Regional Specificity in Alterations of Rat Brain Copper and Catecholamines Following Perinatal Copper Deficiency

Abstract: Perinatal copper deficiency was studied in 1-month-old female and male Sprague-Dawley rat offspring to investigate regional changes in brain copper and catecholamine levels. Offspring of dams given the low copper treatment beginning at day 7 of gestation exhibited signs characteristic of deficiency such as impaired growth and 10-fold lower liver copper levels compared with copper-adequate controls. Regional analysis of brain copper by graphite furnace atomic absorption spectroscopy revealed uniform and severe reduction of copper to levels 20 ± 3% of controls in all regions, except the hypothalamus, where reductions to 56 and 28% of those in copper-adequate females and males, respectively, were measured. HPLC analysis revealed significant reductions in norepinephrine levels in cerebrum, midbrain, corpus striatum, cerebellum, and medulla-pons of copper-deficient offspring ranging between 39 and 67% of control values. There were no significant differences in norepinephrine concentration in the hypothalamus. There was a significant, one-third reduction of dopamine in the corpus striatum of copper-deficient male rats. Consistent with altered in vivo dopamine β-monooxygenase activity, there were five-, three-, and twofold elevations of dopamine in cerebellum, medulla-pons, and hypothalamus of copper-deficient rats. Spectrophotometric measurement of in vitro dopamine β-monooxygenase activity of brain and adrenal homogenates was higher in copper-deficient rats, confirming prior work. An explanation for the in vitro data is unclear. Changes in copper and catecholamine levels were influenced by diet and were regionally selective, especially in the hypothalamus.     

Fast Cytoplasmic pH Regulation in Acid-Stressed Leaves

Induction of photosynthesis in leaves was prolonged, and steadystate photosynthesis was inhibited by very high CO₂ concentrationswhich cause cytoplasmic acidification. Prolonged exposure tohigh CO₂ relieved initially observed inhibition of photosynthesisat least partially. The sensitivity of carbon assimilation tohigh CO₂ was different in different plant species. Acidificationby CO₂ (or subsequent alkalization) was detected by measuringrapid CO₂-release from the tissue and by monitoring fluorescenceof pH-indicating dyes which had been fed to the leaves throughthe petiole. The results indicate that two different mechanismsoperate in leaves to achieve and maintain pH homeostasis. Rapidand efficient pH-adjustment is provided by proton/cation exchangeacross the tonoplast. Slower and less efficient regulation occursby formation or consumption of base. In the presence of highCO₂ concentrations, protons are pumped from the cytosol intoalready acidic vacuoles. In turn, vacuolar cations replace exportedprotons in the cytosol permitting bicarbonate accumulation andincreasing the pH of the acidified cytosol. Similarly effectiveand fast proton/cation exchange relieves acid-stress in thechloroplast stroma and permits photosynthesis to proceed withhigh quantum efficiency or high light-saturated rates in thepresence of CO₂ concentrations which would, in the absence offast cytoplasmic pH regulation, inhibit photosynthesis. By inference,proton/cation exchange must also occur across the mitochondrialboundary. After cytoplasmic pH adjustment in the presence ofhigh CO₂, removal of CO₂ results in transient cytoplasmic alkalizationand, subsequently, in the return of cytoplasmic pH values tolevels observed prior to acid-stress. In addition to fast pHregulation by rapid proton/cation exchange across biomembranes,slow base production (e.g. NH₃-formation) also contributes torelieving acid stress. Base produced in the presence of highCO₂ is rapidly consumed after removal of CO₂. Implications of the findings in regard to forest damage by potentiallyacidic air pollutants such as SO₂ are briefly discussed. (Received November 8, 1993; Accepted February 3, 1994)     

Comparison of prevalence of schizophrenia among residents of hostels for homeless people in 1966 and 1992.

