Restricted capacity for PSI-dependent cyclic electron flow in ΔpetE mutant compromises the ability for acclimation to iron stress in Synechococcus sp. PCC 7942 cells.

Exposure of wild type (WT) and plastocyanin coding petE gene deficient mutant (ΔpetE) of Synechococcus cells to low iron growth conditions was accompanied by similar iron-stress induced blue-shift of the main red Chl a absorption peak and a gradual decrease of the Phc/Chl ratio, although ΔpetE mutant was more sensitive when exposed to iron deficient conditions. Despite comparable iron stress induced phenotypic changes, the inactivation of petE gene expression was accompanied with a significant reduction of the growth rates compared to WT cells. To examine the photosynthetic electron fluxes in vivo, far-red light induced P700 redox state transients at 820nm of WT and ΔpetE mutant cells grown under iron sufficient and iron deficient conditions were compared. The extent of the absorbance change (ΔA(820)/A(820)) used for quantitative estimation of photooxidizable P700(+) indicated a 2-fold lower level of P700(+) in ΔpetE compared to WT cells under control conditions. This was accompanied by a 2-fold slower re-reduction rate of P700(+) in the ΔpetE indicating a lower capacity for cyclic electron flow around PSI in the cells lacking plastocyanin. Thermoluminescence (TL) measurements did not reveal significant differences in PSII photochemistry between control WT and ΔpetE cells. However, exposure to iron stress induced a 4.5 times lower level of P700(+), 2-fold faster re-reduction rate of P700(+) and a temperature shift of the TL peak corresponding to S(2)/S(3)Q(B)(-) charge recombination in WT cells. In contrast, the iron-stressed ΔpetE mutant exhibited only a 40% decrease of P700(+) and no significant temperature shift in S(2)/S(3)Q(B)(-) charge recombination. The role of mobile electron carriers in modulating the photosynthetic electron fluxes and physiological acclimation of cyanobacteria to low iron conditions is discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.

High Rates of Undiagnosed Target Organ Damage Among Adults with Elevated Blood Pressure or Diabetes Mellitus in a Community-Based Survey in Lesotho.

INTRODUCTION: Prevalence of elevated blood pressure (BP) and diabetes mellitus (DM) is increasing in sub-Saharan Africa. Data on target organ damage such as retinopathy, left ventricular hypertrophy (LVH), renal impairment and peripheral neuropathy (PN) among persons with elevated BP and/or DM in sub-Saharan Africa remain scarce. AIM: To determine at community-level the prevalence of retinopathy, LVH, renal impairment, and PN among adults with elevated BP and/or DM, and assess the association of elevated BP and/or DM with target organ damage in Lesotho. METHODS: During a household-based survey, a sub-sample of adults with elevated BP (≥ 140/90 mmHg) and/or DM (glycosylated hemoglobin ≥ 6.5%), as well as comparators (BP < 140/90 mmHg, HbA1c < 6.5%) were screened for retinopathy, LVH, renal impairment, and PN. We used multivariable logistic regression for inferential analysis. RESULTS: Out of 6108 participants screened during the survey, 420 with elevated BP only, 80 with DM only, 61 with elevated BP and DM, and 360 comparators were assessed for target organ damage. Among those with elevated BP, and among those with DM with or without elevated BP, prevalence of retinopathy was 34.6% (89/257) and 14.4% (15/104); renal impairment was 45.0% (156/347) and 42.4% (56/132), respectively. Among those with elevated BP, 2.3% (7/300) and 65.7% (224/341) had LVH and left ventricular concentric remodeling, respectively. PN, only assessed among those with DM, was present in 32.6% (42/129). Elevated BP was associated with increased odds of retinopathy (aOR, 19.13; 95% CI, 8.52-42.94; P < 0.001) and renal impairment (aOR, 1.80; 95% CI, 1.27-2.55; P = 0.001). Presence of both elevated BP and DM was associated with an increased odds of retinopathy (aOR, 16.30; 95%CI, 5.69-46.68; P < 0.001), renal impairment (aOR, 2.55; 95% CI, 1.35-4.81; P = 0.004), and PN (aOR, 2.13; 95% CI, 1.04-4.38; P = 0.040). CONCLUSION: We found a high prevalence of undiagnosed target organ damage among adults with elevated BP and/or DM during community-based screening. These findings emphasize the importance of regular prevention and screening activities in this setting.

