Postirradiation modification of tumor blood flow: a method to increase the effectiveness of chemical radiosensitizers

The effect of postirradiation hypoxia induced by administration of the vasodilator hydralazine on the efficacy of misonidazole and RSU-1069 used in combination with radiation has been evaluated. Studies with the Lewis lung carcinoma indicate that hydralazine at a dose of 5 mg/kg reduces tumor blood flow and consequently increases the amount of hypoxia in the tumor tissue. Administration of hydralazine immediately after radiation treatment increased the amount of cell kill. However, the increase in cell kill was more pronounced when hydralazine was used in treatment regimes in which misonidazole (0.2 mg/g) or RSU-1069 (0.02 mg/g) was administered pre- or postirradiation. The finding that similar effects are observed if the nitroimidazoles were administered either before or after radiation in the regimes involving hydralazine suggests that the enhanced cell killing observed is due to hypoxic cell cytotoxicity. In contrast to the effects of hydralazine on the response of tumors to radiation plus misonidazole or RSU-1069, it has no effect on the response of mouse intestine to such treatment regimes. Thus therapeutic gain may accrue from the use of hydralazine in radiation treatments which incorporate the nitroimidazole radiosensitizers misonidazole and RSU-1069.     

Cytochrome b-245 from human neutrophils is a glycoprotein.

Cytochrome b-245 is a glycoprotein. It runs as a broad band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and its apparent Mr varies with the concentration of acrylamide. It stained positively with Schiff reagent and with silver stains after oxidation with periodic acid. It preferentially bound the lectin of Phaseolus vulgaris (type III), and cleavage of carbohydrate with endoglycosidase F resulted in a sharp band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis with an apparent Mr of 55000 G.l.c. analysis of carbohydrate showed this to account for about 15% of the Mr and N-acetylglucosamine and galactose to be the major sugars.     

The use of tooth eruption and wear, body weight and antler characteristics in the age estimation of male wild and park Fallow deer (Dama dama)

The eruption and wear of the cheek teeth of male Fallow deer from a park and wild population has been studied for age determination purposes. It was found possible to age accurately up to 48 months animals whose date of death was known, whether they were from a wild or park population. It was found that up to at least this age individual and environmental differences affecting animals born in successive years did not mask those resulting fromthe restricted seasonal breeding of this species.
Antler development and body weight were studied in relation to the ages obtained and were found to be of limited value for age estimation.     

Physiology, thermoregulation and bipedalism

It has long been recognized that the bipedal posture reduces the surface area of the body exposed to the sun. In recent years, a theory has been developed by Wheeler that bipedalism evolved in the ancestor of the Hominidae in order to help relieve thermal stress on the animals in open equatorial environments. Bipedalism was said to afford a distinct adaptive advantage over quadrupedalism by permitting hominids to remain active in the open throughout the day. The heat load of the hypothetical hominid comprises the external environment as modelled by Wheeler and the animal's internal environment (i.e., the internal heat generated by its metabolic and locomotor activities, and its evaporative and respirative cooling capacities). When these factors are integrated in the calculation of the animal's thermal budget, the putative advantage of the bipedal over the quadrupedal posture is considerably reduced. The simulations conducted in this study suggest that the increased time afforded to early hominids in the open by bipedalism was relatively short and, therefore, of little or no adaptive significance. These results suggest that thermoregulatory considerations cannot be implicated as a first cause in the evolution of bipedalism in the hominid ancestor.     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

An energetic analysis of host plant selection by the large milkweed bug,Oncopeltus fasciatus

Summary The large milkweed bug, Oncopeltus fasciatus, is a specialized seed feeder that has been observed completing nymphal development in the field on only a small proportion of its potential host species within the genus Asclepias. In central Missouri only two of the six milkweed species studied, A. syriaca and A. verticillata, commonly supported nymphal O. fasciatus growth in the field. The seed of all six species, however, was equally suitable food for bugs reared in the laboratory. In laboratory preference tests, adult bugs chose to feed on the largest seeds, A. hirtella, but such a preference could not explain the observed field feeding patterns.One explanation to account for the observed host plant selection is based upon an energetic analysis. Only A. syriaca provided enough seed biomass for a clutch of O. fasciatus nymphs to develop on a single plant, and only A. verticillata grew in high enough density that a clutch could find sufficient food within the limited range of nymphal movement. These results illustrate a corollary of the resource concentration hypothesis: within a plant group whose members share similar secondary plant chemistries, the only species that will be viable hosts for a specialized herbivore are those that provide the minimal resource density necessary for the completion of nymphal development.In central Missouri, O. fasciatus has specialized on a critical resource density, not traits of individual Asclepias species. The appearance of host selection within the potential host plant spectrum is the result of a characteristic growth form, seed output, and dispersion pattern for each milkweed species that makes some species much more likely than others to produce sufficient seed resources.     

Landscape simplification increases vineyard pest outbreaks and insecticide use

Diversifying agricultural landscapes may mitigate biodiversity declines and improve pest management. Yet landscapes are rarely managed to suppress pests, in part because researchers seldom measure key variables related to pest outbreaks and insecticides that drive management decisions. We used a 13‐year government database to analyse landscape effects on European grapevine moth (Lobesia botrana) outbreaks and insecticides across c. 400 Spanish vineyards. At harvest, we found pest outbreaks increased four‐fold in simplified, vineyard‐dominated landscapes compared to complex landscapes in which vineyards are surrounded by semi‐natural habitats. Similarly, insecticide applications doubled in vineyard‐dominated landscapes but declined in vineyards surrounded by shrubland. Importantly, pest population stochasticity would have masked these large effects if numbers of study sites and years were reduced to typical levels in landscape pest‐control studies. Our results suggest increasing landscape complexity may mitigate pest populations and insecticide applications. Habitat conservation represents an economically and environmentally sound approach for achieving sustainable grape production.     

Variation in the ribosomal internal transcribed spacers and 5.8S rDNA among five species of Acropora (Cnidaria; Scleractinia): patterns of variation consistent with reticulate evolution

The ITS sequences of Acropora spp. are the shortest so far identified in any metazoan and are among the shortest seen in eukaryotes; ITS1 was 70-80 bases, and ITS2 was 100-112 bases. The ITS sequences were also highly variable, but base composition and secondary structure prediction indicate that divergent sequence variants are unlikely to be pseudogenes. The pattern of variation was unusual in several other respects: (1) two distinct ITS2 types were detected in both A. hyacinthus and A. cytherea, species known to hybridize in vitro with high success rates, and a putative intermediate ITS2 form was also detected in A. cytherea; (2) A. valida was found to contain highly (29%) diverged ITS1 variants; and (3) A. longicyathus contained two distinct 5.8S rDNA types. These data are consistent with a reticulate evolutionary history for the genus Acropora.