nutrient status of the pools and concentrating salinas have been thoroughly characterized over many years. The addition of JJ periphytometers to the sampling regime in the summer of 2001–2002 allowed the collection of benthic diatoms from these sites. Of the 69 species collected during the study, 16 species occurred only in oligotrophic waters with salinities less than 70 g/l TDS (total dissolved solids). Twenty species of diatoms occurred only in the eutrophic waters with salinities less than 70 g/l TDS, eight species were restricted to the hypersaline ponds and the remainder were undiscriminating in their ecological preferences. Guest Editor: John M. Melack Saline Water and their Biota     

HOMOPLASY AS PATTERN: MULTIVARIATE ANALYSIS OF MORPHOLOGICAL CONVERGENCE IN ANSERIFORMES

Abstract— A multivariatc model for taxa and characters is presented that represents taxa as points in an ordination space such that shared derived character states define groups of taxa or regions in this space. This model is compared, in terms of concepts of information content and explanatory power, to the eladistie model that relates characters and taxa to a hierarchical pattern. While a cladogram may be identified with a phylogenetic hypothesis, the ordination pattern may be equated with hypotheses about similarities among the taxa in habitat, feeding mode, or other ecological factors.
This basic data-pattern model is appropriate for the explanation of the character convergences implied by a particular phylogenetic hypothesis. Under the assumptions of the model, the underlying ordination pattern may be inferred from the observed character data using robust ordination procedures recently developed in community ecology.
As an illustration of the method, the morphological convergences derived from a recent phylogenetic hypothesis for genera of Anseriformes are analysed. In the resulting two-dimensional ordination, the genera are arranged such that the convergenlly derived states form regions in the space. While this pattern implies that some of the taxa that are close together in the space are phylogcnetically dissimilar , taxa that are close together in the space are found to be similar in their mode of feeding. Thus, the ordination demonstrates that taxa sharing these morphological convergences tend to utilize habitat in the same way in terms of mode of feeding.
The explanatory power of the pattern and the degree of recovery of habitat information are tested against null hypotheses using Monte Carlo simulations.
Extensions of the method are discussed, including applications to studies of parasite—host relationships and to biogeography.     

Bacillus thuringiensis Sporulation at Suboptimal Temperature

Bacillus thuringiensis var. thuringiensis Berliner grown at 14 C on a chemically defined liquid medium slowly produced spores and parasporal inclusions. Sporulation ultimately attained 50 to 100% of that of cultures grown at 30 C.     

Polarity: the role of localized secretion

Studies of single cells from brown algae suggest that localized secretions stabilize the polar axis resulting in an asymmetry in the cell wall. This cortical asymmetry appears to play a role in orienting the plane of cell division and in determining the different fates of the resulting daughter cells. Recent studies indicate that similar processes may operate in seed plants.