Absence of the major light-harvesting antenna proteins alters the redox properties of photosystem II reaction centres in the chlorina F2 mutant of barley.

Although the chlorina F2 mutant of barley specifically exhibits reduced levels of the major light-harvesting polypeptides associated with photosystem II (PSII), thermoluminescence measurements of photosystem reaction centre photochemistry revealed that S2/S3QB- charge recombinations were shifted to lower temperatures, while the characteristic peak of S2QA- charge recombinations was shifted to higher temperatures compared with wild-type (WT) barley. Thus, we show that the absence of the major light-harvesting polypeptides affects the redox properties of PSII reaction centres. Radiolabeling studies in vivo and in vitro with [32P]orthophosphate or [gamma-32P]ATP, respectively, demonstrated that the D1 PSII reaction centre polypeptide is phosphorylated in both the WT and the F2 mutant. In contrast with the radiolabeling results, phosphorylation of D1 and other PSII proteins, although detected in WT barley, was ambiguous in the F2 mutant when the phosphothreonine antibody method of detection was used. Thus, caution must be exercised in the use of commercially available phosphothreonine antibodies to estimate thylakoid polypeptide phosphorylation. Furthermore, in membrano, the D1 polypeptide of the F2 mutant was less susceptible to trypsin treatment than that of WT barley. The role of the light-harvesting complex in modulating the structure and function of the D1 polypeptide of PSII reaction centers is discussed.

RAPD based genetic variability among cultivated varieties of Aonla (Indian Gooseberry, Phyllanthus emblica L.).

Aonla, the Indian Gooseberry (Phyllanthus emblica) is widely grown in India due to its neutraceutical properties. Investigations on the use of RAPD markers enabled us to estimate genetic variability among commercially cultivated varieties. This study also enabled us to distinguish these varieties using a set of four decamer primers, which was otherwise difficult by using morphological markers. Cluster analysis revealed three different groups of varieties directly associated to their place of origin. RAPD markers were also able to differentiate varieties of same origin or even selection from same parents. This information can be used for identification of varieties and further crop improvement programme.

The lack of LHCII proteins modulates excitation energy partitioning and PSII charge recombination in Chlorina F2 mutant of barley.

Analysis of the partitioning of absorbed light energy within PSII into fractions utilized by PSII photochemistry (ØPSII), thermally dissipated via ΔpH-and zeaxanthin-dependent energy quenching (ØNPQ) and constitutive non-photochemical energy losses (ØNO) was performed in wild type and F2 mutant of barley. The estimated energy partitioning of absorbed light to various pathways indicated that the fraction of ØPSII was slightly higher, while the proportion of thermally dissipated energy through ØNPQ was 38% lower in F2 mutant than in WT. In contrast, ØNO, i.e. the fraction of absorbed light energy dissipated by additional quenching mechanism(s) was 34% higher in F2 mutant. The increased proportion of ØNO correlated with narrowing the temperature gap (ΔT M) between S2/3QB- and S2QA- charge recombinations in F2 mutant as revealed by thermoluminescence measurements. We suggest that this would result in increased probability for an alternative non-radiative P680+QA- radical pair recombination pathway for energy dissipation within the reaction centre of PSII (reaction center quenching) and that this additional quenching mechanism might play an important role in photoprotection when the capacity for the primary, zeaxanthin-dependent non-photochemical quenching (ØNPQ) and state transitions pathways are restricted in the absence of LHCII polypeptides in F2 mutant.

Acclimation to temperature and irradiance modulates PSII charge recombination.

Acclimation of wild type and the chlorina F2 mutant of barley to either high light or low temperature results in a 2- to 3-fold increase in non-photochemical quenching which occurred independently of either energy-dependent quenching (qE), xanthophyll cycle-mediated antenna quenching or state transitions. Results of in vivo thermoluminescence measurements used to address this conundrum indicated that excitation pressure regulates the temperature gap for S(2)Q(B)(-) and S(2)Q(A)(-) charge recombinations within photosystem II reaction centers. This is discussed in terms of photoprotection through non-radiative charge recombination.

The oxygen-dependent deactivation and reactivation of spinach ribulose-1,5-bisphosphate carboxylase.

