ALBERT

Notizen: Abstract  Regenerating forests have become a common land-cover type throughout the Brazilian Amazon. However, the potential for these systems to accumulate and store C and nutrients, and the fluxes resulting from them when they are cut, burned, and converted back to croplands and pastures have not been well quantified. In this study, we quantified pre- and post-fire pools of biomass, C, and nutrients, as well as the emissions of those elements, at a series of second- and third-growth forests located in the states of Pará and Rondônia, Brazil. Total aboveground biomass (TAGB) of second- and third-growth forests averaged 134 and 91 Mg ha–1, respectively. Rates of aboveground biomass accumulation were rapid in these systems, but were not significantly different between second- and third-growth forests, ranging from 9 to 16 Mg ha–1 year–1. Residual pools of biomass originating from primary forest vegetation accounted for large portions of TAGB in both forest types and were primarily responsible for TAGB differences between the two forest types. In second-growth forests this pool (82 Mg ha–1) represented 58% of TAGB, and in third-growth forests (40 Mg ha–1) it represented 40% of TAGB. Amounts of TAGB consumed by burning of second- and third-growth forests averaged 70 and 53 Mg ha–1, respectively. Aboveground pre-fire pools in second- and third-growth forests averaged 67 and 45 Mg C ha–1, 821 and 707 kg N ha–1, 441 and 341 kg P ha–1, and 46 and 27 kg Ca ha–1, respectively. While pre-fire pools of C, N, S and K were not significantly different between second- and third-growth forests, pools of both P and Ca were significantly higher in second-growth forests. This suggests that increasing land use has a negative impact on these elemental pools. Site losses of elements resulting from slashing and burning these sites were highly variable: losses of C ranged from 20 to 47 Mg ha–1; N losses ranged from 306 to 709 kg ha–1; Ca losses ranged from 10 to 145 kg ha–1; and P losses ranged from 2 to 20 kg ha–1. Elemental losses were controlled to a large extent by the relative distribution of elemental mass within biomass components of varying susceptibilities to combustion and the temperatures of volatilization of each element. Due to a relatively low temperature of volatilization and its concentration in highly combustible biomass pools, site losses of N averaged 70% of total pre-fire pools. In contrast, site losses of P and Ca resulting from burning were 33 and 20% of total pre-fire pools, respectively, as much of the mass of those elements was deposited on site as ash. Pre- and post-fire biomass and elemental pools of second- and third-growth forests, as well as the emissions from those systems, were intermediate between those of primary forests and pastures in the Brazilian Amazon. Overall, regenerating forests have the capacity to act as either large terrestrial sinks or sources of C and nutrients, depending on the course of land-use patterns within the Brazilian Amazon. Combining remote sensing techniques with field measures of aboveground C accumulation in regenerating forests and C fluxes from those forests when they are cut and burned, we estimate that during 1990–1991 roughly 104 Tg of C was accumulated by regenerating forests across the Brazilian Amazon. Further, we estimate that approximately 103 Tg of C was lost via the cutting and burning of regenerating forests across the Brazilian Amazon during this same period. Since average C accumulations (5.5 Mg ha–1 year–1) in regenerating forests were 19% of the C lost when such forests are cut and burned (29.3 Mg ha–1), our results suggest that when less than 19% of the total area accounted for by secondary forests is cut and burned in a given year, those forests will be net accumulators of C during that year. Conversely, when more than 19% of regenerating forests are burned, those forests will be a net source of C to the atmosphere.

Notizen: Abstract  Numerous hypotheses have been proposed for the commonly observed, positive relationship between local abundance and geographic distribution in groups of closely related species. Here I consider how hostplant specialization and abundance affect the relative abundance and distribution of lycaenid butterflies (Lepidoptera: Lycaenidae). I first discuss three components of specialization: local specialization, turnover of specialization across a species’ range, and the minimum number of resources (or habitats) required by a species. Within this framework, I then consider one dimension of a lycaenid species’ niche, larval hostplant specialization. In a subalpine region of Colorado, I surveyed 11 lycaenid species and their hostplants at 17 sites. I compare this local information to continental hostplant use and large-scale distributions of the lycaenids and their hostplants. Local abundance of a lycaenid species is positively correlated with its local distribution (the number of sites occupied), but not with its regional or continental distribution. Neither local specialization (the number of hostplants used within one habitat) nor continental specialization (the number of hostplants used across many habitats) is correlated with local lycaenid abundance. Continental specialization is positively correlated with a species’ continental distribution, however. Finally, while generalist butterflies tend to have more hostplant available to them, differences in resource availability do not explain the differences in butterfly abundance. Although local abundance is correlated only with local distribution, I suggest that abundance-distribution relationships might emerge at regional and continental scales if local abundance were averaged across many habitat types. Consideration of the scale of a species’ resource specialization (within or among habitats) appears to be key to understanding the relationships between resource specialization, resource availability, and a species’ abundance and distribution.

