Quantifying the effects of forestry practices on the recovery of upland streams and lochs from acidification.

Trends in long-term chemistry data are presented for 37 acidified upland streams and lochs, located in four areas (A, B, C and D) across Scotland, to provide a comparison between recovery rates of moorland catchments and forest catchments at different stages of the management cycle. For all sites, non-marine sulfate (nm-SO(4)) showed a significant decline in annual median concentrations, the greatest decline being in streams draining felled catchments, which showed a 50% greater decline than catchments with moorland or young, aggrading forests. A similar pattern was found for chloride (Cl) concentrations in Area C, which reflected the reduced interception of sea-salt aerosols following clearfelling. However, high elevation moorland sites in Area D also revealed significant declines in Cl while trends in aggrading forest sites in this area were insignificant. Alkalinity (ALK) and pH increased more at sites where felling had taken place than at moorland or young forest sites while aggrading forest catchments appeared to be most resistant to changes in pH and ALK. Associated with these acid-base changes was a corresponding decline in labile aluminium (Al-L) concentrations. The pattern of nitrate (NO(3)) change was especially affected by the timing of felling in forested catchments. Large negative trends in NO(3) at stream sites were associated with felling during the early part of the study period. This downward trend was further enhanced as NO(3) concentrations fell below pre-felling levels as the second rotation crop became established. Few forest sites showed significant increases in NO(3) due to felling in the latter part of the study period. Most moorland loch sites showed a small but significant increase in NO(3,) probably in response to similar increases in N deposition and/or climatic impacts. Dissolved organic carbon (DOC) increased significantly at both forest and moorland sites, however, the extent of these increasing trends appeared to be positively correlated with absolute DOC concentrations. Despite the complex response of streams and lochs during the various stages of the forest cycle, especially for NO(3), both forest and moorland catchments showed generally similar and rapid responses to reductions in S deposition. Nevertheless, forested sites are still more acid and have higher concentrations of toxic forms of Al than moorland sites. Although the proposed emission reductions in Europe are likely to result in a continuing decline in S and N loadings to catchments, the continuing policy of planting second rotation forests in these acidified catchments may, in the long-term, delay or halt chemical and biological recovery. However, in the short-term, any increase in the uptake of N deposition by aggrading forests should help to counteract the acidifying effects of a small increase in the interception of S and N compounds.

Long-term trends in pH, aluminium and dissolved organic carbon in Scottish fresh waters; implications for brown trout (Salmo trutta) survival.

Over the past 30 years upland streams and lochs in Scotland have shown significant signs of recovery from acidification, particularly in terms of declining concentrations of non-marine sulphate (nm-SO(4)). Long-term index sites in central and southwest Scotland reveal a significant decline in the concentration of biologically important components, notably acidity (H(+)) and labile (toxic) forms of aluminium (Al-L), whilst dissolved organic carbon (DOC) and complexed forms of aluminium (AL-NL) have increased significantly. Although these improvements should increase the probability of brown trout survival, and have resulted in increased acid neutralising capacity (ANC) in fishless streams to values close to current critical limits, there is still a relatively poor correlation between ANC and current fish status. Site to site variability appears to be linked to the relative contribution of (H(+)), Al-L and DOC within the critical ANC (ANC(CRIT)) range. It is proposed that ANC(CRIT) should cover a range of ANC values as a function of Al-L concentration. Based on field studies an empirical range of critical ANC values are suggested which better predict the presence of a sustainable brown trout population.

Long-term variability in the deposition of marine ions at west coast sites in the UK Acid Waters Monitoring Network: impacts on surface water chemistry and significance for trend determination.

Eight lake sites in central and south-west Scotland, north-west England and north Wales, forming part of the UK Acid Waters Monitoring Network (UKAWMN), have been studied with regard to the influence of marine ions on surface water chemistry. Since monitoring began in 1988 these sites have exhibited large and long-term variation in Cl concentration, which are consistent between regions and can be linked to inter-annual variations in wet deposition. Through regression analysis against Cl, the response of other solutes to these fluctuations has been assessed. Sites show a highly consistent pattern of Na, and Mg retention during periods of high Cl, in accordance with the 'sea-salt' mechanism of marine cation adsorption onto soil exchange sites following large marine inputs. An associated displacement of cations with non-marine sources is also observed, with one or more of non-marine Ca, labile Al and hydrogen ions exhibiting a positive relationship with Cl at all sites. The relative extent to which these are released appears not to follow a simple relationship to site acidity, and may be linked to site/region-specific geology and soil characteristics. In addition, an inverse relationship between non-marine SO4 and Cl is observed at five of the sites, and the possibility is considered that a sea-salt related process, with soil retention and subsequent release, may also operate for SO4. A mechanism that might explain this process is suggested. The impact of marine inputs on non-marine solutes, including important indicators of acidification such as pH, labile Al and non-marine SO4, has clear implications for the detection of long-term trends in acidity status and is, therefore, of particular relevance to the UKAWMN. Due to their unpredictability, and the long timescale over which they operate, fluctuations caused by marine inputs may be difficult to separate from acid deposition related long-term trends. Evidence from a longer Cl time series from mid-Wales shows that fluctuations in concentration could be linked to the North Atlantic Oscillation and might therefore be expected to exhibit a similar, decal periodicity. Currently, the UKAWMN dataset only appears long enough to represent one climatic cycle. Consequently, and since few surface water chemistry datasets in the UK extend over more than a decade, it is important that: (a) trend analyses of current data from marine-impacted areas take account of possible marine input cycles; and (b) long-term monitoring is maintained into the future so that the impact of these cycles can be better quantified, and distinguished from anthopogenically-induced long-term changes.