Ribulose-1,5-bisphosphate carboxylase-oxygenase (3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39) is deactivated by the removal of oxygen, and reversibly reactivated by its readdition to the enzyme solution. A short pulse of oxygen to the anaerobic enzyme solution is sufficient to trigger the reactivation process; the Ka value for this reaction was estimated as 0.12 mM oxygen. The enzyme could not be reactivated under anaerobic conditions by an organic oxidant (benzoylperoxide) or by sulfhydryl group reducing reagents (dithiothreitol or beta-mercaptoethanol), suggesting that the process of reactivation was oxygen specific. Furthermore, the inhibition of the reactivation by superoxide anion scavengers such as Tiron (1,2-dihydroxybenzene-3,5-disulfonic acid), copper penicillamine, hydroxylamine, nitroblue tetrazolium, and ascorbate, indicated that the monovalent reduced oxygen was involved as the reacting species in this process. The deactivation of the enzyme associated with the removal of oxygen was also sensitive to the presence of scavengers of O2(-), suggesting that superoxide anion was also involved in the deactivation process. Both the carboxylase and the oxygenase activities were similarly affected under all the experimental conditions studied. On the basis of these results it is argued that the enzyme molecules are able to reduce oxygen and that superoxide anion causes the deactivation or reactivation of the enzyme.

Essential histidyl residues at the active site(s) of sucrose-phosphate synthase from Prosopis juliflora.

Chemical modification of sucrose-phosphate synthase (EC 2.4.1.14) from Prosopis juliflora by diethyl pyrocarbonate (DEP) and photo-oxidation in the presence of rose bengal (RB) which modify the histidyl residues of the protein resulted in the inactivation of the enzyme activity. This inactivation was dependent on the concentration of the modifying reagent and the time of incubation and followed pseudo-first order kinetics. For both the reagents, the inactivation was maximum at pH 7.5, which is consistent with the involvement and presence of histidine residues at the active site of the enzyme. Substrates, UDPG and F6P protected the enzyme against the inactivation by the modifying reagents suggesting that the histidine residues may be involved in the binding of these substrates and are essential for the catalytic activity. Specificity of DEP was indicated by an increase in absorbance at 240 nm along with concomitant inactivation of the enzyme and reactivation of the modified enzyme by hydroxylamine. These results strongly suggest the presence of histidine residue(s) at or near the active site of the enzyme.

Characterization of the low temperature thermoluminescence band Zv in leaf: an explanation for its variable nature.

Out of the six thermoluminescence bands reported for a mature leaf, one band (Zv) appearing at the lowest temperatures is dependent on the temperature of illumination. The characteristics of this band in fresh leaf are compared with those is a leaf heated to 60 degrees C for 5 min. It is concluded here that this band, following illumination at temperatures lower than 173 K, is part of Arnold and Azzi's Z band (Arnold, W. and Azzi, J.R. (1971) Photochem. Photobiol. 14, 233--240). However, it is part of peak I when observed subsequent to illumination beyond 173 K. An explanation for the appearance of this band at different temperatures is proposed.

Photoinhibition of photosystem I in a pea mutant with altered LHCII organization.

Comparative analysis of in vivo chlorophyll fluorescence imaging revealed that photosystem II (PSII) photochemical efficiency (Fv/Fm) of leaves of the Costata 2/133 pea mutant with altered pigment composition and decreased level of oligomerization of the light harvesting chlorophyll a/b-protein complexes (LHCII) of PSII (Dobrikova et al., 2000; Ivanov et al., 2005) did not differ from that of WT. In contrast, photosystem I (PSI) activity of the Costata 2/133 mutant measured by the far-red (FR) light inducible P700 (P700(+)) signal exhibited 39% lower steady state level of P700(+), a 2.2-fold higher intersystem electron pool size (e(-)/P700) and higher rate of P700(+) re-reduction, which indicate an increased capacity for PSI cyclic electron transfer (CET) in the Costata 2/133 mutant than WT. The mutant also exhibited a limited capacity for state transitions. The lower level of oxidizable P700 (P700(+)) is consistent with a lower amount of PSI related chlorophyll protein complexes and lower abundance of the PsaA/PsaB heterodimer, PsaD and Lhca1 polypeptides in Costata 2/133 mutant. Exposure of WT and the Costata 2/133 mutant to high light stress resulted in a comparable photoinhibition of PSII measured in vivo, although the decrease of Fv/Fm was modestly higher in the mutant plants. However, under the same photoinhibitory conditions PSI photochemistry (P700(+)) measured as ΔA820-860 was inhibited to a greater extent (50%) in the Costata 2/133 mutant than in the WT (22%). This was accompanied by a 50% faster re-reduction rate of P700(+) in the dark indicating a higher capacity for CET around PSI in high light treated mutant leaves. The role of chloroplast thylakoid organization on the stability of the PSI complex and its susceptibility to high light stress is discussed.

