Deciphering the role of various cis-acting regulatory elements in controlling SamDC gene expression in rice

Lately we have published on the characterization of the upstream of SamDC gene from rice and investigated the involvement of various cis-elements present in the promoter region in its transcriptional regulation. Analysis of SamDC expression showed that it was inducible by abiotic stresses like salinity, drought, and cold as well as by light and ABA treatment. Furthermore, DNA protein interaction studies have identified transacting actors responsible for its expression after abiotic stresses or light inducibility. Here we have further discussed on the possible role of these cis-elements in modulating the transcriptional network and comment on their function in relation to polyamine biosynthesis during periods of abiotic stress in rice.

Identification of trans-acting factors regulating SamDC expression in Oryza sativa

Abiotic stress affects the growth and productivity of crop plants; to cope with the adverse environmental conditions, plants have developed efficient defense machinery comprising of antioxidants like phenolics and flavonoids, and osmolytes like polyamines. SamDC is a key enzyme in the polyamine biosynthesis pathway in plants. In our present communication we have done in silico analysis of the promoter region of SamDC to look for the presence of different cis-regulatory elements contributing to its expression. Based on the presence of different cis-regulatory elements we completed comparative analysis of SamDC gene expression in rice lamina of IR-29 and Nonabokra by qPCR in response to the abiotic stress treatments of salinity, drought, cold and the biotic stress treatments of ABA and light. Additionally, to explore the role of the cis-regulatory elements in regulating the expression of SamDC gene in plants we comparatively analyzed the binding of rice nuclear proteins prepared from IR-29 and Nonabokra undergoing various stress treatments. The intensity of the complex formed was low and inducible in IR-29 in contrast to Nonabokra. Southwestern blot analysis helped in predicting the size of the trans-acting factors binding to these cis-elements. To our knowledge this is the first report on the comprehensive analysis of SamDC gene expression in rice and identification of the trans-acting factors regulating its expression.

Involvement of AtPolλ in the repair of high salt- and DNA cross-linking agent-induced double strand breaks in Arabidopsis

DNA polymerase λ (Pol λ) is the sole member of family X DNA polymerase in plants and plays a crucial role in nuclear DNA damage repair. Here, we report the transcriptional up-regulation of Arabidopsis (Arabidopsis thaliana) AtPolλ in response to abiotic and genotoxic stress, including salinity and the DNA cross-linking agent mitomycin C (MMC). The increased sensitivity of atpolλ knockout mutants toward high salinity and MMC treatments, with higher levels of accumulation of double strand breaks (DSBs) than wild-type plants and delayed repair of DSBs, has suggested the requirement of Pol λ in DSB repair in plants. AtPolλ overexpression moderately complemented the deficiency of DSB repair capacity in atpolλ mutants. Transcriptional up-regulation of major nonhomologous end joining (NHEJ) pathway genes KU80, X-RAY CROSS COMPLEMENTATION PROTEIN4 (XRCC4), and DNA Ligase4 (Lig4) along with AtPolλ in Arabidopsis seedlings, and the increased sensitivity of atpolλ-2/atxrcc4 and atpolλ-2/atlig4 double mutants toward high salinity and MMC treatments, indicated the involvement of NHEJ-mediated repair of salinity- and MMC-induced DSBs. The suppressed expression of NHEJ genes in atpolλ mutants suggested complex transcriptional regulation of NHEJ genes. Pol λ interacted directly with XRCC4 and Lig4 via its N-terminal breast cancer-associated C terminus (BRCT) domain in a yeast two-hybrid system, while increased sensitivity of BRCT-deficient Pol λ-expressing transgenic atpolλ-2 mutants toward genotoxins indicated the importance of the BRCT domain of AtPolλ in mediating the interactions for processing DSBs. Our findings provide evidence for the direct involvement of DNA Pol λ in the repair of DSBs in a plant genome.

C-terminal phosphorylation is essential for regulation of ethylene synthesizing ACC synthase enzyme

The genetic and molecular biological studies mainly in Arabidopsis and in some other plants have begun to uncover the various components of ripening signaling pathway in plants. Although transcriptional regulation of major ripening genes have been studied in detail, information on role of phosphorylation in regulating the activity and stability of core ripening pathway associated proteins in relation to ethylene biosynthesis during fruit ripening is still limited. Recently we have demonstrated the evidence for post-translational regulation of MA-ACS1 (Musa acuminata ACC synthase 1), the rate limiting step enzyme regulating ripening ethylene production in banana, through phosphorylation at the C-terminal Ser 476 and 479 residues by a 41-kDa Ser/Thr protein kinase. (1) Here we have further discussed role of protein phosphorylation in regulation of stability and activity of ACS enzymes and the mechanistic and evolutionary perspective of phosphorylation pattern of Type I ACC synthase enzymes.

A Ser/Thr protein kinase phosphorylates MA-ACS1 (Musa acuminata 1-aminocyclopropane-1-carboxylic acid synthase 1) during banana fruit ripening

1-Aminocyclopropane-1-carboxylic acid synthase (ACS) catalyzes the rate-limiting step in ethylene biosynthesis during ripening. ACS isozymes are regulated both transcriptionally and post-translationally. However, in banana, an important climacteric fruit, little is known about post-translational regulation of ACS. Here, we report the post-translational modification of MA-ACS1 (Musa acuminata ACS1), a ripening inducible isozyme in the ACS family, which plays a key role in ethylene biosynthesis during banana fruit ripening. Immunoprecipitation analyses of phospholabeled protein extracts from banana fruit using affinity-purified anti-MA-ACS1 antibody have revealed phosphorylation of MA-ACS1, particularly in ripe fruit tissue. We have identified the induction of a 41-kDa protein kinase activity in pulp at the onset of ripening. The 41-kDa protein kinase has been identified as a putative protein kinase by MALDI-TOF/MS analysis. Biochemical analyses using partially purified protein kinase fraction from banana fruit have identified the protein kinase as a Ser/Thr family of protein kinase and its possible involvement in MA-ACS1 phosphorylation during ripening. In vitro phosphorylation analyses using synthetic peptides and site-directed mutagenized recombinant MA-ACS1 have revealed that serine 476 and 479 residues at the C-terminal region of MA-ACS1 are phosphorylated. Overall, this study provides important novel evidence for in vivo phosphorylation of MA-ACS1 at the molecular level as a possible mechanism of post-translational regulation of this key regulatory protein in ethylene signaling pathway in banana fruit during ripening.