Talk to your staff about distance education.

Most health care professionals and managers feel the need to finish their undergraduate or graduate degree to maintain their present position or to advance to a higher one. Distance education is a convenient alternative where students complete their studies from home using the postal service or computer.

Recruiting and retaining staff in the twenty-first century.

There is a shortage of health care professionals across the country, as well as a shortage of registered nurses that is compromising patient care. This shortage will reach crisis proportions in the twenty-first century. Hospitals will have to upgrade their recruitment efforts and retain the employees that they have.

Distance education in the twenty-first century.

Most health care professionals and managers feel the need to finish their undergraduate or graduate degree to maintain their present position or to advance to a higher position. Distance education is a convenient alternative where students complete their studies from home using the postal service or computer.

Physical association of starch biosynthetic enzymes with starch granules of maize endosperm. Granule-associated forms of starch synthase I and starch branching enzyme II.

Antibodies were used to probe the degree of association of starch biosynthetic enzymes with starch granules isolated from maize (Zea mays) endosperm. Graded washings of the starch granule, followed by release of polypeptides by gelatinization in 2% sodium dodecyl sulfate, enables distinction between strongly and loosely adherent proteins. Mild aqueous washing of granules resulted in near-complete solubilization of ADP-glucose pyrophosphorylase, indicating that little, if any, ADP-glucose pyrophosphorylase is granule associated. In contrast, all of the waxy protein plus significant levels of starch synthase I and starch branching enzyme II (BEII) remained granule associated. Stringent washings using protease and detergent demonstrated that the waxy protein, more than 85% total endosperm starch synthase I protein, and more than 45% of BEII protein were strongly associated with starch granules. Rates of polypeptide accumulation within starch granules remained constant during endosperm development. Soluble and granule-derived forms of BEII yielded identical peptide maps and overlapping tryptic fragments closely aligned with deduced amino acid sequences from BEII cDNA clones. These observations provide direct evidence that BEII exits as both soluble and granule-associated entities. We conclude that each of the known starch biosynthetic enzymes in maize endosperm exhibits a differential propensity to associate with, or to become irreversibly entrapped within, the starch granule.

Inhibition and Ultraviolet-Induced Chemical Modification of UDP-Glucose:(1,3)-beta-Glucan (Callose) Synthase by Chlorpromazine : Mechanism of Chlorpromazine Binding to the Plant Plasma Membrane.

UDP-glucose:(1,3)-beta-glucan (callose) synthase (CS) from storage tissue of red beet (Beta vulgaris L.) was strongly inhibited by the phenothiazine drug chlorpromazine (CPZ). In the absence of ultraviolet irradiation, CPZ was a noncompetitive inhibitor with 50% inhibitory concentration values for plasma membrane and solubilized CS of 100 and 90 mum, respectively. Both the Ca(2+)- and Mg(2+)- stimulated components of CS activity were affected. CPZ inhibition was partially alleviated at saturating levels of Ca(2+), but not Mg(2+), suggesting that CPZ interferes with the Ca(2+)-binding site of CS. Binding experiments with [(14)C]CPZ, however, showed strong non-specific partitioning of CPZ into the plasma membrane, providing evidence that perturbation of the membrane environment is probably the predominant mode of inhibition. Ultraviolet irradiation at 254 nm markedly enhanced CPZ inhibition, with complete activity loss following exposure to 4 mum CPZ for 2 min. Inhibition followed a pseudo-first order mechanism with at least three CPZ binding sites per CS complex. Under these conditions, [(3)H]CPZ was covalently incorporated into plasma membrane preparations by a free radical mechanism; however, polypeptide labeling profiles showed labeling to be largely nonspecific, with many polypeptides labeled even at [(3)H]CPZ levels as low as 1 mum, and with boiled membranes. Although CPZ is one of the most potent known inhibitors of CS, its use as a photolabel will require a homogeneous CS complex or establishment of conditions that protect against the interaction of CPZ with specific binding sites located on various polypeptide components of the CS complex.

