The Jehol Biota (Lower Cretaceous,China): new discoveries and future prospects

Continuing work on the paleontology and sedimentology of the Jehol Group (Lower Cretaceous, China) is yielding numerous new insights into the evolution of many Mesozoic plant and animal clades. Nevertheless, many questions remain unanswered regarding Jehol paleoenvironments, paleobiology and paleobiogeography. All of this information will be crucial in providing a detailed reconstruction of this extinct ecosystem.     

Inhibition of enzymatic synthesis of pantothenate by 2,3-dichloroisobutyrate

The investigations reported here have shown that 2,3-dichloroisobuty-rate is uncompetitive with beta-alanine and competitive with pantoate for a site on the enzyme of pantothenate synthesis. The enzyme dissociation constant of the inhibitor was comparable to that of the competitive substrate.     

Effect of increased liver glycogen and liver weight on liver function in rainbow trout, Salmo gairdneri Richardson: recovery from anaesthesia and plasma 35S-sulphobromophthalein clearance

Abstract. Juvenile rainbow trout (initial mean body weight 17 g) reared on practical trout diets containing different levels of available carbohydrate for 8–24 weeks were assayed for liver function based on the time required to recover from the anaesthetics tricaine methanesulphonate (MS222), 2-phenoxyethanol (2PE) and tertiary-amyl alcohol (TAA), as well as plasma clearance of ³⁵S-sulphobromo-phthalein (BSP), Liver/body weight ratios (LBW) and percentage liver glycogen content (LG) increased in a linear manner with increased available carbohydrate. The mean recovery time (MRT) of trout anaesthetized with 2PE and TAA increased linearly with increased LBW and LG. No difference was observed in the MRT of trout anaesthetized with MS222 which is not metabolized in the trout liver. There was a significant linear regression of the biological half-life of plasma BSP on LBW (MR²= 95.7) and LG (MR²= 99.6). The results indicate that increased liver glycogen and liver weight due to higher levels of available carbohydrate affect the liver function of rainbow trout. These liver function tests may be applicable in determining acceptable levels of available carbohydrate in practical trout diets.     

A sixteen-year record of regional and temporal variation in the fruiting of beech (Fagus sylvatica L.) in England (1980-;1995)

Annual production of mast by the beech is highly variable, yetthere are few long-term records of the extent of masting whichmight help to explain the masting phenomenon. In this 16-yearstudy, beech mast has been sampled from 100 trees by 7-min samplescollected from the ground and from low-growing branches at sitesranging from the south to the north of England, and varyingfrom closed canopy beechwood to shelter belts, avenues and isolatedtrees in parks. Variation in production of viable seed is much greater fromyear to year than from north to south. Good masting occurredin 1980, 1982, 1984, 1990 and 1995: in these years at leastone year of very bad masting normally followed. Otherwise, predictionof masting is unreliable. No full mast was found in 1981. Overallthere was very little full mast in five other years, but evenin these years, some sites or some trees produced an appreciableamount. All trees produced empty pericarps as well as full mast, especiallyon lower or shaded branches. Isolated trees produced more emptypericarps than trees in groups; this is likely to result froma lack of cross pollination. It is concluded that ground samplingfor a fixed period affords a rapid and effective method of assessingmasting despite the factors intervening between mast sheddingand collection.     

The adsorption and degradation of glyphosate in five Hawaiian sugarcane soils*

The rate of aerobic evolution of ¹⁴CO₂ from ¹⁴C-glyphosate labelled in the methylphosphonyl carbon, varied 100-fold within a group of five Hawaiian sugarcane soils. The rate depended inversely on the degree of soil binding, probably associated with the phosphonic acid moiety, and to a less certain extent on soil pH and soil organic matter. After an initial rapid degradation, the rate of ¹⁴CO₂ evolution in three soils reached a constant at 16–21 days which continued to the 60-day termination. The other two soils showed a continually decreasing rate throughout. Two soils released over 50% of the labelled carbon in 60 days, a third released 35%, while the remaining soils released 1.2 and 0.8% respectively. Labelled carbon in the soils after 60 days consisted of glyphosate and one metabolite, aminomethyl-phosphonic acid, with glyphosate predominating in high fixing soils. The ¹⁴C could be extracted almost completely with NaOH solution, and remained mainly in solution after acidification.     

THE COMPUTED TOMOGRAPHIC APPEARANCE OF EQUINE TEMPOROHYOID OSTEOARTHROPATHY

Equine temporohyoid osteoarthropathy is characterized by progressive osseous proliferation of the temporohyoid articulation and surrounding structures. The diagnosis has generally been made using radiography and endoscopy of the guttural pouch. Recently, computed tomography (CT) has been used in the diagnosis of temporohyoid osteoarthropathy. This study was performed to determine the CT imaging characteristics of temporohyoid osteoarthropathy and to compare these to radiographic and endoscopic findings. CT scans from 16 horses with a final diagnosis of temporohyoid osteoarthropathy were reviewed. Five horses that had undergone CT scan for reasons other than temporohyoid osteoarthropathy were included as controls. Qualitative and quantitative data were used to describe the magnitude of the CT findings. Osseous proliferation of the stylohyoid bone and temporohyoid articulation was found to be a consistent feature of temporohyoid osteoarthropathy. Thickening of the ceratohyoid bone and proliferation of its articulation with the stylohyoid bone was frequently identified and this finding may have surgical implications. Horses with neurologic deficits had increased stylohyoid width that was significantly different than the subclinically affected side. CT evaluation also allowed the identification of subclinical bilateral disease in horses thought to be unilaterally affected based on clinical examination.     

Influence of dietary selenium on the occurrence of nephrocalcinosis in the rainbow trout, Salmo gairdneri Richardson

Abstract Rainbow trout were fed practical-type diets containing 0.6, 6.6 and 114 μ g/g selenium for 16 weeks at approximately 15°C. Fish reared on the highest levels of dietary selenium had a significant reduction in final body weight, feed: gain ratio and increased mortality. Haematocrit, plasma calcium, glucose, and protein levels did not vary significantly. Ninety per cent of the fish fed the diet containing the highest level of selenium developed nephrocalcinosis. Fish with occult nephrocalcinosis had significantly increased levels of kidney calcium and those with overt nephrocalcinosis had significantly increased levels of kidney calcium and magnesium, and liver magnesium. Microscopically, the majority of renal damage was tubular with the renal interstitium becoming inflamed only when tubules degenerated. The pathogenesis of selenium-induced nephrocalcinosis is discussed.