Variation of upwelling/oceanic conditions during the latest Pleistocene through Holocene off the central Peruvian coast: A diatom record

Diatoms are well preserved in partly laminated Holocene and late Pleistocene sediments on the upper continental slope of central Peru. Accumulation rates of diatom species previously recognized as tropical (oceanic, warm water) and subtropical (neritic, cooler water, upwelling) changed markedly downcore in Kasten cores obtained at 11°15′S, 12°58′S, and 13°37′S latitude. Subtropical species (e.g., Thalassiosira eccentrica “group”, Thalassiothrix frauenfeldii, Chaetoceros spp. resting spores, Delphineis spp.) predominated in late Pleistocene sediments of the two southern cores. A mix of tropical and subtropical diatom assemblages occurred in latest Pleistocene sediments, while tropical species (e.g., Coscinodiscus nodulifer/radiatus, Pseudoeunotia doliolus, Thalassionema nitzschioides var. parva) predominated in the late Holocene sediments. In the northern core latest Pleistocene sediments also contained a mix of tropical and subtropical species. Similarly, late Holocene sediments contained predominately tropical species of diatoms. Neoglacial periods (200–400 yr B.P., 2000–2700 yr B.P.), however, were sometimes characterized by a greater abundance of subtropical species and punctuated periodically with blooms of Skeletonema costatum and Rhizosolenia shrubsolei. It is proposed that during times of Southern Hemisphere cooling, Peruvian coastal waters north of 12°S were subjected to episodic mixing with warmer water masses before being overwhelmed by tropical waters that may have either passed southward across a weakened Equatorial Front or arose from intensified offshore countercurrents. Coastal waters south of 12°S latitude were probably unaffected by the tropical influence. Rather, these waters may have undergone intensified upwelling during the last Glacial epoch.     

HOMOCARNOSINOSIS: INCREASED CONTENT OF HOMOCARNOSINE AND DEFICIENCY OF HOMOCARNOSINASE IN BRAIN

Biochemical studies were carried out on a brain biopsy obtained from a 40 y old woman with homocarnosinosis. This patient and 2 of her siblings have a progressive neurological disorder characterized by spastic paraplegia, dementia and retinal pigmentation. Homocarnosine concentrations in their CSF, as well as in the CSF of their neurologically normal mother, are elevated 20-40-fold. Homocarnosine content was 4 times higher in the patient's frontal cortex than in biopsied cortex from a large group of control subjects. The activity of the synthetic enzyme, homocarnosine-carnosine synthetase. was not increased in the homocarnosinosis patient's brain. Homocarnosinase activity, however, was undetectable in the patient's brain biopsy, while it could readily be measured in comparable biopsies from control subjects. We conclude that homocarnosinase deficiency is probably inhcrited as an autosomal recessive trait, but that it is unlikely of itself to have caused the neurological syndrome affecting our patients.     

Uptake of deoxynivalenol by earthworms from <Emphasis Type="Italic">Fusarium</Emphasis>-infected wheat straw

Conservation tillage combined with crop-residue mulching is increasingly important to meet soil protection targets. Concurrently, the health risk of soil-borne pathogenic fungi like Fusarium species, which produce deoxynivalenol (DON) as their major mycotoxin, is increasing. The detritivorous earthworm species Lumbricus terrestris takes part in the efficient degradation of Fusarium-infected and DON-contaminated wheat straw. Against this background, a laboratory study was conducted to quantify by means of ELISA technique the uptake of DON and its possible absorption and accumulation in tissue by L. terrestris in the short-term (5 weeks) and long-term (11 weeks). The DON concentrations in L. terrestris of the Fusarium-infected treatment were significantly different in the order of gut tissue > body wall > gut content at both dates with a decline in the long-term. The DON concentrations in the tissues decreased by an order of magnitude of weeks to months.     

Adenosine deaminase complexing proteins of the rabbit

1. Complexing proteins isolated from the soluble and particulate fractions of rabbit kidney homogenates are structurally similar to complexing protein from human kidney. 2. The distribution of soluble and particulate complexing protein in other rabbit tissues is also similar to humans. 3. As in human kidney, complexing protein is localized in the glomeruli and proximal tubules of rabbit kidney. 4. The rabbit appears to be an appropriate animal model for the study of the adenosine deaminase complexing proteins in humans.