OBJECTIVE--To determine whether the prevalence of schizophrenia among the homeless population of Edinburgh resident in hostels has changed between 1966 and 1992. DESIGN--Comparison of two cross sectional surveys. SETTINGS--Hostels for homeless people in Edinburgh. SUBJECTS--In 1966 a random sample of 98 residents of three common lodging houses. In 1992 a random sample of 198 residents of nine hostels. MAIN OUTCOME MEASURE--Prevalence of schizophrenia. RESULTS--The prevalence of schizophrenia in 1992 was 12/136 (9%) compared with 20/79 (25%) in 1966 (odds ratio 0.29; 95% confidence interval 0.13 to 0.62; P = 0.001). Adjustment for confounding by age, current hostel, and duration of unemployment by means of logistic regression produced an adjusted odds ratio of 0.22 (0.08 to 0.58). CONCLUSIONS--The prevalence of schizophrenia was lower in 1992 even after other changes in the population resident in hostels occurring between 1966 and 1992 were taken into account. The findings are not consistent with an increase in the prevalence of schizophrenia among homeless people despite a 66% reduction in adult psychiatric beds in the region during 1966-92.     

Taxonomy ofHordeum caespitosum,H. jubatum,andH. lechleri (Poaceae: Triticeae)

Hordeum caespitosum Scribner,H. jubatum L., andH. lechleri (Steudel)Schenck are very similar in appearance and therefore until recently were mostly not recognized as separate entities. The first two are tetraploid and natives to North America, but the second occurs naturally in eastern Siberia and has been introduced in Europe and South America and may become a cosmopolitan weed. The third is hexaploid and South American. This study analyses their morphological diversity by means of selected multivariate techniques in order to determine if there is justification to recognize them as three separate morphological species. Logistic discrimination, although based on a reduced set of characters, yielded the highest percent of correct assignments. A linear discriminant function is provided and validated by 100 bootstrap repeats. Canonical discriminant analysis indicated three groups. It is subsequently concluded that the three are separate morphological species. Although a linear discriminant function is given, a traditional identification key is provided based on the palea length and triad (the group of three spikelets at each rachis node) length.     

Characterization of recurrent somatic embryogenesis of alfalfa on auxin-free medium

Callus cultures from 300 genotypes of alfalfa (Medicago sativa L.) were initiated from leaf, petiole, and internode explants placed on Blaydes medium containing 10.74 M -naphthaleneacetic acid, 11.42 M indole-3-acetic acid, and 9.29 M kinetin. Five genotypes produced somatic embryos. Upon transfer of these embryos to growth regulator-free Murashige and Skoog medium with B₅ vitamins, new somatic embryos repeatedly formed directly on older somatic embryos without an intervening callus phase in a cycle lasting about 30 days. These cultures have been maintained for two years, during which time their embryogenic capacity has remained stable. New embryogenic cultures could be started repeatedly from these genotypes. The elimination of sugars from the medium could stop recurrent embryogenesis. Glucose, maltose, and fructose stimulated recurrent embryogenesis more effectively than sucrose. Sucrose was superior to lactose, while sorbitol and mannitol did not stimulate recurrent somatic embryogenesis. The absence of nicotinic acid in the medium, as long as sucrose was present, was lethal to embryos of three of the five tested genotypes. The ability of this system to propagate embryos exponentially offers potential for development of new gene transfer systems and application to artificial seed technology.Abbreviations NAA -naphthaleneacetic acid - RSE recurrent somatic embryogenesis     

The gene fimU affects expression of Salmonella typhimurium type 1 fimbriae and is related to the Escherichia coli tRNA gene argU

The gene fimU, located on a recombinant plasmid carrying the Salmonella typhimurium type 1 fimbrial gene cluster is closely related to the Escherichia coli tRNA gene argU. The fimU gene complements an E. coli argU mutant that is a P2 lysogen, thereby allowing the phage P4 to grow in this strain but preventing the growth of phage lambda. In addition, fimU was shown to be involved in fimbrial expression since transformants of the E. coli argU mutant could produce fimbriae only in the presence of fimU but not in its absence, whereas in an E. coli argU ⁺ strain fimbriation did not require the fimU gene.     