An Antisense Pectin Methylesterase Gene Alters Pectin Chemistry and Soluble Solids in Tomato Fruit.

Pectin methylesterase (PME, EC 3.1.11) demethoxylates pectins and is believed to be involved in degradation of pectic cell wall components by polygalacturonase in ripening tomato fruit. We have introduced antisense and sense chimeric PME genes into tomato to elucidate the role of PME in fruit development and ripening. Fruits from transgenic plants expressing high levels of antisense PME RNA showed <10% of wild-type PME enzyme activity and undetectable levels of PME protein and mRNA. Lower PME enzyme activity in fruits from transgenic plants was associated with an increased molecular weight and methylesterification of pectins and decreased levels of total and chelator soluble polyuronides in cell walls. The fruits of transgenic plants also contained higher levels of soluble solids than wild-type fruits. This trait was maintained in subsequent generations and segregated in normal Mendelian fashion with the antisense PME gene. These results indicate that reduction in PME enzyme activity in ripening tomato fruits had a marked influence on fruit pectin metabolism and increased the soluble solids content of fruits, but did not interfere with the ripening process.

Reversibility of lake acidification at the Round Loch of Glenhead, Galloway, Scotland.

Levels of acidic deposition have declined in Galloway over the last two decades. At the Round Loch of Glenhead this has led to a slight recovery from lake acidification, lake water pH rose by approximately 0.2 units between 1978 and 1989. The diatom flora of the lake has responded to this recovery and a clear floristic reversal dating to the late 1970s is apparent in the sediment cores studied. The detection of this reversibility trend, however, is dependent on the accumulation rate of individual cores. The trend could be detected only in cores with accumulation rates greater than 0.7 mm year(-1). It is also argued that sediment mixing has led to some loss of resolution of the sedimentary record.

Rapid Enrichment of CHAPS-Solubilized UDP-Glucose: (1,3)-beta-Glucan (Callose) Synthase from Beta vulgaris L. by Product Entrapment : Entrapment Mechanisms and Polypeptide Characterization.

Rapid enrichment of CHAPS-solubilized UDP-glucose:(1,3)-beta-glucan (callose) synthase from storage tissue of red beet (Beta vulgaris L.) is obtained when the preparation is incubated with an enzyme assay mixture, then centrifuged and the enzyme released from the callose pellet with a buffer containing EDTA and CHAPS (20-fold purification relative to microsomes). When centrifuged at high speed (80,000g), the enzyme can also be pelleted in the absence of substrate (UDP-Glc) or synthesis of callose, due to nonspecific aggregation of proteins caused by excess cations and insufficient detergent in the assay buffer. True time-dependent and substrate-dependent product-entrapment of callose synthase is obtained by low-speed centrifugation (7,000-11,000g) of enzyme incubated in reaction mixtures containing low levels of cations (0.5 millimolar Mg(2+), 1 millimolar Ca(2+)) and sufficient detergent (0.02% digitonin, 0.12% CHAPS), together with cellobiose, buffer, and UDP-Glc. Entrapment conditions, therefore, are a compromise between preventing nonspecific precipitation of proteins and permitting sufficient enzyme activity for callose synthesis. Further enrichment of the enzyme released from the callose pellet was not obtained by rate-zonal glycerol gradient centrifugation, although its sedimentation rate was greatly enhanced by inclusion of divalent cations in the gradient. Preparations were markedly cleaner when product-entrapment was conducted on enzyme solubilized from plasma membranes isolated by aqueous two-phase partitioning rather than by gradient centrifugation. Product-entrapped preparations consistently contained polypeptides or groups of closely-migrating polypeptides at molecular masses of 92, 83, 70, 57, 43, 35, 31/29, and 27 kilodaltons. This polypeptide profile is in accordance with the findings of other callose synthase enrichment studies using a variety of tissue sources, and is consistent with the existence of a multi-subunit enzyme complex.

Molecular cloning of tomato pectin methylesterase gene and its expression in rutgers, ripening inhibitor, nonripening, and never ripe tomato fruits.

