Contrasting cytosolic glutathione redox dynamics under abiotic and biotic stress in barley as revealed by the biosensor Grx1-roGFP2

Barley is a staple crop of major global importance and relatively resilient to a wide range of stress factors in the field. Transgenic reporter lines to investigate physiological parameters during stress treatments remain scarce. We generated and characterized transgenic homozygous barley lines (cv. Golden Promise Fast) expressing the genetically encoded biosensor Grx1-roGFP2, which indicates the redox potential of the major antioxidant glutathione in the cytosol. Our results demonstrated functionality of the sensor in living barley plants. We determined the glutathione redox potential (EGSH) of the cytosol to be in the range of -308 mV to -320 mV. EGSH was robust against a combined NaCl (150 mM) and water deficit treatment (-0.8 MPa) but responded with oxidation to infiltration with the phytotoxic secretome of the necrotrophic fungus Botrytis cinerea. The generated reporter lines are a novel resource to study biotic and abiotic stress resilience in barley, pinpointing that even severe abiotic stress leading to a growth delay does not automatically induce cytosolic EGSH oxidation, while necrotrophic pathogens can undermine this robustness.

Genome-wide analyses of light-regulated genes in Aspergillus nidulans reveal a complex interplay between different photoreceptors and novel photoreceptor functions

Fungi sense light of different wavelengths using blue-, green-, and red-light photoreceptors. Blue light sensing requires the “white-collar” proteins with flavin as chromophore, and red light is sensed through phytochrome. Here we analyzed genome-wide gene expression changes caused by short-term, low-light intensity illumination with blue-, red- or far-red light in Aspergillus nidulans and found that more than 1100 genes were differentially regulated. The largest number of up- and downregulated genes depended on the phytochrome FphA and the attached HOG pathway. FphA and the white-collar orthologue LreA fulfill activating but also repressing functions under all light conditions and both appear to have roles in the dark. Additionally, we found about 100 genes, which are red-light induced in the absence of phytochrome, suggesting alternative red-light sensing systems. We also found blue-light induced genes in the absence of the blue-light receptor LreA. We present evidence that cryptochrome may be part of this regulatory cue, but that phytochrome is essential for the response. In addition to in vivo data showing that FphA is involved in blue-light sensing, we performed spectroscopy of purified phytochrome and show that it responds indeed to blue light.

Fungi are microorganisms with important roles in the environment, as symbionts, as pathogens, or as workhorses in biotechnology. They constantly need to adapt to changing environmental conditions, often far away from their optima. One important environmental factor, fungi respond to is ambient light. The presence of light tells them if they are exposed to a surface and thus potentially to heat, harmful irradiation, or desiccation or other stressful conditions, or whether they are growing inside soil or litter with more constant conditions. Interestingly, many fungi harbor photosensors for blue-, green- and red light. We show here that in the model fungus Aspergillus nidulans a large proportion of the genome is under light control, and many genes are regulated through phytochrome and thus by red light. However, phytochrome is also used for blue-light sensing. Many genes are controlled by blue- and by red light signaling systems, but many also respond only to specific wavelengths. The study provides important groundwork for future research to unravel how different genes are regulated at the molecular level and to decipher the biological meaning for the complex light-regulatory systems found in fungi.

Glucocorticoid-remediable aldosteronism is associated with severe hypertension in early childhood

OBJECTIVES

To review the childhood course of glucocorticoid-remediable aldosteronism (GRA) in order to provide management guidelines for hypertension in children.

METHODS

Records for 20 children with GRA (aged 1 month to 18 years; 16 with hypertension) were retrospectively reviewed.

