Further Studies of Breeding Restrictions among Crypthecodinium cohnii-like Dinoflagellates. Evidence of a New Interbreeding Group

SYNOPSIS. Studies on sexual compatibility among populations of different origins of axenically cultivated, heterotrophic, homothallic dinoflagellates resembling Crypthecodinium cohnii have been undertaken using motility mutants and complementation testing. We showed previously that one interbreeding group or biologic species can be found on the East and West coasts of the United States, thus far associated only with Fucus. In addition, we found several strains of these organisms each of which, though fertile in intrastrain crosses, appeared infertile with all other isolates. A continuation of these studies has revealed another biologic species of wide geographic distribution (Taiwan, California, Florida, New York) and apparently associated with sea weeds other than Fucus.     

Varying Kinetoplast Ultrastructure in Two Subspecies of Herpetomonas muscarum (Leidy)*

SYNOPSIS. The kinetoplast nucleoid of Herpetomonas muscarum muscarum is a disk-shaped mass of filaments with sharply delimited anterior and posterior margins. The kinetoplast nucleoid of Herpetomonas muscarum ingenoplastis is elongate, tapered, and made up of long, helically arranged filaments. Possible explanations of these structures on the basis of work by others on isolated kinetoplast DNA are given. The double flagellum of Herpetomonas is seen by electron microscope to be two complete flagella in close contact but with no visible connection to each other.     

THE EFFECT OF SUCROSE SPRAYING ON SYMPTOMS CAUSED BY BEET YELLOWS VIRUS IN SUGAR BEET

When leaves of sugar-beet plants infected with beet yellows virus were sprayed daily with 10% sucrose solution, yellowing symptoms were intensified. When glasshouse plants were shaded so that the light intensity was reduced to less than half of full daylight, yellowing symptoms were suppressed more completely on un-sprayed than on sprayed plants. Spraying with 2–5 % sucrose solution had similar, but slightly smaller effects.
Spraying with sucrose solution increased the carbohydrate content of the leaves, and the effects on symptom intensity and carbohydrate content were closely correlated. The regression coefficients of symptom score on total sugar content were nearly the same for shaded and unshaded plants. As the severity of symptoms was increased by supplying carbohydrate without change in the light conditions, it is concluded that light intensity affects symptom expression by varying the carbohydrate content of the leaves through its influence on photosynthesis.
Sucrose spraying increased the yield of roots of healthy and infected plants, and most of the increase was sucrose. This shows that sprayed sugar was translocated to the roots from the leaves of both healthy and infected plants.
Measurements of changes in carbohydrate content between evening and morning samplings confirmed that movement of carbohydrate out of infected leaves is not stopped by infection.     

Social Organisation in an Enclosed Group of Red Deer (Cervus elaphus L.) on Rhum

Primate social organisation is often considered to be more complex than that of ‘lower’ mammals. The dominance hierarchy, which is given especial emphasis in most studies of social species, has been criticised on the grounds that rank is poorly related to other aspects of social organisation. These two ideas were investigated in an enclosed group of red deer by looking at the relationships between four aspects of social organisation: the dominance hierarchy; social grooming behaviour; non-copulatory mounting behaviour; spatial organisation. The last three aspects have frequently been studied in primates, but rarely in ungulates.     

STUDIES ON THE FEEDING OF MYZUS PERSICAE (SULZ.) ON RADIOACTIVE PLANTS

Adult apterae of Myzus persicae (Sulz.), were fed, after a period of fasting, on leaves containing radioactive phosphorus. The weight of sap imbibed by the aphids after varying feeding times was estimated by relating their radioactivity, at the end of each feeding period, to the activity per unit fresh weight of the leaf lamina on which they fed. The calculations were made on the assumption that ³²P is uniformly distributed in the leaf tissues.
The mean rates of uptake so estimated were about 10 μg. of sap for the first hour of feeding; 40 μg/hr. between 1 and 4 hr. feeding, and 17 μg./hr. between 6 and 24 hr. feeding. The decrease in apparent rate of uptake with the longer feeding times is attributed to loss of ³²P in nymphs born during the feeding period.
When aphids were fed on seedlings raised in water culture solution containing ³²P no activity was detected after 5 min. feeding and an insignificant fraction after 15 min., but when the isotope was introduced by immersing the leaves for several days in the culture solution, aphids fed for 5 and 15 min. became appreciably active.
The increase in rate of uptake after 1 hr. of feeding indicates that aphids do not start to feed normally until they reach the phloem, but the activity after short feeding times suggests that previously starved aphids feed to some extent on other tissues, possibly only on the epidermis.     

Mutant p21ras in vinyl chloride exposed workers

The production of mutations in cellular oncogenes such as ras is involved in the development of many human cancers. These mutations result in the expression of mutant forms of the encoded p21 protein which can potentially serve as a biomarker for this carcinogenic process. Workers exposed to vinyl chloride (VC) who are at risk for the development of the sentinel neoplasm angiosarcoma of the liver (ASL) represent a model population for the study of such a mutant p21ras biomarker, since VC is known to cause a specific ras mutation in ASL. In order to determine the relationship between VC exposure and this biomarker, serum samples from a cohort of 225 French VC workers and 111 age-sex-race-smoking-drinking matched unexposed controls were examined for the presence of mutant p21ras by immunoblotting with a mouse monoclonal antibody specific for the mutant protein. Stratifying the exposed workers by degree of VC exposure in estimated ppm-years by quartiles yielded a statistically significant trend for increasing odds ratio for sero-positivity of the p21ras biomarker with increasing exposure. These results suggest that this serum biomarker is related to VC exposure and may be an early indicator of carcinogenic risk in exposed individuals.     

Woody biomass production during the second rotation of a bio-energy Populus plantation increases in a future high CO2 world

The quickly rising atmospheric carbon dioxide (CO₂)‐levels, justify the need to explore all carbon (C) sequestration possibilities that might mitigate the current CO₂ increase. Here, we report the likely impact of future increases in atmospheric CO₂ on woody biomass production of three poplar species (Populus alba L. clone 2AS‐11, Populus nigra L. clone Jean Pourtet and Populus×euramericana clone I‐214). Trees were growing in a high‐density coppice plantation during the second rotation (i.e., regrowth after coppice; 2002–2004; POPFACE/EUROFACE). Six plots were studied, half of which were continuously fumigated with CO₂ (FACE; free air carbon dioxide enrichment of 550 ppm). Half of each plot was fertilized to study the interaction between CO₂ and nutrient fertilization. At the end of the second rotation, selective above‐ and belowground harvests were performed to estimate the productivity of this bio‐energy plantation. Fertilization did not affect growth of the poplar trees, which was likely because of the high rates of fertilization during the previous agricultural land use. In contrast, elevated CO₂ enhanced biomass production by up to 29%, and this stimulation did not differ between above‐ and belowground parts. The increased initial stump size resulting from elevated CO₂ during the first rotation (1999–2001) could not solely explain the observed final biomass increase. The larger leaf area index after canopy closure and the absence of any major photosynthetic acclimation after 6 years of fumigation caused the sustained CO₂‐induced biomass increase after coppice. These results suggest that, under future CO₂ concentrations, managed poplar coppice systems may exhibit higher potential for C sequestration and, thus, help mitigate climate change when used as a source of C‐neutral energy.