Fate of endosulfan in rats and toxicological considerations of apolar metabolites

[¹⁴C]Endosulfan, α or β isomers separately, was administered to rats as a single oral dose and as a dietary supplement for 14 days. No appreciable differences were observed in the fate of the two isomers. Five days after the single dose, 75% of the dose had been voided in the feces and 13% in the urine. Of the total radiocarbon consumed in the diet after 14 days, 56% had been eliminated in the feces and 8% in the urine. Bile collection studies showed that up to 47% of a single oral dose was eliminated from the liver via this route; enterohepatic circulation was not apparent. Maximum [¹⁴C]endosulfan equivalents in body tissue occurred in the kidney and liver, 3 and 1 ppm, respectively, after 14 days of feeding 5 ppm of endosulfan. Apolar metabolites in the excreta and/or tissues were a minor portion of the total residues and consisted of the sulfate, diol, α-hydroxy ether, lactone, and ether derivatives of endosulfan. The sulfate was slightly more toxic to mice than endosulfan, while the other products were less toxic. Neither endosulfan nor its metabolites were active in the Salmonella mutagenicity test. Endosulfan in the diet of rats for 28 days at 50 ppm did not induce liver oxidase enzymes, alter liver or kidney weights, or influence the rate of weight gain of the animals.     

Ultrasonographic monitoring of artificially stimulated ejaculation in three rhinoceros species (Ceratotherium simum, Diceros bicornis, Rhinoceros unicornus).

Manual massage of the penis and rectal electroejaculation methods have been minimally effective for collecting semen from the rhinoceros. These two methods for stimulating ejaculation were evaluated by rectal ultrasonography. One individual each of three rhinoceros species (Ceratotherium simum simum, Rhinoceros unicornis and Diceros bicornis) was stimulated by manual massage of the penis and two black rhinoceroses (Diceros bicornis) were electroejaculated. On ultrasonography, neither manual massage nor rectal electroejaculation affected the accessory glands. The pelvic urethra remained empty during manual massage of unconditioned animals; however, this area was filled before commencement of massage of conditioned animals. The pelvic urethra also filled during electroejaculation. Semen accumulated in the pelvic urethra during pauses between electrical stimulations and was moved distally into the penile urethra by rectal and penile massage. The volumes of seminal fluid recovered from electroejaculation in this study exceeded previously reported attempts. This study demonstrated the potential of transrectal imaging for improving the recovery of semen by these methods.     

The turnover of organic carbon in subsoils. Part 1. Natural and bomb radiocarbon in soil profiles from the Rothamsted long-term field experiments

The Rothamsted long‐term field experiments, started more than 150 years ago, provide unique material for the study of carbon turnover in subsoils. Total organic C, ¹⁴C and ¹³C were measured on soil profiles taken from these experiments, before and after the thermonuclear bomb tests of the mid‐20th century. Four contrasting systems of land management were sampled: land cultivated every year for winter wheat; regenerating woodland on acid soil; regenerating woodland on calcareous soil; and old grassland. The mean radiocarbon ages of all the pre‐bomb samples from cultivated land were 1210 years (0–23 cm), 2040 years (23–46 cm), 3610 years (46–69 cm) and 5520 years (69–92 cm). Bomb radiocarbon derived from thermonuclear tests was present throughout the profile in all the post‐bomb samples, although below 23 cm the amounts were small and the pre‐ and post‐bomb radiocarbon measurements were often not significantly different. Values of δ¹³C increased down the profile, from ?26.3‰ (0–23 cm layer, mean of all measurements) to ?25.2‰ for the 69–92 cm layer. The C/N ratios decreased with depth in virtually all of the profiles sampled. Excluding the surface (0–23 cm) soils from the old grassland, the hyperbola m = 152.1 ? 2341/(1 + 0.264n) gave a close fit to the radiocarbon data from all depths, all sampling times and all sites, where n is the organic C content of the soil, in t ha^?1, and m is the radiocarbon content of the soil, in Δ¹⁴C units, corrected for expansion or contraction of soil layers with time. The aberrant grassland soils almost certainly contained coal: one of them was shown by ¹³C‐NMR to contain 0.82% coal C. In Part 2 (this issue) of this pair of papers, these radiocarbon and total C measurements are used to develop and test a new model for the turnover of organic C in subsoils.     

Morphology and nutritive value of perennial ryegrass cultivars at different phenological stages

Eight perennial ryegrass cultivars (representing the variations in ploidy, heading date and water‐soluble carbohydrates concentration) were investigated for morphology and nutritive value at three phenological stages: pre‐heading vegetative, reproductive and post‐flowering vegetative stages. Chemical compositions and digestibility of morphological components (lamina, pseudostem and reproductive stem) from each perennial ryegrass cultivar were analysed in a split‐plot design. At the vegetative stages, perennial ryegrass cultivars differed significantly in the proportions of lamina and pseudostem. Tetraploid cultivars, Base and Bealey, always had the greatest lamina proportion (51.8% and 53.2% at the pre‐heading and post‐flowering vegetative stages respectively). At the reproductive stage, the emergence of seed heads diminished the differences in morphology among cultivars. Perennial ryegrass cultivars also had distinct nutritive value throughout three phenological stages. The high‐sugar cultivar, AberMagic, had high WSC concentrations (276, 227 and 90 g/kg DM at the pre‐heading vegetative, reproductive and post‐flowering vegetative stages respectively); the intermediate‐heading cultivars, Kamo and Commando, generally had a lower organic matter digestibility in dry matter than the late‐heading cultivars at the pre‐heading vegetative (70.7% vs. 74.4%) and reproductive stage (63.9% vs. 68.2%). However, although the morphological components were different in nutritive value consistently, the differences in morphology did not account for the variation in nutritive value among perennial ryegrass cultivars.     

Deforestation and forest degradation in Papua New Guinea

? The Government of Papua New Guinea (PNG) has played a prominent part in recent negotiations for “rainforest nations” to be compensated for reducing greenhouse gas emissions from deforestation or forest degradation (DFD).

? A new report “The State of the Forests of Papua New Guinea” claims that rates of DFD in PNG are much higher than have previously reported. It suggests more than half of PNG’s remaining forests will have disappeared or be damaged beyond recovery by 2021.

? We argue that this claim is incorrect. The report overestimates the area of intact primary forest in 1972 and the impact of traditional land use practices on forest cover. Much of what the RSLUP report considers as deforestation is part of a cycle of traditional clearance for farming, fallow and regrowth that has been occurring for hundreds of years.

? The assumption that areas impacted by harvesting or shifting cultivation will inevitably degrade and become non-forest is also not supported by observation of cutover forest in PNG. A considerable proportion of cutover forest areas will recover carbon stocks after harvesting.

? It is argued that traditional land use practices and forest recovery processes need to be considered in assessing greenhouse gas emissions from deforestation and degradation in countries with complex land use histories such as PNG.