RESULTS

Of the 16 children with GRA who developed hypertension, 50% had moderate-severe hypertension (blood pressure [BP] >99th centile for age and sex); 32% had mild hypertension (BP >95th and <99th centile), and 18% had borderline normal BP (BP >90th and <95th centile). Eight of 16 children with hypertension who received directed monotherapy (glucocorticoid suppression or aldosterone receptor/sodium epithelial channel antagonists) maintained BP below the 90th centile. Three additional subjects receiving a combination of directed therapies or a combination of directed therapies and nifedipine were unable to achieve BP control. At GRA diagnosis, 5 of 8 children were normokalemic, and plasma renin activity was suppressed in 5 of 5 subjects.

CONCLUSIONS

Clinicians should have a high index of suspicion for GRA, especially in children with severe hypertension and a positive family history of early-onset hypertension and/or premature hemorrhagic stroke. Directed monotherapy is often successful in controlling BP in GRA.

Evaluation and management of proteinuria and nephrotic syndrome in children: recommendations from a pediatric nephrology panel established at the National Kidney Foundation conference on proteinuria, albuminuria, risk, assessment, detection, and elimination (PARADE)

OBJECTIVE

The development of this review article evolved from a National Kidney Foundation consensus conference on recent advances in the importance of evaluating and treating proteinuria. From this conference, a series of recommendations for the evaluation of adults with proteinuria was published. Because specific pediatric aspects of the problem were outside the scope of the original National Kidney Foundation publication, an ad hoc committee of 6 pediatric nephrologists who were active participants in the National Kidney Foundation conference was established to provide primary care physicians with a concise, up-to-date reference on this subject.

METHODS

The recommendations that are given represent the consensus opinions of the authors. These are based on data from controlled studies in children when available, but many of the opinions are, by necessity, based on uncontrolled series in children or controlled trials performed in adults, because controlled trials in children have not been performed to evaluate many of the treatments described.

RESULTS AND CONCLUSIONS

These recommendations are intended to provide primary care physicians with a useful reference when they are faced with a young child or teenager who presents with proteinuria, whether this is mild and asymptomatic or more severe, leading to nephrotic syndrome.

Assessment of structure and function in progressive renal disease

The incidence and prevalence rates of end-stage renal disease (ESRD) in the United States continue to increase. In 1995, the incidence rate was 262 per million population, with a point prevalence rate of 975 per million population. The exact number of individuals with abnormal renal function but not yet at end stage is difficult to assess. Crude estimates suggest that approximately 0.4% of the U.S. population has serum creatinine values greater than 2.0 mg/dl. In some sub-populations, such as African Americans, the estimate is + as high as 1.0%. The rate of progression, likewise, is difficult to assess. In general, renal manifestations of certain systemic diseases such as diabetes mellitus and systemic lupus erythematosus, and those with significant proteinuria (usually greater that 3.0 g/24 hr) seem to have a more rapid progressive course to end stage. If intervention is expected to be successful in halting or slowing down progression, accurate assessment of the early manifestations of renal disease, structure, and function need to be established. Currently accepted methods of assessment of renal disease include measurement of renal function such as serum creatinine and glomerular filtration rate, measurement of proteinuria, assessment of tubular function, glomerular sieving and permselectivity, radiologic imaging techniques, and evaluation of histo-morphometry. Interventions that have been shown to slow progression include control of hypertension, and treatment modalities that reduce proteinuria, such as, the use of angiotensin converting enzyme inhibitors. Further clinical and basic science studies are needed to accurately define the important predictors of progression, and interventions that are effective in slowing or halting progression.