We have purified pectin methylesterase (PME; EC 3.1.11) from mature green (MG) tomato (Lycopersicon esculentum Mill. cv Rutgers) pericarp to an apparent homogeneity, raised antibodies to the purified protein, and isolated a PME cDNA clone from a lambdagtll expression library constructed from MG pericarp poly(A)(+) RNA. Based on DNA sequencing, the PME cDNA clone isolated in the present study is different from that cloned earlier from cv Ailsa Craig (J Ray et al. [1989] Eur J Biochem 174:119-124). PME antibodies and the cDNA clone are used to determine changes in PME gene expression in developing fruits from normally ripening cv Rutgers and ripening-impaired mutants ripening inhibitor (rin), nonripening (nor), and never ripe (Nr). In Rutgers, PME mRNA is first detected in 15-day-old fruit, reaches a steady-state maximum between 30-day-old fruit and MG stage, and declines thereafter. PME activity is first detectable at day 10 and gradually increases until the turning stage. The increase in PME activity parallels an increase in PME protein; however, the levels of PME protein continue to increase beyond the turning stage while PME activity begins to decline. Patterns of PME gene expression in nor and Nr fruits are similar to the normally ripening cv Rutgers. However, the rin mutation has a considerable effect on PME gene expression in tomato fruits. PME RNA is not detectable in rin fruits older than 45 days and PME activity and protein begin showing a decline at the same time. Even though PME activity levels comparable to 25-day-old fruit were found in root tissue of normal plants, PME protein and mRNA are not detected in vegetative tissues using PME antibodies and cDNA as probes. Our data suggest that PME expression in tomato pericarp is highly regulated during fruit development and that mRNA synthesis and stability, protein stability, and delayed protein synthesis influence the level of PME activity in developing fruits.

Changes in Gene Expression during Tomato Fruit Ripening.

Total proteins from pericarp tissue of different chronological ages from normally ripening tomato (Lycopersicon esculentum Mill. cv Rutgers) fruits and from fruits of the isogenic ripening-impaired mutants rin, nor, and Nr were extracted and separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Analysis of the stained bands revealed increases in 5 polypeptides (94, 44, 34, 20, and 12 kilodaltons), decreases in 12 polypeptides (106, 98, 88, 76, 64, 52, 48, 45, 36, 28, 25, and 15 kilodaltons), and fluctuations in 5 polypeptides (85, 60, 26, 21, and 16 kilodaltons) as normal ripening proceeded. Several polypeptides present in ripening normal pericarp exhibited very low or undetectable levels in developing mutant pericarp. Total RNAs extracted from various stages of Rutgers pericarp and from 60 to 65 days old rin, nor, and Nr pericarp were fractionated into poly(A)(+) and poly(A)(-) RNAs. Peak levels of total RNA, poly(A)(+) RNA, and poly(A)(+) RNA as percent of total RNA occurred between the mature green to breaker stages of normal pericarp. In vitro translation of poly(A)(+) RNAs from normal pericarp in rabbit reticulocyte lysates revealed increases in mRNAs for 9 polypeptides (116, 89, 70, 42, 38, 33, 31, 29, and 26 kilodaltons), decreases in mRNAs for 2 polypeptides (41 and 35 kilodaltons), and fluctuations in mRNAs for 5 polypeptides (156, 53, 39, 30, and 14 kilodaltons) during normal ripening. Analysis of two-dimensional separation of in vitro translated polypeptides from poly(A)(+) RNAs isolated from different developmental stages revealed even more extensive changes in mRNA populations during ripening. In addition, a polygalacturonase precursor (54 kilodaltons) was immunoprecipitated from breaker, turning, red ripe, and 65 days old Nr in vitro translation products.

Fear of male homosexuality: cardiac responses of low and high homonegative males.

Males with high negative attitudes toward male homosexuality are often referred to in research as homophobics, yet it is unknown whether high homonegative males actually exhibit physiological responses characteristic of phobics. In a series of studies, heart rate was monitored in males with high or low negative attitudes toward male homosexuality as they viewed slides of landscapes and slides depicting explicit sexual activity. If high homonegativity is equivalent to homophobia, high homonegative males should exhibit heart rate acceleration to slides of male-male sexual activity, but, like low homonegative males, deceleration to all other slide types. Significant group effects were obtained only in the pilot study. Examination of individual response patterns in the pilot study and the two subsequent studies showed that high homonegative attitudes were necessary but not sufficient for heart rate acceleration to male-male slides. Results confirm the existence of the phobic type of heart rate acceleratory pattern among some, but not all, high homonegative males.

Rationale behind criterion-referenced clinical evaluation tools (a look at the ASRT recommendations).

Predicting and assessing learning outcomes through the use of behavioral objectives is increasing in programs of radiologic technology. The American Society of Radiologic Technologists has made available an instrument for evaluating student clinical performance and by examining the assumptions underlying this instrument we may better understand the theoretical basis upon which criterion-referenced evaluations are founded.