Overexpression of Rab16A gene in indica rice variety for generating enhanced salt tolerance

We report here the overexpression of Rab16A full length gene (promoter + ORF), from the salt-tolerant indica rice Pokkali, in the salt-susceptible indica rice variety Khitish, via particle bombardment. Molecular analysis of the transgenics revealed stable integration of the transgene upto T2 generation. High level of expression of the transgene (driven by its own stress-inducible promoter), as well as the protein, was detectable in the leaves under simulated salinity stress (250 mM NaCl, 24 h); the expression level being higher than wild type (WT) plants. The Rab16A transcript also increased gradually with seed maturity, with its maximal accumulation at 30 d after pollination (DAP) i.e., fully matured seeds, explaining the protective role of Rab16A gene during seed maturation. Enhanced tolerance to salinity was observed in the plants transformed with Rab16A. The superior physiological performances of the transgenics under salt treatment were also reflected in lesser shoot or root length inhibition, reduced chlorophyll damages, lesser accumulation of Na(+) and reduced loss of K(+), increased proline content as compared with the WT plants. All these results indicated that the overproduction of RAB16A protein in the transgenics enable them to display enhanced tolerance to salinity stress with improved physiological traits. Our work demonstrates the profound potential of Group 2 LEA proteins (to which RAB16A belongs to) in conferring stress tolerance in crop plants through their genetic manipulation.

Carbohydrate content and antioxidative potential of the seed of three edible indica rice (Oryza sativa L.) cultivars

Rice (Oryza sativa L.) grains or seeds are known to lose much of their nutrient and antioxidant contents, following polishing. The current study was undertaken to evaluate and compare the carbohydrate content and antioxidant parameters in the unpolished and polished seeds of three edible indica rice cultivars, namely Swarna (SW), the most popular indica rice cultivar in India and aromatic or scented cultivars Gobindobhog (GB) and Pusa Basmati (PB). While both the sucrose and starch content was the maximum in PB seeds (both unpolished and polished), the amylose content was the highest in SW polished seeds. SW polished seeds were superior as compared to GB and PB cultivars in terms of total antioxidant capacity, DPPH radical scavenging and Fe(II) chelation potential, as well as the highest lipoxygenase (LOX) inhibition or H2O2 scavenging potential, probably due to the maximum accumulation of total phenolics and flavonoids, the two important antioxidants. The reducing power ability was, however, identical in both SW and GB polished seeds. The PB polished seeds were more potent in superoxide and hydroxyl scavenging, whereas GB in nitric oxide (NO) scavenging. The common observation noted after polishing of seeds was the reduction in the level of carbohydrates and antioxidant potential, though the extent of reduction varied in the three cultivars. The only exception was GB, where there was no alteration in NO scavenging potential even after polishing. Our study showed the better performance of SW polished seeds with respect to higher amylose content and majority of the tested parameters governing antioxidant capacity and radical scavenging potential, thus highlighting the greater dietary significance of SW over the other two cultivars.

Inducibility of three salinity/abscisic acid-regulated promoters in transgenic rice with gusA reporter gene

The present study evaluates the pattern of stress inducibility of one natural promoter (from rice Rab16A) and two synthetically designed promoters, viz., 4X ABRE (abscisic acid-responsive element, having four tandem repeats of ABRE) and 2X ABRC (abscisic acid-responsive complex, having two tandem repeats of ABRE and two copies of coupling elements), in response to varying concentrations of NaCl and abscisic acid (ABA). Each promoter, independently linked to gusA (that encodes β glucuronidase, GUS), was introduced into rice (cv. Khitish) through particle bombardment. The T(2) progenies showed integration of gusA in their genome. The accumulation of gusA transcript, driven by each promoter in T(2) transgenics, increased with increasing salt/ABA concentration, with ABA being the better activator of each promoter. Induction in GUS expression, driven by different promoters, was noted on exogenous salt/ABA treatments in a concentration-dependent manner. The maximum induction was observed with 2X ABRC promoter. All the three promoters could drive stress-inducible GUS expression in both vegetative and floral organs. However, prominent GUS expression was noted in the whole seed (both embryo and aleurone layer of endosperm) only by 2X ABRC, whereas it was localized only in the embryo for the other two promoters. Thus, our observation characterizes three efficient salinity/ABA-inducible promoters that have the potentiality in crop biotechnology to drive transgene expression for stress tolerance, whenever abiotic stress is encountered.

Amelioration of salinity stress by exogenously applied spermidine or spermine in three varieties of indica rice differing in their level of salt tolerance

We present here the comparative protective potentiality of exogenously applied polyamines (PAs), namely spermidine (Spd) and spermine (Spm), in mitigating NaCl toxicity and inducing short-term salinity tolerance in three indica rice varieties, namely M-1-48 (salt-sensitive), Nonabokra (salt-tolerant) and Gobindobhog (highly sensitive). The retardation in root length or shoot length and toxic Na(+) accumulation or K(+) loss, the considerable increment in malondialdehyde/H(2)O(2) accumulation or lipoxygenase activity, all of which were particularly noteworthy in M-1-48 and Gobindobhog during salinity stress, was appreciably reduced by co-treatment with Spd or Spm. Both the PAs also inhibited the extent of salt-induced protein carbonylation in all the varieties and enhanced protease activity, especially in Gobindobhog. The prevention of chlorophyll degradation was better with Spd in Nonabokra and Gobindobhog. While the salt-induced increase in anthocyanin or reducing sugar level was further prompted by Spd or Spm in all the varieties, the proline content was elevated by Spd particularly in Gobindobhog. During salinity stress, both the PAs were effective in lowering the putrescine accumulation in M-1-48 and Gobindobhog, and strikingly increasing the Spm level in all the varieties, the highest being in Gobindobhog. In addition, they enhanced the activity of peroxidases and compensated for the decreased catalase activity in all the varieties. Thus the two PAs could recuperate all the three varieties from salt-induced damages to different degrees. The salt injuries, encountered in M-1-48 and Gobindobhog, both of which showed greater susceptibility to salinity stress, were more pronouncedly alleviated and counteracted by the PAs, than the salt-tolerant Nonabokra. The reversal of inhibitory effect of salinity stress was conferred by preventing growth inhibition or various forms of cellular damages, maintaining proper K(+)/Na(+) balance or triggering the level of osmolytes and activity of antioxidant enzymes. Our communication offers a referenced evidence for an understanding of the mechanism by which higher PAs relieve the damages particularly in salt-sensitive rice varieties.

Understanding DNA repair and recombination in higher plant genome: information from genome-wide screens in Arabidopsis and rice

Recently we have reported the in silico identification and in depth analysis of genes potentially involve in DNA repair and recombination (DRR) in two fully sequenced higher plant genomes, Arabidopsis and rice. In spite of strong conservation of DRR gene along with all three domain of life, we found some peculiar difference in presence and function of DRR genes in plants. Beside the eukaryotic homologs, several prokaryotes specific genes were also found to be well conserved in both plant genomes. Several functionally important DRR gene duplications were found in Arabidopsis, which do not occur in rice. In spite of the fact that same DRR protein functions in different DNA repair pathways, we found that proteins belonging to the nucleotide excision repair (NER) pathway were relatively more conserved than proteins needed for the other DRR pathways. Identified DRR gene were found to reside in nucleus mainly while gene drain in between nucleus and cell organelles were also found in some cases. Here, we have discussed the peculiar features of DRR genes in higher plant genomes.