Notizen: Abstract. The collagen type Iα1 Sp1 (ColIA1) polymorphism has been associated with reduced bone mineral density (BMD) and increased prevalence of osteoporosis. This study examines associations of the ColIA1 genotype with BMD and 5-year rates of change in BMD in elderly men and women. The 243 subjects, aged 65 years and older, were participants in two consecutive studies lasting a total of 5-years. BMD of the total body, femoral neck, and lumbar spine were made by dual-energy X-ray absorptiometry (DXA). The distribution of the genotypes (155 in the SS genotype, 79 in Ss, and 9 in ss) was proportionately similar to those reported by others. Baseline BMD did not differ significantly at any skeletal site. Unadjusted 5-year percent changes in BMD differed significantly by genotype only at the total body (P= 0.009), where the change was −0.29 ± 0.21 (SEM) in the SS genotype, −0.60 ± 0.25 in the Ss genotype, and −3.01 ± 0.72 in the ss genotype. This 9.4% increase in bone loss of the ss genotype relative to the SS genotype was reduced to an 8.9% increase after adjustment for sex, age, weight, and supplementation group. Results at the femoral neck were directionally similar, but not statistically significant. No effect of genotype on change in spine BMD was observed. In conclusion, bone loss from the total body was significantly greater in elderly men and women who were homozygous for the s allele compared with heterozygotes and SS homozygotes. This finding suggests a possible explanation for the association of the ColIA1 polymorphism with increased rates of osteoporotic fracture, but should be interpreted with caution because of the small number of subjects in the unfavorable ss genotype.

Notizen: Abstract. Men and women (n = 518) receiving moderate-to-high doses of corticosteroids were enrolled in two studies with similar protocols and randomly assigned to receive either placebo or risedronate (2.5 or 5 mg) for 1 year. All patients received daily calcium supplementation (500–1000 mg), and most also received supplemental vitamin D (400 IU). The primary endpoint was the difference between the placebo and active groups in lumbar spine bone mineral density (BMD) at 1 year; changes in BMD at other sites, biochemical markers of bone turnover, and the incidence of vertebral fractures were also assessed. In the overall population, the mean (SE) lumbar spine BMD increased 1.9 ± 0.38% from baseline in the risedronate 5 mg group (P 〈 0.001) and decreased 1.0 ± 0.4% in the placebo group (P= 0.005). BMD at the femoral neck, trochanter, and distal radius increased or was maintained with risedronate 5 mg treatment, but decreased in the placebo group. Midshaft radius BMD did not change significantly in either treatment group. The difference in BMD between the risedronate 5 mg and placebo groups was significant at all skeletal sites (P 〈 0.05) except the midshaft radius at 1 year. The 2.5 mg dose also had a positive effect on BMD, although of a lesser magnitude than that seen with risedronate 5 mg. A significant reduction of 70% in vertebral fracture risk was observed in the risedronate 5 mg group compared with the placebo group (P= 0.01). Risedronate was efficacious in both men and women, irrespective of underlying disease and duration of corticosteroid therapy, and had a favorable safety profile, with a similar incidence of upper gastrointestinal adverse events in the placebo and active treatment groups. Daily treatment with risedronate 5 mg significantly increases BMD and decreases vertebral fracture risk in patients receiving moderate-to-high doses of corticosteroid therapy.

Notizen: Abstract A high total pneumocandin titer (B0 + C0) with a low percentage of the structural isomer pneumocandin C0 was achieved by carrying out fermentations of Glarea lozoyensis at a high residual fructose concentration (125 g/l initial). When the fermentation was carried out at a low residual fructose concentration (40 g/l initial), pneumocandin production increased by 34%. However, a disproportionate increase in the level of pneumocandin C0 synthesized (250% increase vs 30% increase for pneumocandin B0) was observed. Midcycle addition of 150 mM NaCl or 116 mM Na2SO4 to low residual fructose fermentations returned the titer and isomer levels to those seen for the high residual fructose fermentation. The increase in pneumocandin C0 synthesis under low residual fructose conditions appears to be linked to the increase in the synthesis of trans-4 hydroxyproline, with the synthesis of trans-3 hydroxyproline remaining unaffected. This suggests that the formation of pneumocandin C0 is the result of a misincorporation of trans-4 hydroxyproline instead of trans-3 hydroxyproline by the pneumocandin peptide synthetase, and that the amount of trans-4 hydroxyproline formed dictates the frequency of this misincorporation.