Intravenous cysteamine therapy for nephropathic cystinosis

A 4-y-old boy with nephropathic cystinosis and gastrointestinal dysmotility of unknown etiology was treated with i.v. cysteamine over a period of 10 mo. Thirty minutes after a dose of 10 mg/kg cysteamine free base, the leukocyte cystine value had fallen from 11.9 to 4.9 nmol of half-cystine/mg of protein. When cysteamine was given every 6 h, the leukocyte cystine concentration, measured 5-7 h after a dose, decreased with increasing cysteamine doses up to 17 mg/kg; at this dose the cystine value was 1.1 nmol of half-cystine/mg of protein, or 9% of the untreated value. Oral administration of approximately 16 mg/kg per dose every 6 h to this patient over the previous 3 y achieved similar leukocyte cystine depletion, to 1.2 nmol of half-cystine/mg of protein. The plasma cysteamine concentration 30 min after a dose of 10 mg/kg was 71 microM; 5-7 h after a dose of up to 20 mg/kg, the concentration was below 5 microM. Dimethylsulfide was elevated in the breath and urine of this boy after, but not before, the initiation of i.v. cysteamine therapy. Ten months after the start of therapy, the patient tolerated 250 mg (14 mg/kg) every 8 h. Adverse effects of this treatment included lethargy and increased nausea and vomiting when a schedule of therapy every 6 h was attempted. This investigation demonstrates that cysteamine given through a central venous catheter is effective in reducing leukocyte cystine levels.

Pathophysiology of vascular smooth muscle in renin promoter-T-antigen transgenic mice

The pathophysiological consequence of targeted production of SV-40 T-antigen to renin-expressing cells in the kidney of transgenic mice is reported. A histopathologic analysis of the kidney from adult transgenic mice (12-16 wk old) revealed the presence of severe vascular lesions manifested by marked atypical hyperplasia of vascular smooth muscle. The levels of plasma renin, kidney renin, and kidney renin mRNA were examined in 6- and 9-wk-old transgenic mice and were found to be significantly lower than their age-matched non-transgenic littermates and were nonresponsive to captopril treatment. However, there was no significant difference in conscious mean arterial pressure between transgenic and non-transgenic mice. The levels of renal renin mRNA in transgenics and nontransgenic littermates were compared throughout ontogeny and were found to be equal in newborns, elevated 3- to 5-fold in 1-wk-old transgenics, and yet decreased 10-fold by 6 wk of age in transgenic mice. Expression of the transgene in the kidney exhibited the proper developmental pattern and was properly restricted to juxtaglomerular cells in neonatal mice. Nevertheless, in adult mice, T-antigen-containing cells were found throughout the entire renal arterial tree. The observed ability of renal vascular cells to be recruited to express both renin and T-antigen suggests a mechanism that can explain the development of the renal pathology in these mice.

Isolation and characterization of renin-expressing cell lines from transgenic mice containing a renin-promoter viral oncogene fusion construct

We constructed transgenic mice containing a renin-promoter SV40 T antigen fusion transgene with the intention of inducing neoplasia in renin-expressing cells and isolating renin-expressing cell lines in vitro. We examined six kidney tumors from mice representing three different transgenic lines and found they expressed their endogenous renin gene. Initially, five nonclonal kidney tumor-derived cell lines were established which expressed their endogenous renin gene in addition to the transgene. They retained active renin intracellularly and constitutively secreted an inactive form of renin (prorenin). One of these cell lines was cloned to homogeneity. This line maintained high level expression of renin mRNA throughout 3 months of continuous culture. Although the cells contained an equal proportion of active and inactive renin, the species constitutively secreted into the media was predominantly (95%) prorenin. However, active renin secretion was stimulated 2.3- and 4.6-fold by treatment with 8-bromo-cAMP after 4 and 15 h, respectively. In addition, the presence of multiple secretory granules was confirmed by ultrastructural analysis. These cells, which express renin mRNA and can regulate secretion of active renin, should provide an excellent tool for studying renin gene regulation and secretion. Furthermore, these mice should provide a useful source for the establishment of renin-expressing cell lines from a variety of renin-expressing tissues.

