Mutagenicity of cyanate, a decomposition product of MNU

Knox reported that the short-term effects of the carcinogen methylnitrosourea (MNU) were due to the formation of its decomposition product, the cyanate ion. He showed that cell survival and DNA synthesis decreased as the concentration of MNU and the cyanate ion (NCO-) increased in the medium. Further, the product of MNU decomposition comigrated with NCO- when added to his chromatographic test system. However, Knox did not study the mutagenicity of MNU or its breakdown products. We compared the mutagenicity of MNU and potassium cyanate (KNCO) in mammalian cells. Our results demonstrate that, although it is toxic to cells, KNCO does not induce ouabain-resistant mutants in cultured Chinese hamster cells (V79).     

Modulation of myelopoiesis by different bacterial cell-wall components: induction of colony-stimulating activity (by pure preparations, low-molecular-weight degradation products, and a synthetic low-molecular analog of bacterial cell-wall components) in vitro.

Chemically pure preparations of three structurally unrelated components of the cell wall of gram-negative bacteria (BCWC), lipid A, outer-membrane lipoprotein, and murein, were tested for lymphocyte mitogenicity and the ability to induce colony-stimulating activity (CSA) in various serum-free tissue-culture systems. All three components were B-cell mitogens and induced CSA in spleen-cell cultures. However, in lymphnode-cell cultures the concentrations of these agents required for either mitogenicity or CSA induction differed markedly. Moreover, in contrast to thymidine incorporation, CSA induction was not influenced by pre-irradiation of the cells. Conversely, after removal of phagocytic cells with the iron-magnet technique, CSA was no longer inducible by BCWC, while lymphocyte proliferation was barely impaired. All three BCWC readily induced CSA release in cultures of adherent peritoneal cells without influencing the release of a cytoplasmic enzyme. BCWC-dependent CSA release from adherent peritoneal cells was not influenced by pretratment of the cultures with anti-immunoglobulin, but completely suppressed by preincubation with anti-macrophage-1.2 alloantiserum and complement. CSA induction in macrophage cultures was also achieved with a low-molecular-weight synthetic muramyldipeptide and degradation products of lipoprotein. The results suggest that the induction of CSA is not directly related to the mitogenic, immunogenic, or antigenic properties of the BCWC, but that BCWC-mediated CSA production is caused by a direct “hormone-like” interaction of the agents with mature macrophages.     

Purification and partial characterization of citrate synthase from Phaseolus vulgaris mitochondria

Citrate synthase (E.C. 4.1.3.7) has been isolated from bean mitochondria by an improved procedure. The purified enzyme had a specific activity of 50. In most respects (e.g. sedimentation constant, K_ms, pH sensitivity and ionic strength inhibition) the enzyme is similar to that prepared from mammalian sources. The feature distinguishing the plant enzyme from the others was its inhibition by several sulfhydryl reagents. The substrates conferred either complete protection (acetyl coenzyme A) or partial protection (oxalacetic acid) against the inhibition. Dithiothreitol (DTT) was capable of partially reversing the inhibition. The efficacy of DTT varied with the sulfhydryl reagent and was inversely related to the period of incubation of the enzyme with the reagent.     

Tropical forest and mangrove history from southeastern Mexico: a 5000 yr pollen record and implications for sea level rise

A 250 cm long core from El Palmar, a swamp area located along the Rio Hondo river in the south of the Yucatan Peninsula, near the Belizean border, reveals the environmental history of the mangrove and tropical forest of the last 5000 years. The period between 5000 and 4600 b.p. shows sandy deposits, which form the early infill and development of the swamp. A medium-statured tropical forest covered the area and members of the Moraceae and Fabacaeae dominated this early forest. The period between 4600 and 4000 b.p. presents a clear change to a mangrove system with Conocarpus erecta and Rhizophora mangle as dominant trees. This vegetational change is due to flooding of the Rio Hondo river, which deposits sediments of high salinity due to higher sea-level. The medium-statured forest became established at some distance from the swamp area. After 4400 b.p. C. erecta appears as the dominant mangrove species and the R. mangle stands are less predominant in the area. The tropical forest was close to the swamp area and was mainly composed of members of the Moraceae, Arecaceae and Fabaceae as dominant taxa of this vegetational mosaic.     