Molecular characterization and differential expression of beta-1,3-glucanase during ripening in banana fruit in response to ethylene, auxin, ABA, wounding, cold and light-dark cycles

beta-1,3-Glucanases (E.C. 3.2.1.39) are widely distributed enzyme among bacteria, fungi, and higher plants. Analyses of accumulation levels of beta-1,3-glucanase protein in various tissues in banana have clearly indicated abundance of beta-1,3-glucanase protein accumulation in ripe pulp tissue. After cloning of beta-1,3-glucanase from banana pulp (cultivar Cavendish), we have carried out an in silico analysis to investigate the sequential, structural, and phylogenetic characteristics of the putative banana beta-1,3-glucanase protein. As like other ripening specific genes, beta-1,3-glucanase is regulated in response to a wide variety of factors. Therefore, we have analyzed the transcript accumulation pattern and protein levels of beta-1,3-glucanase in response to ethylene, auxin, ABA, wounding and, low temperature in preclimacteric banana fruit. Expression profile analyses have indicated that whereas exogenous application of ethylene strongly stimulated beta-1,3-glucanase transcript accumulation, ABA partially induced the expression of the gene. On the other hand, wound treatment did not induce beta-1,3-glucanase expression. Conversely, auxin and cold treatment negatively regulated beta-1,3-glucanase gene expression and thus inhibited glucanase activity. In addition, beta-1,3-glucanase transcript level was markedly decreased by constant exposure to white light. Protein level and enzymatic activity of beta-1,3-glucanase were substantially increased with considerable decrease in fruit firmness by ethylene treatment and reduced exposure to white light conditions as compared with other treatments. Together, the overall study of beta-1,3-glucanase expression pattern, glucanase activity, and changes in fruit firmness during ripening in various conditions suggest the possible physiological function of beta-1,3-glucanase in fruit pulp softening.

DNA repair and recombination in higher plants: insights from comparative genomics of Arabidopsis and rice

Background

The DNA repair and recombination (DRR) proteins protect organisms against genetic damage, caused by environmental agents and other genotoxic agents, by removal of DNA lesions or helping to abide them.

Results

We identified genes potentially involved in DRR mechanisms in Arabidopsis and rice using similarity searches and conserved domain analysis against proteins known to be involved in DRR in human, yeast and E. coli. As expected, many of DRR genes are very similar to those found in other eukaryotes. Beside these eukaryotes specific genes, several prokaryotes specific genes were also found to be well conserved in plants. In Arabidopsis, several functionally important DRR gene duplications are present, which do not occur in rice. Among DRR proteins, we found that proteins belonging to the nucleotide excision repair pathway were relatively more conserved than proteins needed for the other DRR pathways. Sub-cellular localization studies of DRR gene suggests that these proteins are mostly reside in nucleus while gene drain in between nucleus and cell organelles were also found in some cases.

Conclusions

The similarities and dissimilarities in between plants and other organisms' DRR pathways are discussed. The observed differences broaden our knowledge about DRR in the plants world, and raises the potential question of whether differentiated functions have evolved in some cases. These results, altogether, provide a useful framework for further experimental studies in these organisms.

Understanding the molecular mechanism of transcriptional regulation of banana Sucrose phosphate synthase (SPS) gene during fruit ripening: an insight into the functions of various cis-acting regulatory elements

Recently, we have reported the characterization of promoter region of Sucrose phosphate synthase (SPS) gene in banana and investigated the role of some cis-elements/motifs, present in the promoter of SPS, in the transcriptional regulation of the gene. DNA-protein interaction studies have demonstrated the presence of specific trans-acting factors which showed specific interactions with ethylene, auxin, low temperature and light responsive elements in regulating SPS transcription. Transient expression analyses have demonstrated the functional significance of the various cis-acting regulatory elements present in banana SPS promoter in regulating SPS expression during ripening. (1) Here, we have further discussed the possible role of these regulatory sequences in the regulation of transcriptional network and comment on their function in relation to sucrose metabolism during banana fruit ripening.

Characterization of cultivar differences in beta-1,3 glucanase gene expression, glucanase activity and fruit pulp softening rates during fruit ripening in three naturally occurring banana cultivars

beta-1,3 glucanase (E.C.3.2.1.39) is the key enzyme involved in the hydrolytic cleavage of 1,3 beta-D glucosidic linkages in beta-1,3 glucans. This work describes a comparative analysis of expression patterns of beta-1,3 glucanase gene in relation to changes in fruit pulp softening rates in three banana cultivars, Rasthali (AAB), Kanthali (AB), and Monthan (ABB). Analysis of transcript and protein levels of beta-1,3 glucanase gene during ripening revealed differential timing in expression of the gene which correlated well with the variation in enzymatic activity of glucanase and fruit pulp softening rates in the three cultivars. Exogenously applied ethylene strongly induced beta-1,3 glucanase expression during the early ripening days in Rasthali, while the expression of the gene was marginally stimulated following ethylene treatment in preclimacteric Kanthali fruit. Conversely, in Monthan, beta-1,3 glucanase expression was very low throughout the ripening stages, and ethylene treatment did not induce the expression of the gene in this cultivar. Analysis of glucanase activity using protein extracts from unripe and ripe fruit of Monthan with crude cell wall polysaccharide fractions (used as substrate) indicated that the natural substrate for glucanase remained almost unutilized in this cultivar due to low in vivo glucanase activity. Furthermore, the recombinant beta-1,3 glucanase protein, overexpressed in E. coli, showed requirement for substrates with contiguous beta-1,3 linkages for optimal activity. Overall, our results provide new information on the expression profile of beta-1,3 glucanase gene in connection with the pattern of changes in fruit firmness at the physiological and molecular levels during ripening in three banana cultivars.

Comparative expression of two abscisic acid-inducible genes and proteins in seeds of aromatic indica rice cultivar with that of non-aromatic indica rice cultivars

As an integral part of stress signal transduction, the phytohormone abscisic acid (ABA) regulates important cellular reactions, including up-regulation of stress-associated genes, the products of which are involved directly or indirectly in plant protection. Being accompanied by an increased endogenous ABA level, the matured seeds, embryo and aleurone tissues of cereals accumulate several genes and proteins, associated with desiccation. The present study was aimed at investigating how the contrasting rice genotypes, varying in their salt-stress sensitivity, differ with respect to the expression pattern of two abiotic stress-inducible genes, Rab16A and SamDC, and corresponding proteins, in the seeds, at the background level (dry or water-imbibed state) and ABA-imbibed conditions, which could be related to the varietal differences in tolerance. The rice genotypes selected were M-1-48 (salt-sensitive), Nonabokra (salt-tolerant) and Gobindobhog (aromatic). An extremely low abundance of Rab16A or practically undetectable SamDC transcripts were observed in M-1-48 and Gobindobhog seeds under control conditions, induced only after exogenous ABA treatment, whereas they were expressed at a much higher level even in dry and water-imbibed seeds of Nonabokra, and lesser induced by ABA. The RAB16A (=dehydrin) and SAMDC protein expression in the three varieties were also identical to the gene expression patterns. Thus, the expression was stress-inducible in M-1-48 and Gobindobhog, while constitutive in Nonabokra. Our study reflected the similarity of the molecular responses to exogenous ABA of the seeds of the aromatic rice Gobindobhog to that of the salt-sensitive M-1-48, in exhibiting lower expression of stress-tolerant proteins only after stress. This work also proved that variation in gene/protein expression in seeds could be highly correlated with the variation in the tolerance mechanism of rice varieties.

