Transmission of Megatrypanum Trypanosomes to Cervus dama by Tabanidae1

Four fallow deer, Cervus dama, became infected with Trypanosoma (Megatrypanum) sp. by oral application of triturated guts from tabanids collected in an area with deer but without any cattle; four control calves remained negative. Upon challenge with triturated guts from tabanids from an area with pastured cattle, the four calves became infected with Trypanosoma (M.) theileri. The prepatent period in deer was five days or less. Haematopota spp. and Tabanus spp. were identified as vectors of the deer trypanosomes. It is concluded that the trypanosomes of C. dama belong to a Megatrypanum species that is not identical with T. theileri.     

Effects of Na2SO4, K2SO4 and KCl on Growth and Ion Uptake of Callus Cultures of Vaccinium corymbosum L. cv. Blue Crop

Non-selected and Na₂SO-, K₂SO₄- or KCl-selected callus culturesof Vaccinium corymbosum L. cv. Blue Crop were grown on mediasupplemented with 0, 25 and 50 mM Na₂SO₄ (non-selected and Na₂SO(-selectedonly), 0, 25 and 50mMK₂SO₄ (non-selected and K₂SO₄-selectedonly) or 0, 50 and 100 mM KCl (non-selected and KCl-selectedonly). On all media, growth of selected callus (on a fresh-weightor dry-weight basis) was greater than that of non-selected callus,and selected callus grew optimally on the level and type ofsalt on which it was selected. Selected callus was friable andmaintained a higher f. wt:d. wt ratio. Tissue water potentialin selected callus was more negative than in non-selected callus. Flame photometry and chloridometry showed Na⁺, K⁺ and Cl^–accumulated in callus to concentrations equal to or greaterthan the initial concentration in the medium. Turbidometry showedthat tissue SO₄^2- concentration was lower than the concentrationin the medium. In most cases selected callus accumulated moreNa⁺, K^sup, SO₄^2– or Cl^– than non-selected callus.Vacuolar ion concentration was measured by electronprobe X-raymicroanalysis, and on most media selected callus had highervacuolar ion concentrations than non-selected callus. SO₄^2–and Cl^– were accumulated in the vacuoles at concentrationshigher than the external medium, but vacuolar Na⁺ concentrationdid not reach external concentration on Na₂SO₄ and on potassiumsalts was maintained between 12 and 17 mM. Vacuolar K⁺ concentration(approx. 142–191 mM on no salt) decreased on Na₂SO₄ andincreased on K₂SO₄ and KCl. There was no precise correlation between total or specific ionaccumulation (Na⁺, K⁺, SO₄^2– and Cl^– and fresh-weightyield. Results suggest that selection results in adaptationin response to decreased water potential of the medium. Vaccinium corymbosum, blueberry, electronprobe X-ray microanalysis, callus, in vitro selection, salt tolerance, KCl, K₂SO₄, Na₂SO₄     

Interaction of pheromones during food exploitation by the termite Schedorhinotermes lamanianus

Abstract. Chemical signals from secretions of different exocrine glands modulate a variety of behavioural patterns in termite societies. These signals have multiple functions and may be interactive. During food exploitation workers of the African termite Schedorhinotermes lamanianus (Isoptera: Rhinotermitidae) employ, on foraging trails, the secretion from the sternal gland both for orientation and recruitment to a food source. The secretion from the labial gland, released onto the food by gnawing termites, stimulates additional workers to gnaw at the same site, thereby forming aggregations of gnawing termites. An interaction between these two pheromones during food exploitation is demonstrated for the first time. The volatile signal from the sternal gland inhibits in a dose-dependent manner the non-volatile, highly persistent, signal from the labial gland. The development of gnawing aggregations is inhibited and established ones are dissolved. Behavioural evidence for the perception of both the volatile signal from the sternal gland by olfactory neurones and of the non-volatile signal from the labial gland by gustatory neurones on the antennae is given. The interaction of the two pheromones as a basis for the development of distinct commuting and gnawing zones on the food source, and as a means for a dynamic regulation of food exploitation, is discussed.     

Late Pliocene vegetation and climate of Zhangcun region,Shanxi, North China

To understand the Neogene climatic changes in eastern Asia and evaluate the intercontinental climatic differences, we have quantitatively reconstructed the vegetation successions and climatic changes in the late Pliocene Zhangcun area based on the palynological data and explored the regional climatic differences between central Europe and eastern Asia. The late Pliocene palynological assemblage of Zhangcun, Shanxi was composed of 63 palynomorphs, belonging to 50 families, covering angiosperms (90.2%), gymnosperms (9.7%), ferns (0.09%), and other elements (0.02%). Four periods of vegetation succession over time were recognized. In period 1, a needle‐ and broad‐leaved mixed forest prevailed with a cool and dry climate. Period 2 was characterized by an expansion of forest with a warmer and wetter climate. The number of conifers increased and that of herbs decreased in period 3, and the climate became cool and dry. In period 4, the forest was dominated by conifers and reflecting a cooler climate. The data of seven climatic parameters in general and four periods estimated by the Coexistence Approach suggested that (1) The late Pliocene temperatures and precipitations were higher than today. (2) The Neogene climate of both Central Europe and North China exhibited a general cooling and drying trend although the mean annual temperature dropped by ca. 1 °C in North China, vs. ca. 7 °C in Central Europe from the middle Miocene to the late Pliocene. (3) The decline of the mean maximum monthly precipitation might signal a weakening of the summer monsoon. (4) The decline of both the mean coldest monthly temperature and the mean minimum monthly precipitation might be linked to the strengthening of the winter monsoon in eastern Asia. (5) The rapid uplift of the Tibetan Plateau strengthened the climatic cooling and drying during the late Pliocene of the Zhangcun region.