Notizen: Abstract. Despite the identification of an increasing number of genes involved in sex determination and differentiation, no cause can be attributed to most cases of 46, XY gonadal dysgenesis, approximately 20% of 46, XX males and the majority of subjects with 46, XX true hermaphroditism. Perhaps the most interesting candidate for involvement in sexual development is SOX3, which belongs to the same family of proteins (SOX) as SRY and SOX9, both of which are involved in testis differentiation. As SOX3 is the most likely evolutionary precursor to SRY, it has been proposed that it has retained a role in testis differentiation. Therefore, we screened the coding region and the 5’ and 3’ flanking region of the SOX3 gene for mutations by means of single-stranded conformation polymorphism and heteroduplex analysis in eight subjects with 46, XX sex reversal (SRY negative) and 25 subjects with 46, XY gonadal dysgenesis. Although no mutations were identified, a nucleotide polymorphism (1056C/T) and a unique synonymous nucleotide change (1182A/C) were detected in a subject with 46, XY gonadal dysgenesis. The single nucleotide polymorphism had a heterozygosity rate of 5.1% (in a control population) and may prove useful for future X-inactivation studies. The absence of SOX3 mutations in these patients suggests that SOX3 is not a cause of abnormal male sexual development and might not be involved in testis differentiation.

Notizen: Abstract. The monoclonal antibody 5HL-5D11-D10 to antigen D10 identifies a cell lineage that is restricted to certain tissues of the human foregut. We investigated the tissue distribution of antigen D10 in mammals, birds, reptiles, amphibians and fish by immunohistochemical staining. Tissue from human and each of ten other mammalian species showed staining of gastric mucous neck cells and glands of the cardia and antrum, Brunner's glands, peribiliary glands and periductal glands of the pancreas. Six of the mammalian species also expressed antigen D10 in mucosa of the larger bronchi, and five expressed it to varying degree in small bowel distal to the duodenum and in colon (three of these five species). Antigen was not detected in any of the three species of bird studied. Both reptiles and amphibians showed strong staining for antigen D10 in the gastric mucous neck cells and pyloric glands, and in a subpopulation of secretory cells in the oesophagus, with the amphibian also expressing antigen in some epithelial cells of the mouth and lung. Although absent from two species of bony fish, antigen D10 was expressed by small groups of epithelial cells of the intestine of a shark, and generally by the epithelial and connective tissue cells of the gut and gills, and hepatocytes of one species of ray. The presence of antigen D10 in different tissues and species was confirmed by both an indirect ELISA and immunoblot analysis of tissue extracts. Our observations suggest that the D10 epitope characterises a subpopulation of mucus-secreting cells, predominantly of the foregut and associated organs, which has been conserved throughout terrestrial vertebrate evolution.

Notizen: Abstract  This paper outlines novel techniques for producing qualitative visualisations of density fluctuations and for obtaining quantitative whole-field density measurements in two-dimensional density-stratified flows. These techniques, which utilise image processing technology, are much simpler to set up than the classical schlieren and interferometry methods, and provide useful information in situations where shadowgraph is of little or no value. Moreover, they may be set-up to analyse much larger domains than is feasible with the classical approaches, and do not require high quality optical windows in the experimental apparatus. Ultimately the greatest strength of these techniques is the ability to extract accurate, quantitative measurements of the density field. Application of these techniques is illustrated by an internal wave field produced by an oscillating cylinder. Recent theoretical advances for this classical problem make it the ideal test bed. Results are presented for both a circular and a square cylinder oscillating vertically in a linear stratification. Further aspects of the techniques are illustrated by considering thermal convection from a hand and flow over an obstacle towed through a density stratified fluid.

Notizen: Abstract We report an upper-division undergraduate solid-state materials chemistry experiment involving the pit and crevice corrosion of a copper surface caused by an aqueous NaCl solution simulating a seawater environment. Surface corrosion of the copper can be shown quite dramatically using atomic force microscopy (AFM) within only hours of exposure to the saline solution. The copper surfaces can also be treated with an alkanethiol solution to form a self-assembled monolayer (SAM) on the surface. When exposed to the salt-water solution, the SAM layer is shown by AFM to protect the surface from corrosion. We have also shown that several different AFM analysis methods are needed to adequately quantify the surface features including roughness and power spectral density. This experiment enables students to not only see how AFM can be used to observe changes in surface morphology, but also learn to develop an understanding of the analysis techniques used to quantify AFM data.