Analysis of comparative efficiencies of different transformation methods of E. coli using two common plasmid vectors

The efficiencies of different transformation methods of E. coli DH5Qalpha train, induced by several cations like Mg2+, Mn2+ Rb+ and especially Ca2+, with or without polyethylene glycol (PEG) and dimethyl sulfoxide (DMSO) were compared using the two commonly used plasmid vectors pCAMBIA1201 and pBI121. The widely used calcium chloride (CaCl2) method appeared to be the most efficient procedure, while rubidium chloride (RbCl) method was the least effective. The improvements in the classical CaCl2 method were found to further augment the transformation efficiency (TR)E for both the vectors like repeated alternate cycles of heat shock, followed by immediate cold, at least up to the third cycle; replacement of the heat shock step by a single microwave pulse and even more by double microwave treatment and administration of combined heat shock-microwave treatments. The pre-treatment of CaCl2-competent cells with 5% (v/v) ethanol, accompanied by single heat shock also triggered the (TR)E, which was further enhanced, when combined heat shock-microwave was applied. The minor alterations or improved approaches in CaCl2 method suggested in the present study may thus find use in more efficient E. coli transformation.

An insight into the biological functions of family X-DNA polymerase in DNA replication and repair of plant genome

Recently we have reported the characterization of a novel single subunit 62-kDa polypeptide with ddNTP-sensitive DNA polymerase activity from the developing seeds of mungbean (Vigna radiata). The protein showed higher expression and activity level during nuclear endoreduplication stages of mungbean seeds and similarity with mammalian DNA polymerase beta in many physicochemical properties. The enzyme was found to specifically interact with PCNA (proliferating cell nuclear antigen), and expressed in both meristematic and meiotic tissues. Functional assays have demonstrated binding of the enzyme to normal and mismatched DNA substrates and with fidelity DNA synthesis in moderately processive mode, suggesting probable involvement of the enzyme in both replication and recombination. Here we have discussed the position of mungbean DNA polymerase as a homologue of DNA Pol lambda, one of the newly identified member of family-X DNA polymerase in plants and illustrated the functional relevance of this enzyme in maintaining the coordination between DNA replication and repair in plant genome.

Characterization of transcriptional profiles of MA-ACS1 and MA-ACO1 genes in response to ethylene, auxin, wounding, cold and different photoperiods during ripening in banana fruit

The ripening-specific genes MA-ACS1 (Musa acuminata ACC synthase1) and MA-ACO1 (M. acuminata ACC oxidase 1) are regulated in response to a wide variety of factors. Here, we have studied the differential transcript accumulation pattern and protein levels of MA-ACS1 and MA-ACO1 genes in response to ethylene, auxin, wounding and low temperature in preclimacteric banana fruit. We have shown that exogenous application of ethylene and auxin induced the expression of MA-ACS1, while MA-ACO1 showed marginal expression following ethylene treatment in preclimacteric stage. Auxin did not induce MA-ACO1 expression. Thus, auxin-treated banana fruits showed lower ethylene production rate as compared to ethylene-treated fruits. Conversely, wounding and cold treatment down-regulated the expression of both the genes and thus inhibited ethylene production. Furthermore, we have detected a GCC-box putative ethylene-responsive element (ERE)- and an auxin-responsive element (ARE)-specific DNA-binding activity in the banana pulp and studied the ethylene and auxin responsive characteristics of the GCC-box and ARE (TGTCTC) containing synthetic promoter fragments. In addition, we have detected an enhanced ethylene production rate and expression level of MA-ACS1 and MA-ACO1 genes along with a strong GCC-box-specific DNA-binding activity following exposure to constant dark period for 8d at the preclimacteric stage. Together, our study provides interesting information about the regulation of expression of MA-ACS1 and MA-ACO1 genes in response to various factors during ripening in banana fruit, which may have physiological relevance concerning ethylene biosynthesis during post-harvest conditions.

Differential transcriptional regulation of banana sucrose phosphate synthase gene in response to ethylene, auxin, wounding, low temperature and different photoperiods during fruit ripening and functional analysis of banana SPS gene promoter

Sucrose phosphate synthase (SPS) (EC 2.3.1.14) is the key regulatory component in sucrose formation in banana (Musa acuminata subgroup Cavendish, cv Giant governor) fruit during ripening. This report illustrates differential transcriptional responses of banana SPS gene following ethylene, auxin, wounding, low temperature and different photoperiods during ripening in banana fruit. Whereas ethylene strongly stimulated SPS transcript accumulation, auxin and cold treatment only marginally increased the abundance of SPS mRNA level, while wounding negatively regulated SPS gene expression. Conversely, SPS transcript level was distinctly increased by constant exposure to white light. Protein level, enzymatic activity of SPS and sucrose synthesis were substantially increased by ethylene and increased exposure to white light conditions as compared to other treatments. To further study the transcriptional regulation of SPS in banana fruit, the promoter region of SPS gene was cloned and some cis-acting regulatory elements such as a reverse GCC-box ERE, two ARE motifs (TGTCTC), one LTRE (CCGAA), a GAGA-box (GAGA...) and a GATA-box LRE (GATAAG) were identified along with the TATA and CAAT-box. DNA-protein interaction studies using these cis-elements indicated a highly specific cis-trans interaction in the banana nuclear extract. Furthermore, we specifically studied the light responsive characteristics of GATA-box containing synthetic as well as native banana SPS promoter. Transient expression assays using banana SPS promoter have also indicated the functional importance of the SPS promoter in regulating gene expression. Together, these results provide insights into the transcriptional regulation of banana SPS gene in response to phytohormones and other environmental factors during fruit ripening.

