Primary forests are irreplaceable for sustaining tropical biodiversity

Human-driven land-use changes increasingly threaten biodiversity, particularly in tropical forests where both species diversity and human pressures on natural environments are high. The rapid conversion of tropical forests for agriculture, timber production and other uses has generated vast, human-dominated landscapes with potentially dire consequences for tropical biodiversity. Today, few truly undisturbed tropical forests exist, whereas those degraded by repeated logging and fires, as well as secondary and plantation forests, are rapidly expanding. Here we provide a global assessment of the impact of disturbance and land conversion on biodiversity in tropical forests using a meta-analysis of 138 studies. We analysed 2,220 pairwise comparisons of biodiversity values in primary forests (with little or no human disturbance) and disturbed forests. We found that biodiversity values were substantially lower in degraded forests, but that this varied considerably by geographic region, taxonomic group, ecological metric and disturbance type. Even after partly accounting for confounding colonization and succession effects due to the composition of surrounding habitats, isolation and time since disturbance, we find that most forms of forest degradation have an overwhelmingly detrimental effect on tropical biodiversity. Our results clearly indicate that when it comes to maintaining tropical biodiversity, there is no substitute for primary forests.     

De novo cardiomyocytes from within the activated adult heart after injury

A significant bottleneck in cardiovascular regenerative medicine is the identification of a viable source of stem/progenitor cells that could contribute new muscle after ischaemic heart disease and acute myocardial infarction. A therapeutic ideal--relative to cell transplantation--would be to stimulate a resident source, thus avoiding the caveats of limited graft survival, restricted homing to the site of injury and host immune rejection. Here we demonstrate in mice that the adult heart contains a resident stem or progenitor cell population, which has the potential to contribute bona fide terminally differentiated cardiomyocytes after myocardial infarction. We reveal a novel genetic label of the activated adult progenitors via re-expression of a key embryonic epicardial gene, Wilm's tumour 1 (Wt1), through priming by thymosin β4, a peptide previously shown to restore vascular potential to adult epicardium-derived progenitor cells with injury. Cumulative evidence indicates an epicardial origin of the progenitor population, and embryonic reprogramming results in the mobilization of this population and concomitant differentiation to give rise to de novo cardiomyocytes. Cell transplantation confirmed a progenitor source and chromosome painting of labelled donor cells revealed transdifferentiation to a myocyte fate in the absence of cell fusion. Derived cardiomyocytes are shown here to structurally and functionally integrate with resident muscle; as such, stimulation of this adult progenitor pool represents a significant step towards resident-cell-based therapy in human ischaemic heart disease.     

Guest Editorial:Special Issue on Visualization and Computer Graphics

In the decade of data explosion, a significant challenge is how to transform data into understandings and insights that are useful to people. Visualization,the use of computer-supported, interactive visual     

Foods and weights of the Rock Ptarmigan on Amchitka, Aleutian Islands, Alaska

We examined the crop contents from 129 Rock Ptarmigan ( Lagopus mutus ) collected between 1967 and1971 on Amchitka, Aleutian Islands, Alaska. On a yearly basis two plant species, Empetrum nigrum and Equisetum arvense , made up 87% of the diet. Only in July and August were they less than 90% of the diet, and in those months they constituted 65% of the diet. During the warmer months (May-October) when a variety of plant species were available, the Amchitka ptarmigan fed upon growth forms of plants high in nutritive value (particularly Equisetum strobili ). Its main winter food was the vegetative portions of Empetrum , one of the few abundant evergreen vascular plants on the island.     

Relationships of aspen ( Populus tremuloides ) to foraging patterns of beaver ( Castor canadensis ) in the Strawberry Valley of central Utah

Eight study sites were examined in Strawberry Valley, Utah, to assess the response of aspen ( Populus tremuloides Michx.) to cutting activities of beaver ( Castor Canadensis Warren & Hall) and to determine patterns by which the animals utilize aspen stands. Sites utilized by beaver, along with adjacent control plots in mature, uncut aspen stands, were sampled. Age-class profiles of control plots were composed of a broad age distribution with trees ranging from 3 to 108 years old. Age-class profiles for aspen sprouts in areas previously used by beavers were composed of trees averaging seven years of age with a range of 1 to 24 years. Age distribution of sprouts in areas used by beaver show a tendency to be skewed toward younger age classes. Average density of aspen in areas used by beaver was 15,800stems per hectare compared to 2,980 stems per hectare in controls. Stump densities in use areas ranged from 900 to 5,066 stems per hectare. Densities of stumps in the 0-5-cm size class were greater in areas used by beavers than in the corresponding size class in the mature forests. A regression equation describing age versus diameter relationships was calculated using data from 312 aspen trees. Total phenolics and mineral nutrients in the twigs and bark of mature aspen trees and aspen sprouts were also examined to determine if variations could explain foraging patterns of beaver in the valley. Total phenolics were highly variable between sampling groups, and differences were not significant. Twigs from mature aspen and aspen sprouts were significantly higher in nitrogen, phosphorus, and iron. Zinc was significantly higher in the bark of mature aspen trees and twigs of aspen sprouts. Calcium concentrations were significantly higher in mature aspen bark, and magnesium was significantly higher in mature aspen twigs.     

Chloroplast ultrastructure in the desert shrub Chrysothamnus nauseosus ssp. albicaulis

Ultrastructure of the chloroplasts of white rubber rabbitbrush ( Chrysothamnus nauseosus (Pallas) Britt. ssp. albicaulis ) was observed with electron microscopy. In addition, leaf anatomy was observed with light microscopy. Previously, it had been reported that the leaves of this desert shrub exhibited a relatively high rate of photosynthesis when compared to other C 3 plants. Comparisons with chloroplasts of other C 3 and C 4 plants demonstrated a reduced amount of granal stacking in the rabbitbrush. However, the classification of rabbitbrush as a C 3 plant is confirmed. RUBP-carboxylase concentration is reported at about 450 mg · ml -1 stromal space based on the estimation of 1 mg of chlorophyll per 25 ul of stromal space in a normal C 3 chloroplast and data from an assay to determine the ratio of RUBP-carboxylase to chlorophyll.     

Coleoptera of the Idaho National Engineering Laboratory: an annotated checklist

An insect survey was conducted on the Idaho National Engineering Laboratory during the summers of 1981–1983. This site is on the Snake River Plains in southeastern Idaho. Presented here is an annotated checklist of the Coleoptera collected. Successful collecting methods, dates of adult occurrence, and relative abundance are given for each species. Relevant biological information is also presented for some species.     

Vegetation patterns in relation to slope position in the Castle Cliffs area of southern Utah

Vegetation patterns in relation to slope position were studied on four foothill knolls in the Castle Cliffs area of Washington County, Utah. Study plots were established at four different slope positions: ridge top, upper slope, lower slope, and floodplain. Exposed rock was highest on the ridge top; exposed soil was highest on the floodplain; soil depth increased downslope. Plant life form varied with respect to slope position. Grass, annuals, and cryptogamic crust cover was highest on the ridge top and shrubs were most prominent on the midslope. Forb cover gradually increased downslope. Succulents were restricted to the ridge top or floodplain. Species distribution was distinct and strongly correlated to slope position. Two sets of congeneric species showed strong patterns of niche separation. The vegetation of the slopes is highly distinct at the ridge top and floodplain and grades toward the midslope from both ends.