Rupture of intracranial aneurysm during computerized tomography.

A computerized tomographic (CT) scan was performed on a patient with a suspected paraseller mass. Coincident with contrast injection, an unusual and distinctive "starburst" pattern appeared in the right parasellar region and was associated with sudden deterioration in the patient's condition. Subsequent CT and necropsy confirmed a ruptured aneurysm at the suspected site with a large subarachnoid hemorrhage. To our knowledge, this unusual CT picture of a rupturing intracranial aneurysm has not been previously illustrated.

Collagenase in the treatment of dermal and decubitus ulcers.

The current management of decubitus ulcers, factors in wound healing and the role of enzymes in treatment are discussed. The therapeutic benefits of collagenase (Santyl) ointment in 21 patients are described, supplemented by serial color photographs. Statistical evidence is provided for the conclusion that collagenase ointment is an excellent adjunct to therapy.

Molecular cloning of Indian tomato leaf curl virus genome following a simple method of concentrating the supercoiled replicative form of viral DNA.

DNA-A and DNA-B components of the genome of a whitefly transmitted virus causing yellowing and leaf curl in tomato (ITLCV) were cloned following a simple procedure for isolation of the double stranded replicative form of viral DNA from infected tomato plants. The method is based on extraction of total DNA from infected plants followed by concentration of the double stranded replicative form of viral DNA by an alkaline denaturation procedure identical to that used for isolation of plasmid DNA from Escherichia coli. The attempted cloning of DNA showed that 95% of the transformants contained plasmids with an insert of either DNA-A (2.75 kb) or DNA-B (2.55 kb). Cloned DNA-A and DNA-B when used as probes could detect DNA-A/DNA-B in total nucleic acid obtained from fresh diseased tissue. Both DNA-A and DNA-B are needed for infection and they have a common region of 166 bases with about 94% nucleotide sequence homology, a characteristic of all bipartite geminiviruses. Comparison of the amino acid sequence of the putative coat protein product of ITLCV with some other mono- and bipartite geminiviruses revealed a maximum of 86% homology with Indian cassava mosaic virus.

Computed tomography of primitive neuroectodermal tumors.

The primitive neuroectodermal tumor is a neoplasm of young individuals that occurs predominantly in the supratentorial compartment. It appears on computed tomography as a bulky mass, often with calcification with predominantly homogeneous enhancement but on occasion with cystic or necrotic areas. Cerebrospinal fluid seeding was observed in more than half the cases in our series. The patients had a short survival period (7-24 months). Despite surgery, radiation, and chemotherapy, further growth of this tumor has not been prevented.

Computed tomography of the anteverted internal auditory canal.

A symmetric variation in the course of the internal auditory canals, visualized best on axial computed tomographic views with thin sections, was observed in three of 75 patients examined mainly for hearing, vestibular, and facial nerve dysfunction. The incidence may be lower in an unselected population. In coronal section, with either pluridirectional or computed tomography, an anteverted internal auditory canal may mimic the normal configuration of "medial narrowing" because of the effect of partial sectioning of an angled cylinder with a thin beam. The pathologic significance of this finding is uncertain. In the three cases reported, it was associated with adult-onset uni- or bilateral hearing loss. Vestibular function may be compromised but may not be symptomatic. Facial nerve function was not impaired.

Patterns of spinal cord atrophy by metrizamide CT.