Comparative physiological and molecular responses of a common aromatic indica rice cultivar to high salinity with non-aromatic indica rice cultivars

In an attempt to understand the molecular basis of salt-stress response in the aromatic rice Gobindobhog, a comprehensive analysis encompassing physiological or biochemical assays and gene expression studies under high salt (200 mM NaCl) supply regimes were initiated and compared with a salt-sensitive (M-1-48) and salt-tolerant (Nonabokra) rice. The detrimental effects of salinity stress were the most pronounced in Gobindobhog, as reflected by the maximally increased root to shoot ratio, the highest chlorophyll degeneration, the highest foliar concentration of Na(+) ions and peroxide content, with their maximum increment after salt treatment. The amplification of oxidative damages was further stimulated by the accumulation of putrescine and lipid peroxidation-derived toxic degradation products (increased malondialdehyde and lipoxygenase activity), which were comparable in M-1-48 and Gobindobhog. Antioxidants like anthocyanin and particularly cysteine and the osmolytes like reducing sugar, proline and polyamines (spermidine and spermine) showed the highest level in Nonabokra. While the inhibition of catalase activity occurred in all the varieties following salt-stress, the maximum induction in guaiacol peroxidase activity, elevated cysteine and proline levels in Gobindobhog probably constituted the detoxification mechanism obligatory for its survival. Intensification of the aroma content with salt treatment was markedly noted in Gobindobhog. A very low abundance of Rab16A/SamDC transcript and the corresponding proteins were observed both in M-1-48 and Gobindobhog, induced only after salt-stress, whereas they were constitutively expressed in Nonabokra. Thus, our data reflect Gobindobhog as a salt-sensitive cultivar, susceptible to high-stress-induced growth-inhibition, ion imbalances, membrane/oxidative damages with lower expression of stress-tolerant genes.

Characterization of differential ripening pattern in association with ethylene biosynthesis in the fruits of five naturally occurring banana cultivars and detection of a GCC-box-specific DNA-binding protein

MA-ACS1 and MA-ACO1 are the two major ripening genes in banana and play crucial role in the regulation of ethylene production during ripening. Here, we report a comparative ripening pattern in five different naturally occurring banana cultivars namely Cavendish (AAA), Rasthali (AAB), Kanthali (AB), Poovan (AAB) and Monthan (ABB), which have distinct genome composition. We found a distinct variation in the climacteric ethylene production and in-vivo ACC oxidase activity level during the ripening stages in the five cultivars. We identified the cDNAs for MA-ACS1 and MA-ACO1 from the five cultivars and studied the transcript accumulation patterns of the two genes, which correlated well with the differential timing in the expression of these two genes during ripening. The GCC-box is one of the ethylene-responsive elements (EREs) found in the promoters of many ethylene-inducible genes. We have identified a GCC-box motif (putative ERE) in the promoters of MA-ACS1 and MA-ACO1 in banana cultivars. DNA-protein interaction studies revealed the presence of a GCC-box-specific DNA-binding activity in the fruit nuclear extract and such DNA-binding activity was enhanced following ethylene treatment. South-Western blotting revealed a 25-kDa nuclear protein that binds specifically to GCC-box DNA in the climacteric banana fruit. Together, these results indicate the probable involvement of the GCC-box motif as the cis-acting ERE in the regulation of MA-ACS1 and MA-ACO1 during ripening in banana fruits via binding of specific ERE-binding protein.

Analysis of processivity of mungbean dideoxynucleotide-sensitive DNA polymerase and detection of the activity and expression of the enzyme in the meristematic and meiotic tissues and following DNA damaging agent

Analysis of the processivity of mungbean ddNTP-sensitive DNA polymerase showed the incorporation of approximately 35-40 nucleotides per binding event in the replication assays involving M13 ss DNA template with 5'-labeled 17-mer primer. Optimal processivity was obtained with 100-150 mM KCl and 6-8 mM Mg2+ at pH 7.5. The enzyme showed preference for Mg2+ over Mn2+ as the metal activator for processivity. 2', 3' dideoxythymidine 5' triphosphate (ddTTP) and rat DNA pol beta antibody strongly influenced distributive synthesis. Considerable enhancement in processivity was noticed at 1mM ATP and 2-4 mM spermidine while higher concentrations of spermidine caused distributive synthesis. The enzyme was found to be active in both meristematic and meiotic tissues and distinctly induced by EMS treatment. DNA-binding assays revealed distinct binding ability of the enzyme to template/primer and damaged DNA substrate. Together these observations illustrate the probable involvement of the enzyme in replication and repair machinery in higher plants.

Trans-acting factor designated OSBZ8 interacts with both typical abscisic acid responsive elements as well as abscisic acid responsive element-like sequences in the vegetative tissues of indica rice cultivars

Specific cis-acting elements, identified in the stress-regulated promoters, can respond to the changes in the levels of abscisic acid. Most of our previous works were done with ACGT-containing typical abscisic acid responsive elements (ABREs) but not with non-ACGT, GC-rich sequences also present in such promoters. The current communication shows a comparative analysis performed on the binding of rice nuclear proteins, together with the purified transcription factor OSBZ8, to the cis-elements in the promoters of Rab16A (Motif I/Motif II), Osem (Motif A-1/Motif B) and Em (4X ABRE/2X ABRC). Our data show that the extent of binding of nuclear protein from salt-tolerant rice to both typical ABREs and non-ACGT, ABRE-like sequences such as Motif IIa, is much higher than that from salt-sensitive rice and occurs constitutively, i.e., even with the protein from unstressed plants. The complex formation is low and inducible only by salt in the salt-sensitive variety. While Motif I bind to a single 38 kDa protein, Motif IIa bind to two polypeptides of 38 and 29 kDa. We also show here that the activation and binding of OSBZ8 to the upstream regions of salt-inducible genes depends on its phosphorylated state. The novelty of our work is that it shows rice OSBZ8 as the prime factor interacting with both typical ABRE(s) and ABRE-like sequences. To our knowledge, this is also the first report for the detection and identification of Motif IIa (non-ACGT, coupling element-like)-binding factor(s) from rice and their expression pattern in different rice cultivars.

Tobacco proliferating cell nuclear antigen binds directly and stimulates both activity and processivity of ddNTP-sensitive mungbean DNA polymerase

PCNA is well known as a component of DNA replication system and plays important roles in multiple cellular pathways in addition to replication and repair. In this work we have demonstrated the physical and functional interaction between tobacco PCNA and mungbean ddNTP-sensitive DNA polymerase which shares many physicochemical properties with family X-DNA polymerases except with the moderately processive mode of nucleotide incorporation. We have shown here that recombinant PCNA binds directly to mungbean DNA polymerase as revealed in affinity chromatography, pull-down and co-immunoprecipitation approaches. In vitro DNA polymerase activity assay and processivity analyses indicated recombinant PCNA specifically stimulates both activity and processivity of mungbean DNA polymerase. These observations lead to interesting speculation about the functional significance of the ddNTP-sensitive enzyme in replication event in higher plants since the enzyme has been shown to be active and expressed at an elevated level during the endoreduplication stages in developing mungbean seeds.