Recovery and evaluation of soybean plants transgenic for aBacillus thuringiensis var.Kurstaki insecticidal gene

Summary Lepidopteran insects are major defoliating pests of soybean in the southeastern United States. Soybean plants transgenic for a nativecryIA(b) gene fromBacillus thuringiensis var.kurstaki HD-1 were obtained. Embryogenic cultures were induced by plating cotyledons on a Murashige and Skoog-based medium supplemented with 40 mg/liter of 2,4-dichlorophenoxyacetic acid (2,4-D). The embryogenic cultures were maintained in liquid medium containing 5 mg/liter 2,4-D. These cultures were subjected to microprojectile bombardment, followed by selection on 50 mg/liter hygromycin. Resistant embryogenic cell lines were transferred to growth regulator-free medium to permit recovery of mature somatic embryos. After a desiccation period, the somatic embryos were returned to growth regulator-free medium for conversion into plants. Southern hybridization analysis verified transformation. Feeding assays of T₁ plants from one cell line deterred feeding, development, and survival of velvetbean caterpillar at a level comparable to that of GatIR81-296, a soybean breeding line with a high level of insect resistance. Reduced feeding on T₁ plants correlated with the presence of the transgene.     

Pan-Arctic soil moisture control on tundra carbon sequestration and plant productivity

Long-term atmospheric CO₂ concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength. In this study, we used a record of nearly 100 site-years of eddy covariance data from 11 continuous permafrost tundra sites distributed across the circumpolar Arctic to test the temperature (expressed as growing degree days, GDD) responses of gross primary production (GPP), net ecosystem exchange (NEE), and ecosystem respiration (ER) at different periods of the summer (early, peak, and late summer) including dominant tundra vegetation classes (graminoids and mosses, and shrubs). We further tested GPP, NEE, and ER relationships with soil moisture and vapor pressure deficit to identify potential moisture limitations on plant productivity and net carbon exchange. Our results show a decrease in GPP with rising GDD during the peak summer (July) for both vegetation classes, and a significant relationship between the peak summer GPP and soil moisture after statistically controlling for GDD in a partial correlation analysis. These results suggest that tundra ecosystems might not benefit from increased temperature as much as suggested by several terrestrial biosphere models, if decreased soil moisture limits the peak summer plant productivity, reducing the ability of these ecosystems to sequester carbon during the summer.     

Subgrouping of bacterial populations by cellular fatty acid composition

Abstract The cellular fatty acid composition of six bacterial species isolated from the seeds and leaves of sugar beet ( Beta vulgaris ) and from soil were analysed. The quantitative data from the fatty acid methyl ester (FAME) profiles were highly reproducible. Numerical analysis of Xanthomonas maltophilia . FAME profiles sub-grouped strains according to when they were isolated in the growing season. The analytical method used was sensitive enough to differentiate strains of Klebsiella terrigena isolated from either soil or leaves. The results from this study confirm reports that analyses of bacterial FAME composition were rapid to perform, specific and allowed differentiation of strains within the same species.     

Vertically stratified frugivore community composition and interaction frequency in a liana fruiting across forest strata

Vertical stratification is a key feature of tropical forests and structures plant–frugivore interactions. However, it is unclear whether vertical differences in plant-frugivore interactions are due to differences among strata in plant community composition or inherent preferences of frugivores for specific strata. To test this, we observed fruit removal of a diverse frugivore community on the liana Marcgravia longifolia in a Peruvian rain forest. Unlike most other plants, Marcgravia longifolia produces fruits across forest strata. This enabled us to study effects of vertical stratification on fruit removal without confounding effects of plant species and stratum. We found a high number of visits of a few frugivore species in the understorey and a low number of visits of many different frugivores in the canopy and midstorey. Whereas partial and opportunistic frugivores foraged across strata with differing frequencies, obligate frugivores were only found eating fruits in the higher strata. Avian frugivores foraging in the canopy were mainly large species with pointed wings, whereas under- and midstorey avian foragers were smaller with rounded wings. Our findings suggest a continuous shift in the frugivore community composition along the vertical gradient, from a few generalized frugivores in the understorey to a diverse set of specialized frugivores in the canopy. This shift in the frugivore community leads to correlated, reciprocal changes from specialized to generalized plant-frugivore interactions. Thus, we conclude that vertical niche differentiation between species in tropical forests persists even when food resources are available across strata. This highlights its role for promoting biodiversity and ecosystem functioning.