A comparative study of the distributions of renin and angiotensinogen messenger ribonucleic acids in rat and mouse tissues

Previous studies have reported the presence of renin mRNAs in several mouse tissues and angiotensinogen mRNAs in various rat tissues. Clarification as to whether renin and angiotensinogen mRNAs are coexpressed in the same tissues of the same animal species is important for understanding the biology of the tissue renin-angiotensin system. We employed mouse renin cDNA and rat angiotensinogen cDNA to compare tissue distributions of renin and angiotensinogen in RNAs of the rat and mouse. Both cDNA probes readily cross-hybridize with the corresponding mRNA of the other species. Our results demonstrate several patterns of distribution. Renin and angiotensinogen mRNAs are readily detected in kidney and adrenals of both species. In brain and heart, angiotensinogen mRNAs are present in concentrations that far exceed renin mRNA levels in these organs in both species. In mouse and rat livers, angiotensinogen, but not renin, mRNA is demonstrated. In rat testis, only renin mRNA can be detected, whereas in mouse testes both renin and angiotensinogen mRNA are present. In CD-1 male mouse submandibular gland, renin mRNA exists in high concentrations, whereas angiotensinogen mRNA is present in low levels. In contrast, neither renin nor angiotensinogen mRNA could be detected in rat salivary gland. In summary, our study demonstrates the widespread codistribution of renin and angiotensinogen mRNAs in many tissues of both species, allowing for the possibility of local angiotensin production. However, tissue and species differences in these gene expressions also exist. Understanding differential tissue expressions of these genes will provide additional important insight into the biology of the renin-angiotensin system.

Identification of renin and angiotensinogen messenger RNA sequences in mouse and rat brains

Components of the renin angiotensin system have been demonstrated in mouse and rat brains. However, local synthesis of renin has not been documented. In this study, we employed mouse submandibular gland renin complementary DNA (pDD-1D2) and rat liver angiotensinogen complementary DNA (pRang3) to examine whether renin and angiotensinogen RNA sequences exist in mouse and rat brain. Angiotensinogen messenger RNA sequences were readily demonstrable in whole rat and mouse brain using Northern blot hybridization analysis. Using large quantities (greater than 100 micrograms) of brain total RNA and the sensitive complementary RNA probe, we were able to detect low levels of renin RNA sequences in the brains of both species. The relatively low concentration of brain renin messenger RNA and high concentration of angiotensinogen messenger RNA raises several interesting questions about the distribution of these two proteins and their relative contribution to activity of the brain renin-angiotensin system. In summary, our data demonstrate the expression of both renin and angiotensinogen genes in mouse and rat brains and provide definitive evidence for an independent endogenous brain renin angiotensin system.

Hypertension in children. Increased efficacy of technetium Tc 99m succimer in screening for renal disease

Renal scintigraphy with technetium Tc 99m succimer (DMSA) and technetium Tc 99m pentetate (DTPA) was used to study 80 hypertensive pediatric and adolescent patients. Renal abnormalities such as asymmetry of function, size, or shape were identified in 13 patients. Both excretory urography and technetium Tc 99m pentetate studies were successful in detecting 54% of the abnormalities in patients studied; technetium Tc 99m succimer identified 92%. The accuracy of the latter was 96%, with a specificity of 97%. The ability of technetium Tc 99m succimer renal scintigraphy to identify accurately the presence or absence of renal abnormalities warrants its inclusion in the initial examination of pediatric and adolescent patients with hypertension.

Hyperlipidemia after renal transplantation in children

A cross-sectional survey of 32 children who received renal allografts was undertaken to evaluate lipid profiles in a pediatric transplant population. Ages ranged from 8 to 18 years, and serum creatinine concentrations varied from 0.5 to 5.6 mg/100 ml (mean, 1.4 mg/100 ml). Fifty percent of patients showed an abnormal lipoprotein electrophoresis, and these were evenly divided between type II and type IV patterns. The data suggest that patients with type II pattern tend to be receiving higher doses of prednisone, and increasing levels of cholesterol and triglyceride are also associated with higher corticosteroid dosages. In contrast to the observations of others in dialysis patients, measurements of glucose metabolism such as fasting blood sugar and fasting insulin levels were not associated with lipid abnormalities in this population. Lipid abnormalities following renal transplantation in children are similar to those described in adults, and may contribute to morbidity in the years following successful renal transplantation.