Transgenic tobacco plants overexpressing the heterologous lea gene Rab16A from rice during high salt and water deficit display enhanced tolerance to salinity stress

The full length Rab16A, from the indica rice Pokkali, was introduced into tobacco by Agrobacterium-mediated transformation. The transgene was stably integrated into the genome and they originated from different lines of integration. Expression of Rab16A transcript driven by its own promoter (stress inducible) in T2 progenies, only when triggered by salinity/ABA/PEG (Polyethylene glycol)-mediated dehydration, but not at the constitutive level, led to the stress-induced accumulation of RAB16A protein in the leaves of transgenic plants. The selected independent transgenic lines showed normal growth, morphology and seed production as the WT plants without any yield penalty under stress conditions. They exhibited significantly increased tolerance to salinity, sustained growth rates under stress conditions; with concomitant increased osmolyte production like reducing sugars, proline and higher polyamines. They also showed delayed development of damage symptoms with better antioxidative machinery and more favorable mineral balance, as reflected by reduced H2O2 levels and lipid peroxidation, lesser chlorophyll loss as well as lesser accumulation of Na+ and greater accumulation of K+ in 200 mM NaCl. These findings establish the potential role of Rab16A gene in conferring salt tolerance without affecting growth and yield, as well as pointing to the fact that the upstream region of Rab16A behaves as an efficient stress-inducible promoter. Our result also suggests the considerable potential of Group 2 lea genes as molecular tools for genetic engineering of plants towards stress tolerance.

A dideoxynucleotide-sensitive DNA polymerase activity characterized from endoreduplicating cells of mungbean (Vigna radiata L.) during ontogeny of cotyledons

Within this work we describe the purification and biochemical characterization of a ddNTP-sensitive DNA polymerase purified from mungbean (Vigna radiata cv B1, L.) seeds at 18 days after fertilization, when > 70% of the nuclei are reported to be in the endoreduplicated state. The purified enzyme is a single polypeptide of 62 kDa and many of its physicochemical properties are similar to those of mammalian DNA polymerase beta. Similar to the other X-family DNA polymerases, it lacks 3'-5' exonuclease activity and has short gap-filling and strand-displacement activity. The enzyme shows moderately processive DNA synthesis on a single-strand template. The determined N-terminal heptapeptide sequence of the enzyme showed clear homology with helix 1 of the N-terminal single strand DNA-binding domain (residues 32-41) of rat and human DNA polymerase beta. These results represent the first evidence for the identification and characterization of a ddNTP-sensitive DNA polymerase expressed during the endoreduplication cycle that shares biochemical and immunological similarity with mammalian DNA polymerase beta.

An ABRE-binding factor, OSBZ8, is highly expressed in salt tolerant cultivars than in salt sensitive cultivars of indica rice

BACKGROUND

The bZIP class Abscisic acid Responsive Element (ABRE)-binding factor, OSBZ8 (38.5 kD) has been considered to regulate ABA-mediated transcription in the suspension cultured cells of japonica rice. Still, nothing is known about the expression of OSBZ8 at protein level in vegetative tissue of salt sensitive and salt tolerant rice plants. In our previous study, Electrophoretic Mobility Shift Assay (EMSA) of [32P]ABRE-DNA and nuclear extracts prepared from the lamina of Pokkali rice plants has detected the presence of an ABRE-binding factor. Northern analysis has also detected salinity stress induced accumulation of transcripts for bZIP class of factor. Therefore, OSBZ8 was considered to play an important role in the regulation of transcription in the vegetative tissue of rice. The aim of this study is to find out whether OSBZ8 has any role in regulating the NaCl-stress induced gene expression in vegetative tissue and whether the expression of OSBZ8 factor directly correlates with the stress tolerance of different varieties of indica type rice.

RESULTS

Northern analysis of total RNA from roots and lamina of salt-sensitive M-I-48 and salt-tolerant Nonabokra, when probed with the N-terminal unique region of OSBZ8 (OSBZ8p, without the highly conserved basic region), a transcript of 1.3 kb hybridized and its level was much higher in tolerant cultivar. EMSA with Em1a, the strongest ABA Responsive Element till reported from the upstream of EmBP1, and the nuclear extracts from laminar tissue of untreated and salt-treated seedlings of three salt sensitive, one moderately sensitive and two salt tolerant indica rice cultivars showed specific binding of nuclear factor to ABRE element. Intensity of binding was low and inducible in salt sensitive rice cultivars while high and constitutive in salt tolerant cultivars. EMSA with 300 bp 5'upstream region of Rab16A gene, a well known salt stress and ABA-inducible gene of rice, showed formation of two complexes, again very weak in salt sensitive and strong in salt tolerant rice cultivar.

CONCLUSION

The bZIP factor OSBZ8 was found to be present in the ABRE-DNA: protein complex as shown by the supershift of the complex by the purified antiserum raised against OSBZ8p. Treatment of the seedlings with NaCl was found to enhance the complex formation, suggesting the regulation of OSBZ8 gene at both transcriptional and post-translational steps. Comparative EMSA with different varieties of rice suggests a positive correlation with the expression pattern of OSBZ8 and salt tolerance in rice cultivars.

Dideoxynucleoside triphosphate-sensitive DNA polymerase from rice is involved in base excision repair and immunologically similar to mammalian DNA pol beta

A single polypeptide with ddNTP-sensitive DNA polymerase activity was purified to near homogeneity from the shoot tips of rice seedlings and analysis of the preparations by SDS-PAGE followed by silver staining showed a polypeptide of 67 kDa size. The DNA polymerase activity was found to be inhibitory by ddNTP in both in vitro DNA polymerase activity assay and activity gel analysis. Aphidicolin, an inhibitor of other types of DNA polymerases, had no effect on plant enzyme. The 67 kDa rice DNA polymerase was found to be recognized by the polyclonal antibody (purified IgG) made against rat DNA polymerase beta (pol beta) both in solution and also on Western blot. The recognition was found to be very specific as the activity of Klenow enzyme was unaffected by the antibody. The ability of rice nuclear extract to correct G:U mismatch of oligo-duplex was observed when oligo-duplex with 32P-labeled lower strand containing U (at 22nd position) was used as substrate. Differential appearance of bands at 21-mer, 22-mer, and 51-mer position in presence of dCTP was visible only with G:U mismatch oligo-duplex, but not with G:C oligo-duplex. While ddCTP or polyclonal antibody against rat-DNA pol beta inhibits base excision repair (BER), aphidicolin had no effect. These results for the first time clearly demonstrate the ability of rice nuclear extract to run BER and the involvement of ddNTP-sensitive pol beta type DNA polymerase. Immunological similarity of the ddNTP-sensitive DNA polymerase beta of rice and rat and its involvement in BER revealed the conservation of structure and function of ddNTP-sensitive DNA pol beta in plant and animal.

Clinicoimmunologic studies on Phoenix sylvestris Roxb. pollen: an aeroallergen from Calcutta, India

BACKGROUND

This study highlights the allergenicity and allergenic components of the pollen of Phoenix sylvestris Roxb. (PS), or date sugar palm, which is predominantly airborne in the air of Greater Calcutta.

