Distribution and cycling of C, N, Ca, Mg, K and P in three pristine, old-growth forests in the Cordillera de Piuchué, Chile

We assessed a number of biomass and soil parameters in order to examinerelationships among nutrient availability, forest productivity and vegetationpatterns in two old-growth forested watersheds in a pristine montane landscapeon Isla de Chiloé, Chile. We selected watersheds in both gymnosperm- andangiosperm-dominated forests and determined tree species, d.b.h. and health forall trees < 2 cm d.b.h. in plots established at 50m intervals. Soils were sampled at two depths in each plot andanalyzed for total C and N, and for exchangeable Ca, K, Mg andresin-extractableP. Allometric relationships and vegetation nutrient concentrations were used todetermine above-ground pools from the vegetation survey data. Growth rates werederived from increment core measures. Soil pools of most elements measuredappear adequate to support forest growth indefinitely. Mineralized nitrogen,which is similar in quantity to the annual demand for nitrogen from the soil isthe exception, consistent with the possibility of N limitation in two of theforest types studied. A third type, an evergreen broadleaved forest, appears torequire substantially more nitrogen than would appear to be available from netmineralization measurements. Productivity per unit of nitrogen required fromthesoil is quite high, largely as a consequence of the evergreen habit of thespecies in these forests. Compared to other temperate montane forests in theNorthern Hemisphere, nutrient pools and cycling characteristics were found tobemostly similar across forest types, in spite of considerable variation invegetation and soils.     

Chemolithoautotrophic Nitrifiers in the Phyllosphere of a Spruce Ecosystem Receiving High Atmospheric Nitrogen Input

Evidence is presented for the first time that chemolithoautotrophic ammonia oxidizers (CAO) and chemolithoautotrophic nitrite oxidizers (CNO) colonize in appreciable cell numbers the phyllosphere of spruce trees in a forest ecosystem exposed for decades to high levels of atmospheric nitrogen (The Höglwald Forest, Bavaria, Germany). The results strongly indicate that both, CAO and CNO are predominantely located inside the spruce needles, most likely within the stomatal cavity. These results are further supported by field experiments of NH₃ uptake into twigs on intact spruce trees in the presence and absence of 10 Pa acetylene, an inhibitor of the ammonia monooxygenase of CAO. It is clearly demonstrated for the first time that in situ uptake of NH₃ from the atmosphere into spruce needles exposed to high levels of atmospheric N is not catalyzed exclusively by the tree, but is the result of combined activities of both, the spruce trees and the chemolithoautotrophic nitrifiers colonizing the needles.     

The Californian urban butterfly fauna is dependent on alien plants

Abstract. Using the unusually well-documented butterfly fauna of Davis, Yolo County, California, it is shown that the mainly native species commonly observed in gardens breed mostly or entirely on alien plants, especially naturalized weeds. Over 40% of the fauna has no known native hosts in the urban–suburban environment. Were certain alien weeds to be eradicated or their abundance greatly reduced, the urban-suburban butterfly fauna would disappear. This might be regarded as an unfortunate, and perhaps intolerable, side-effect of such programs.     

Pollination and phenology of flowers in the canopy of two contrasting rain forest types in Amazonia,Colombia

The main objective of this investigation was to study the pollination characteristics of two types of Amazonian rain forest at plant community level. Seasonally inundated forest was compared with upland (tierra firme) forest. The study focused on plant species in the canopy. The pollination spectra show that in both forests most canopy trees and lianas are pollinated by small bees, large bees, butterflies or by small, relatively unspecialized insects. In the upland forest small bees are the most important pollinators (32% of all species of trees and lianas are pollinated by them), whereas large bees are predominant in the floodplain (22%). Other pollinators, like hummingbirds, bats, moths, and beetles are less common (>10%), but always somewhat more important in the flood plain than in the upland forest. Bees are the most common pollinators of epiphytes. In the flood plain forest, flies are also important as epiphyte pollinators (19%), whereas in the upland forest hummingbirds pollinate more epiphytes. The phenological patterns are quite similar in both the upland and the flood plain. We found a peak in flowering in the transition period between the wet and the dry season. Flowering activity was lowest during the wet season. Differentiation in sexual systems was correlated with life form. Dioecy and monoecy were found mostly among tree species. Most species of all life forms though were hermaphroditic. No difference with respect to the relative importance of sexual systems was found between the two forest types.     

Differences in Composition and Mucosal Adhesion of Bifidobacteria Isolated from Healthy Adults and Healthy Seniors

Fifty-one Bifidobacterium strains were isolated from the feces of healthy adults (30–40 years old) and seniors (older than 70 years of age). B. adolescentis, B. breve, B. infantis, and B. longum were isolated from the healthy adults and B. adolescentis and B. longum from elderly subjects. The tested bacteria bound, in vitro, to intestinal mucus in a strain dependent manner. The strains isolated from healthy adults, and especially B. adolescentis, bound better to intestinal mucus than those isolated from seniors. These results indicate that the mucosal adhesive properties of the human Bifidobacterium flora were reduced with the aging of the host. This shift to a Bifidobacterium flora with reduced adhesive abilities may explain the decrease in bifidobacteria levels in the intestinal microflora of aging people. Received: 7 February 2001 / Accepted: 3 April 2001     

Assignment of 64 genes expressed in 28-day-old pig embryo to radiation hybrid map

A swine resource family was constructed at the National Institute of Animal Industry, Japan, in order to determine the genetic regions responsible for economically important traits, including fetus development. To identify genes expressed in the early stage of embryo development, we cataloged and mapped genes expressed in a 28-day-old normal pig embryo. In this effort, we have mapped 64 genes, which have map information in human genome onto a swine radiation hybrid (RH) map, IMpRH. These mappings provided additional chromosomal homologies between swine and human to improve the comparative map between the two species. The distribution of the genes assigned to swine chromosomes are as follows: 9 genes were assigned on SSC6; 6 genes each assigned on SSC5 and SSC14; 5 genes each assigned on SSC3, SSC4, and SSC8; 4 genes each assigned on SSC1, SSC7, SSC9, and SSC15; 3 genes each assigned on SSC2, SSC13 and SSCX; and 1 gene each assigned on SSC10, SSC11, and SSC16. Moreover, the present findings revealed 18 new chromosomal homologies between pig and human. Briefly, SSC3 regions were indicated to correspond with HSA1 and HSA10; SSC4 with HSA6; SSC5 with HSA2, HSA15, and HSA16; SSC6 with HSA3, HSA6, and HSA20; SSC7 with HSA11; SSC8 with HSA3, HSA6, and HSA7; SSC9 with HSA8; SSC13 with HSA1; SSC14 with HSA13; SSC15 with HSA19; SSC16 with HSA9. Received: 19 December 2000 / Accepted: 13 March 2001     

The effect of chronically ingested inorganic lead on brain levels of Fe,Zn, Cu,and Mn of 25 day old rat

Lead poisoning was produced in suckling rats by lead fed to lactating mother rats being transmitted to newborns $\text{via}$ maternal milk. The brain of 25 day old lead poisoned rats contained 6.0 to 12.5 ppm lead. Zinc was depressed 56% (cerebral cortex), 45% in cerebellum and 43% (caudate nucleus) whereas copper was depressed 52% in the cerebellum. Inhibition of monoamine oxidase (pargyline) or partial depletion of serotonin and norepinephrine did not alter the concentration of Fe, Cu, Zn, or Mn in brain.