Forty patients with cervical myelopathy underwent high-resolution computed tomography (CT) with intrathecal administration of metrizamide for evaluation of cervical spinal cord atrophy. Thirty of them showed evidence of either focal atrophic distortion or generalized accentuation of the anatomic surface features of the spinal cord. Patients with a Chiari malformation or syringomyelia were excluded. The characteristic features in cervical spondylosis and canal deformity include flattening of the ventral surface of the cord, central infolding, beaking of the lateral funiculi, and wasting of the dorsal surface of the cord. Patients with motor neuron disease showed a combination of anterolateral and posterolateral atrophy reflecting underlying degeneration of the anterior horn cells and/or corticospinal tracts, respectively. Those with monomelic motor neuron disease had a striking ipsilateral hemiatrophy of the spinal cord. Among those presenting with spastic paraparesis, seven with clinically definite multiple sclerosis showed diffuse atrophy or focal degeneration due to a localized plaque of demyelination. Two cases of cord neoplasm showed atrophy secondary to ascending or descending degeneration of the long tracts.

Computed tomography of the cervical lymph nodes: use of intravenous contrast enhancement.

Intravenous contrast administration increases the sensitivity of computed tomographic scanning for enlarged cervical lymph nodes but requires a detailed knowledge of neck anatomy, especially in order to distinguish certain normal vessels from involved nodal groups. Along the collar chain, relations between the parotid and submandibular salivary glands and the posterior and anterior facial veins and facial artery are analyzed. The digastric muscle is defined as a transitional landmark between collar and deep cervical nodes. Along the deep cervical chain, emphasis is on the internal jugular vein, its variability in size, and its relations to the anterior scalene and omohyoid muscles.

In vivo NMR imaging of tissue sodium in the intact cat before and after acute cerebral stroke.

The first in vivo nuclear magnetic resonance (NMR) images of tissue sodium in the intact animal are presented. The distribution of sodium in the normal cat's head is described. An experimental stroke was surgically induced. Sodium NMR imaging showed a pronounced focal increase in cerebral sodium concentration 9 hr after ligation of the middle cerebral artery. The method appears to be very sensitive for early detection of infarction. The measured increase in the regional sodium NMR signal probably reflects both a true increase in concentration of brain sodium and an increased NMR visibility of the sodium nucleus in the region of the infarction.

CT of the nasopharyngeal region. Normal and pathologic anatomy.

The soft tissue anatomy of the nasopharynx is presented in terms of deglutitional and masticatory muscle layers. Within this framework of analysis, computed tomography can detect relatively early soft tissue changes of nasopharyngeal carcinoma.

Leaf Curl Disease of Carica papaya from India May Be Caused by a Bipartite Geminivirus.

Papaya has considerable economic importance to agriculture in India. Papaya leaf curl disease was first reported in 1939 by Thomas and Krishnaswamy (3). This disease is of moderate incidence and widely distributed in India. Recent observations of papaya fields in India indicated that there has been a continued increase in the incidence of papaya leaf curl disease (as shown by symptoms), resulting in severe economic losses. The disease is characterized by downward curling and cupping of leaves followed by vein clearing and thickening. Enations develop in the form of frills on green veins. The affected leaves become leathery and brittle and the petioles become twisted in a zig-zag manner. Diseased plants may bear a few small fruits, which are distorted in shape and tend to fall prematurely. The disease could be transmitted by the whitefly Bemisia tabaci Genn. Therefore, possible involvement of a geminivirus was suspected. Three different cloned geminiviral DNAs, Indian tomato leaf curl virus (ITLCV) (2), tomato yellow leaf curl virus from Sardinia (TYLCV Sar), and tomato golden mosaic virus (TGMV), were used as probes (with radioactive labeling) to detect the presence of geminiviral DNA from infected papaya tissue in both slot-blot and Southern blot hybridization studies with high stringency washes. These DNA probes gave strong signals with DNA isolated from infected papaya tissue whereas they did not give any signals with DNA from healthy tissue. Further, successful polymerase chain reaction (PCR)-based amplification of fragments from both DNA-A and DNA-B components with geminivirus degenerate primers (1) was accomplished only from the DNA of infected papaya plants. The PCR-amplified DNA fragments gave positive signals in Southern blot hybridization with the three geminiviral DNA probes. These results suggest that the causal agent of papaya leaf curl disease is a bipartite geminivirus that may be provisionally called papaya leaf curl virus (PLCV). References: (1) M. R. Rojas et al. Plant Dis. 77:340, 1993. (2) K. M. Srivastava et al. J. Virol. Methods 51:297, 1995. (3) K. M. Thomas and C. S. Krishnaswamy. Curr. Sci. 8:316, 1939.