METHODS

A 2-year aerobiologic survey was performed by Burkard sampler. PS pollen extract was used in skin tests of allergic patients, fractionated by (NH4)2SO4 and the Sephacryl S-200 column. The allergenicity of each fraction was checked by skin test and IgE ELISA inhibition. The principal allergenic fraction, Fr.lla, was separated in 11% SDS-PAGE, and its allergenicity was confirmed by IgE ELISA inhibition and immunoblotting.

RESULTS

PS pollen grains were found to be prevalent in the air of the suburban zone of Calcutta from January to March with a peak in February. The pollen extract showed high (44.07%) positive skin reaction on 540 respiratory allergic patients. Among the (NH4)2SO4 cut fractions, Fr.II was the most active one, and it was resolved into four subfractions in the Sephacryl S-200 column. Fr.lla was the principal allergenic fraction, showing the presence of two components of 33 and 66 kDa in SDS-PAGE. In IgE immunoblotting, both of the components were found to be allergenic.

CONCLUSIONS

The PS pollen grain is an important aeroallergen from Calcutta, India. The 33- and 66-kDa components are the major allergens present in the relevant pollen extract.

Expression of arginine decarboxylase in seedlings of indica rice (Oryza sativa L.) cultivars as affected by salinity stress

The effect of salinity stress on the activity of arginine decarboxylase (ADC, EC 4.1.1.19), the first enzyme in biosynthesis of polyamines (PA) from arginine, as well as its transcript level has been compared in salt-sensitive (M-1-48) and salt-tolerant (Pokkali) rice cultivars. Treatment of 72 h grown seedlings either with increasing concentrations of NaCl or with 150 mM NaCl for different time periods, showed a gradual increase of activity in Pokkali. In M-1-48 an immediate increase followed by sharp decrease was observed on prolonged treatment beyond 6 h or above 150 mM NaCl. To generate a DNA probe for ADC, the polymerase chain reaction was used with oat genomic DNA and sequence-specific primers. A region of oat genomic DNA containing a coding sequence for 166 amino acids of the C-terminal part of the ADC enzyme was amplified and called OAD1. Southern analysis of EcoRI- or BamHI-cut genomic DNAs from different cultivars of rice with OAD1 as the probe revealed strong hybridization with one DNA fragment of rice and restriction fragment length polymorphism (RFLP) was noticed. Northern analysis of total RNA of rice with OAD1 as the probe revealed hybridization with a transcript of similar size to the ADC transcript in oat. While in Pokkali, at least a 20-fold accumulation of OAD1 homologous transcript was detected after treatment with 200 mM NaCl, only a seven-fold increase in transcript level was found in M-1-48 after 150 mM NaCl treatment. Results suggest that in the salt-tolerant rice cultivar Pokkali, ADC enzyme activity increases and its transcript also accumulates during the prolonged salinity stress, this mechanism is absent in the salt-sensitive rice cultivar M-1-48 where a prolonged period of salinity stress down-regulates both ADC activity and its transcript level.

A mammalian 2-5A system functions as an antiviral pathway in transgenic plants

Resistance to virus infections in higher vertebrates is mediated in part through catalysis of RNA decay by the, interferon-regulated 2-5A system. A functional 2-5A system requires two enzymes, a 2-5A synthetase that produces 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A) in response to double-stranded RNA, and the 2-5A-dependent RNase L. We have coexpressed these human enzymes in transgenic tobacco plants by using a single plasmid containing the cDNAs for both human RNase L and a low molecular weight form of human 2-5A synthetase under control of different, constitutive promoters. Expression of the human cDNAs in the transgenic plants was demonstrated from Northern blots, by specific enzyme assays, and by immunodetection (for RNase L). Infection of leaves, detached or in planta, of the coexpressing transgenic plants by tobacco mosaic virus, alfalfa [correction of alfafa] mosaic virus, or tobacco etch virus resulted in necrotic lesions. In contrast, leaves expressing 2-5A synthetase or RNase L alone and leaves containing the plasmid vector alone produced typical systemic infections. While alfalfa mosaic virus produced lesions only in the inoculated leaves regardless of the concentration of virus in the inoculum, high, but not low, levels of tobacco etch virus inoculum resulted in escape of virus to uninoculated leaves. Nevertheless, there was a substantial reduction of tobacco etch virus yield as measured by ELISA assay in the coexpressing transgenic plants. These results indicate that expression of a mammalian 2-5A system in plants provides resistance to virus infections.

Characteristics and contributions of defective, ecotropic, and mink cell focus-inducing viruses involved in a retrovirus-induced immunodeficiency syndrome of mice

LP-BM5 murine leukemia virus, a derivative of Duplan-Laterjet virus, contains a mixture of replication-competent B-tropic ecotropic and mink cell focus-inducing (MCF) viruses and a defective genome that is the proximal cause of a syndrome, murine AIDS (MAIDS), characterized by lymphoproliferation and immunodeficiency. The defective (BM5d) and ecotropic components of this mixture were molecularly cloned, and complete (BM5d) or partial (ecotropic) nucleotide sequences were determined. BM5d closely resembled the Du5H genome cloned from the Duplan virus, featuring a highly divergent p12 sequence in the gag open reading frame. In MAIDS-sensitive C57BL/6 mice, BM5d was detected in tissues within 2 weeks of infection but was absent from tissues of the MAIDS-resistant strain, A/J, 12 weeks after infection. B-cell-lineage tumors from mice with MAIDS contained and expressed BM5d, and clonal integrations of this genome were variably associated with clonal expansions of B cells in infected mice. Finally, mRNA crosshybridizing with a probe for BM5d was present in spleen but not kidney cells of uninfected B6 mice.

Cell-cycle-specific and serum-dependent expression of gamma-actin mRNA in Swiss mouse 3T3 cells

We isolated cDNA clones that represent genes whose expression is enhanced when resting Swiss mouse 3T3 cells are stimulated to proliferate with serum. Two clones (designated pME1 and pMR6) were analyzed further. A partial sequence analysis of the pME1 insert DNA indicated that it contained a 104-base-pair stretch with extensive homology to the 3' untranslated region of gamma actin. Similar analysis of the insert DNA from the pMR6 clone indicated that it did not correspond to any previously reported gene sequence. We used the pME1 clone as a probe to determine the level of gamma actin-specific transcript in 3T3 cells under a variety of conditions. The level of gamma actin-specific mRNA began to increase in resting cells upon serum stimulation and reached a peak at 6 h. Thereafter its level declined, and by 24 h it was hardly detectable. In contrast, pMR6-specific transcript was detectable in resting cells but remained elevated even at 24 h poststimulation. The level of gamma-actin mRNA was elevated in resting cells by 12-O-tetradecanoylphorbol-13-acetate, calcium ionophore A23187, and bombesin and to a lesser extent by cholera toxin, fibroblast-derived growth factor, and dibutyryl cyclic AMP. However, insulin, vasopressin, or epidermal growth factor failed to enhance gamma-actin mRNA levels in resting cells. Inhibitors of transcription diminished the induction of gamma-actin mRNA. Gamma-actin gene was superinduced in serum-stimulated cells by cycloheximide, an inhibitor of translation. Analysis of proteins from serum-stimulated cells by two-dimensional gel electrophoresis indicated that enhanced transcription of gamma-actin mRNA resulted in a concomitant increase in the corresponding actin protein. The possible role of gamma actin, a component of the cytoskeleton, in the regulation of cell growth is discussed.

