Hill-Chao numbers allow decomposing gamma multifunctionality into alpha and beta components

Biodiversity-ecosystem functioning (BEF) research has provided strong evidence and mechanistic underpinnings to support positive effects of biodiversity on ecosystem functioning, from single to multiple functions. This research has provided knowledge gained mainly at the local alpha scale (i.e. within ecosystems), but the increasing homogenization of landscapes in the Anthropocene has raised the potential that declining biodiversity at the beta (across ecosystems) and gamma scales is likely to also impact ecosystem functioning. Drawing on biodiversity theory, we propose a new statistical framework based on Hill-Chao numbers. The framework allows decomposition of multifunctionality at gamma scales into alpha and beta components, a critical but hitherto missing tool in BEF research; it also allows weighting of individual ecosystem functions. Through the proposed decomposition, new BEF results for beta and gamma scales are discovered. Our novel approach is applicable across ecosystems and connects local- and landscape-scale BEF assessments from experiments to natural settings.

Overproduction of three genes leads to camphor resistance and chromosome condensation in Escherichia coli

We isolated and characterized three genes, crcA, cspE and crcB, which when present in high copy confer camphor resistance on a cell and suppress mutations in the chromosomal partition gene mukB. Both phenotypes require the same genes. Unlike chromosomal camphor resistant mutants, high copy number crcA, cspE and crcB do not result in an increase in the ploidy of the cells. The cspE gene has been previously identified as a cold shock-like protein with homologues in all organisms tested. We also demonstrate that camphor causes the nucleoids to decondense in vivo and when the three genes are present in high copy, the chromosomes do not decondense. Our results implicate camphor and mukB mutations as interfering with chromosome condensation and high copy crcA, cspE and crcB as promoting or protecting chromosome folding.

Occupational risk and the development of premalignant skin lesions among paraquat manufacturers

The objective of this study was to determine the prevalence rate and possible aetiological factors of premalignant skin lesions observed among paraquat manufacturers. A total of 228 workers in 28 factories were interviewed and independently examined by a dermatologist during site inspection in 1985. Information concerning past working experience, current toxic exposures, other risk factors of hyperpigmented macules and keratosis, and the past and present manufacturing processes of each factory was collected. Sixty nine cases of hyperpigmented macules and 17 of hyperkeratosis were found. Typical macules were irregular in shape, pin head size, hyperpigmented, with or without hyperkeratosis, and usually distributed symmetrically over the forearms, hands, neck, and upper chest, where exposure to sunlight was maximal. Six patients with hyperkeratotic lesions subsequently had biopsies performed and two showed Bowenoid changes. Eighty per cent (28 cases) and 67% (38 cases) of workers developed hyperpigmented macules if they had ever been engaged in bipyridine centrifugation and crystallisation, respectively; there were three workers 3% with such lesions among those who performed packaging or administrative jobs, or both. There was a significant trend (p less than 0.0001) for workers to develop hyperpigmented macules and hyperkeratosis the longer they had been exposed to centrifugation or crystallisation, or both, independent of age and the duration of exposure to sunlight. Evidence is presented to suggest that sunlight is a necessary cofactor and that the aetiological agent was produced during high temperature sodium process of bipyridine synthesis, and possibly bipyridine isomer(s).

A new approach for determining the volume of cerebral cellular fluid and demonstration of its communication with C.S.F

1. A new technique is presented for determining the volume of extracellular space in bowfin (Amia calva) brain during in vitro incubation. It consists of solving simultaneous equations which are applied to determine the volume of extracellular space as well as intracellular marker concentration. This technique allows for a better insight into the redistribution of marker between incubation medium and extracellular space as well as between extracellular and intracellular space.2. Na(+), K(+) and Cl(-) equilibrated within 10-15 min between incubation medium and extracellular space. There was no evidence of a homoeostatic mechanism controlling the concentration of these ions in the extracellular fluid, which appeared to be in equilibrium with cerebrospinal fluid. The extracellular spaces of these ions were identical: Na(+), 23.4; K(+), 23.3 and Cl(-), 23.2%.3. Sorbitol equilibrated with the extracellular fluid within 45 min and indicated an extracellular space of 22.6%, nearly identical with that for electrolytes.4. Vastly different ;spaces' were obtained for [(3)H]methoxy inulin, which equilibrated within 45 min with a 13% space and [(14)C]carboxyl inulin, which showed a 46% space value for only 30 min. The difference may be explained by marker decomposition. The 9% difference between the [(3)H]methoxy inulin and sorbitol spaces may be explained by a ;packing' factor attributable to molecular size.

Axon calibre, neurofilaments, microtubules, sheath thickness and cholesterol in cat optic nerve fibres

Images