New World Monkeys and Color

The visual worlds of most primates are rich with potential color signals, and many representatives of the order have evolved the biological mechanisms that allow them to exploit these sources of information. Unlike the catarrhines, platyrrhines typically have sex-linked polymorphic color vision that provides individuals with any of several distinct types of color vision, including both trichromatic and dichromatic variants. In recent years, this polymorphism has been the target of an expanding range of research efforts. As a result, researchers now reasonably understand the proximate biology underlying the polymorphisms, and a number of ideas have emerged as to their evolution. Progress has also been made in illuminating how color vision capacities may be related to the particular visual tasks that New World monkeys face.     

Evaluation of secondary infertility in the gorilla

Reproductive failure in two female gorillas in the Los Angeles Zoo led to evaluation for secondary infertility. Male factor was excluded by noting routine conceptions in other individuals in the same group, and by behavioral observations of coital activity with the infertile females. Biochemical evidence of ovarian function was obtained by urinary sex steroid analysis. Continuity of the reproductive tract of the infertile apes was then studied by hysterosalpingography and laparoscopy while their general health was evaluated by ultrasonography and physical examination. Progressive, multiorgan involvement with Echinococcus vogeli was documented and mebendazole therapy begun. The investigation of secondary infertility in great apes by combined methods is safe and accurate, but requires special equipment and experienced personnel.     

Inhibitory CD161 receptor identified in glioma-infiltrating T cells by single-cell analysis

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Immunogenetic and electrophoretic studies with extracts of different adult Culex pipiens strains

The results of an immunological and electrophoretical analysis of extracts of the three adult Culex pipiens strains Paris, Hamburg, and Oggelshausen are presented. The gel-diffusion technique has revealed five antigens which are common and identical in both male and female extracts of all three strains; the females have an additional antigenic component. By disk electrophoresis in acrylamide gel the extracts could be separated into 24 protein fractions common to both sexes and an additional female component. It can be assumed that the additional components found with both methods are identical.     

Untersuchungen über den Proteingehalt virusinfizierter Futtergräser

Unter Verwendung verschiedener Methoden der Inokulation wurde das Verhalten von acht Aprikosensorten sowie 18 Pflaumensorten bzw. -zuchtklonen gegenüber dem Plum pox virus (PPV) überprüft und verglichen. Die eingesetzten Methoden führten zu übereinstimmenden Ergebnissen in Hinblick auf Virusresistenz und -anfa¨lligkeit. Die einbezogenen Aprikosensorten entwickelten nach der Übertragung des PPV entweder chlorotische Blattflecken oder sie verhielten sich immun. Überempfindlichkeitsreaktionen waren nicht zu beobachten. Die geprüften Pflaumengenotypen reagierten auf eine Virusinfektion mit der Ausbildung chlorotischer und nekrotischer Symptome, die allein oder gemeinsam auftraten. Immunität lag in keinem Fall vor. Bei dem untersuchten Aprikosensortiment besteht offensichtlich keine Korrelation zwischen Virusisolat, dessen Stammzugehörigkeit (entsprechend den Ergebnissen der PCR) und Resistenzverhalten. Bei Pflaumen scheint der Einflu g des Virusisolates auf das Resistenzniveau grö g er zu sein.     

Latitudinal variation in blue tit and great tit nest characteristics indicates environmental adjustment

Aim The laying of eggs and the building of a nest structure to accommodate them are two of the defining characteristics of members of the class Aves. Nest structures vary considerably across avian taxa and for many species the structure of the completed nest can have important consequences both for parents and their offspring. While nest characteristics are expected to vary adaptively in response to environmental conditions, large‐scale spatial variation in nest characteristics has been largely overlooked. Here, we examine the effects of latitudinal variation in spring temperatures on nest characteristics, including insulatory properties, and reproductive success of blue tits, Cyanistes caeruleus, and great tits, Parus major. Location Great Britain. Methods Nests and reproductive data were collected from seven study sites, spread over 5° of latitude. The nest insulatory properties were then determined before the nests were separated into nest base material and cup lining material. Results As spring temperatures increased with decreasing latitude, the mass of the nest base material did not vary in either species, while the mass of the cup lining material and nest insulatory properties decreased in both species. This suggests that in response to increasing temperatures the breeding female reduces the mass of the cup lining material, thereby maintaining an appropriate microclimate for incubating and brooding. The mean first egg date of both species advanced with decreasing latitude and increasing spring temperatures, although clutch size and brood size at hatching and fledging did not vary. Main conclusions This is the first study to demonstrate that the nest‐construction behaviour of birds varies in response to large‐scale spatial variation in ambient temperatures. Therefore, nest composition reliably indicates environmental conditions and we suggest that studies of nest structure may be sentinels for the early signs of rapid climate change.