Serology of tuberculosis. III. Crossed immunoelectrophoretic analysis of sera from tuberculosis and leprosy patients with antigens from BCG

Sera from tuberculous and leprous patients have been examined for antibody reactivities against components of BCG sonicate (BCGS) antigen. A crossed immunoelectrophoresis with intermediate gel reference system was used in which more than 40 components of BCGS could be identified. Forty (74.1%) out of 54 tuberculous sera and 68 (90.7%) out of 75 leprous sera reacted with at least 1 component of BCGS. While tuberculous sera reacted with 9 distinct components of BCGS, leprous sera reacted with at least 12. Components of BCGS precipitated by tuberculous sera were not specific as they were also precipitated by leprous sera. Overall, non-specific antibody responses were found to be dominant among tuberculous sera and by comparison, the reactivity of leprous sera with BCGS components was of a higher magnitude. Among tuberculous sera, precipitating activity was maximal among those taken from chronic treated cases with relapse followed by those obtained from treated and untreated new cases. Some components of BCGS to which both tuberculous and leprous sera showed strong reactivity have been characterized. It is concluded that immunoprecipitation methods with BCG derived antigens are not useful for the detection of a specific antibody response in tuberculosis or for discrimination between tuberculosis and leprosy.

Serology of tuberculosis. II. Measurement of antibodies to Mycobacterium tuberculosis by a passive haemagglutination test in human tuberculosis

A simple and sensitive passive haemagglutination (PHA) test has been evaluated in the serology of human tuberculosis. Double aldehyde stabilized red cells were sensitized with cell extracts and PPD antigens from M. tuberculosis (H37Rv) and used as reagents in the test. The study was conducted on sera from 71 bacteriologically confirmed cases of tuberculosis and their controls, inclusive of 59 healthy blood donors and 28 non-tuberculous chest disease patients. In addition, 318 random samples of sera and 107 finger prick blood samples collected on filter papers from apparently healthy people were examined. For comparative evaluation, tuberculous patients' sera were examined by enzyme linked immunosorbent assay (ELISA) and crossed immunoelectrophoresis (CIE). The distribution of IgG and IgM type antimycobacterial antibodies (AMA) in tuberculous patients' sera was evaluated by a modified PHA test. The results of the study indicated that the PHA test was a sensitive method for the quantitation of antibodies, which could be demonstrated in all groups of sera studied. The PHA test and ELISA with the antigens used were not found to be specific enough for the serodiagnosis of tuberculosis; the results indicated the need to investigate several immunological approaches for this purpose. Both tests did differentiate between the mean AMA levels of tuberculous patients and their controls and both showed treated and relapsed cases of tuberculosis to contain higher serum levels of antibodies than did new cases. Both tests were found to be more sensitive than CIE with the intermediate gel technique. The PHA test was found to be sensitive enough for the measurement of antibodies in finger-prick blood samples, indicating its potential for field studies.

Serology of tuberculosis. I. Standardization of passive haemagglutination test for the measurement of antibodies to Mycobacterium tuberculosis

A passive haemagglutination (PHA) test has been described for the measurement of antibodies to M. tuberculosis (H37Rv). Red cells stabilized successively with pyruvic aldehyde and glutaraldehyde were sensitized with soluble antigens from M. tuberculosis and used as reagents in the PHA test. In mice and rabbits immunized with M. tuberculosis antigens, the PHA test could reliably measure antibody response, following both primary and secondary immune stimuli. The sensitized red cells used for the PHA test were found to retain their haemagglutinating potency for 8 weeks and 4 months when stored appropriately at +4 degrees C and -20 degrees C, respectively. The test was found to be satisfactory in terms of sensitivity, simplicity and reproducibility.

Isolation of dermatophytes from rural and urban soil samples in premises of infected and non-infected animals

Animal houses wherein animals infected with ringworm were detected were considered as premises of infected and infection free houses were considered as premises of the non-infected. Fifty soil samples from each of the premises in each of rural and urban areas were examined for the presence of dermatophytes. The premises of the infected showed higher Isolation Rate of dermatophytes. Of the four species of dermatophytes isolated, T. mentagrophytes (granular) was present in the soil of the infected premises only, while T. terrestre, M. nanum and M. gypseum were present in both the premises in both the rural and urban areas.

Hydatid disease in Pondicherry

An analysis of hospital and laboratory records for the period of 1971-1979 revealed 45 confirmed cases of hydatid disease. The majority were young adult (21-30 years) labourers. The commonest site of lesion was lower lobe of the left lung with the liver occupying second place. A few uncommon sites of involvement were also observed. Casoni's test was positive in 48% of cases. Eosinophilia was a usual associated finding. This report shows Pondicherry to be endemic for hydatid disease.

Serology of leprosy. II. Demonstration of specific antibodies to mycobacterium leprae by counter current electrophoresis

A rapid and simple method for the demonstration of specific antibodies to Mycobacterium leprae using counter current electrophoresis (CCE) has been described. Three types of antigens (sonicate antigen, surface antigen and purified protoplasmic protein antigen) were prepared from purified M. leprae and tested against sera from patients with different types of leprosy, and their healthy household contacts, by CCE. Antibodies specific to M. leprae were demonstrated by CCE after absorption of sera with M tuberculosis and M. vaccae. All advanced forms of leprosy (LL and BL) and a lesser number of other forms of leprosy (BB, BT and TT) showed specific antibodies reactive with the three types of soluble antigens from M. leprae and antibodies reactive with soluble antigens from M. tuberculosis and M. vaccae. The latter type of antibodies were however removed by prior absorption of sera with respective mycobacteria. The applicability of the simple electrophoresis method in the serology of leprosy is discussed.

Serology of leprosy. I. Indirect hemagglutination test with stabilized sensitized red cells

An indirect hemagglutination (IHA) test has been described for the qualitative and quantitative detection of antibodies specific to Mycobacterium leprae. Aldehyde stabilized red cells were sensitized with a sonicate antigen prepared from M. leprae purified from armadillo liver. These cells were titrated against sera from patients with different types of leprosy, their healthy household contacts and patients with tuberculosis. Specific antibodies were demonstrated in leprous sera by IHA test after absorption of sera with M. tuberculosis and M. vaccae. All advanced forms of leprosy (LL and BL) and a variable number of other forms of leprosy (BB, BT and TT) showed a positive result with an IHA titre of 1 in 32 or above. None of the household contact sera nor sera from tuberculosis patients showed a positive IHA test. The application of the simple hemagglutination test in the immunoepidemiology of leprosy is discussed.