ClpB is an essential stress regulator of Mycobacterium tuberculosis and endows survival advantage to dormant bacilli

The ability to tolerate multiple host derived stresses, resist eradication and persist within the infected individuals is central to the pathogenicity of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB). Mycobacterial survival is contingent upon sensing environmental perturbations and initiating a fitting response to counter them. Therefore, understanding of molecular mechanisms underlying stress tolerance and sensing in Mtb is critical for devising strategies for TB control. Our study aims to delineate the role of ClpB, a heat shock protein of Hsp100 family, in the general stress response and persistence mechanisms of Mtb. We demonstrate that Mtb requires ClpB to survive under stressful conditions. Additionally, we show that ClpB is necessary for the bacteria to persist in latency-like conditions such as prolonged hypoxia and nutrient-starvation. The disruption of ClpB results in aberrant cellular morphology, impaired biofilm formation and reduced infectivity of Mtb ex vivo. Our study also reports an alternative role of ClpB as a chaperokine which elicits inflammatory response in host. We conclude that ClpB is essential for Mtb to survive within macrophages, and plays a crucial part in the maintenance of dormant Mtb bacilli in latent state. The absence of ClpB in human genome makes it an attractive choice as drug target for TB.

Expression of Kisspeptin and its receptor in the hypothalamus of cyclic and acyclic buffalo (Bubalus bubalis)

Kisspeptin (Kiss1), neurokinin-B (NKB) and dynorphin (Dyn) neurons regulate the surge and pulsatile centres of gonadotropin releasing hormone (GnRH) in the hypothalamus and are modulated by the ovarian steroids. Accordingly, we studied the temporospatial expression of Kiss1, its receptor and other genes that regulate GnRH in the preoptic area (POA) and arcuate (ARC) regions of hypothalamus at different phases of bubaline estrous cycle. Brain of buffalo (n = 32) was collected immediately after exsanguination and categorized into early luteal (EL), mid luteal (ML), follicular (FL) stages and acyclic (n = 8/group). Total RNA was extracted from the POA and ARC of each stage and real time PCR amplification of Kiss1, Kiss1r, NKB, NKB receptor (NKBR), Dyn, Dyn receptor (OPRK1), GnRH1, ERα, PR, LEPR and GHSR was done using GAPDH as endogenous control and acyclic stage as calibrator group. Further, immunolocalization of Kiss1 and Kiss1r was done on the hypothalamus. In the POA, significant up-regulation of Kiss1 and NKB with a concomitant down-regulation of Dyn transcripts was recorded at FL stage. There was, however, down-regulation of Kiss1 and Kiss1r during the EL perhaps due to the loss of estradiol as a consequence of ovulation. On the other hand, in the ARC, there was a significant up-regulation of Kiss1 and Dyn at FL and ML, while NKB transcript was consistently down-regulated at any stage of estrous cycle. In the POA, expression of ERα was not modulated; however, PR was down-regulated in the EL. In the ARC, the ERα expression was significantly up-regulated in the EL, whereas, PR was moderately expressed irrespective of the stage of estrous cycle. The immunolocalization study revealed the presence of Kiss1 and Kiss1r in the POA and ARC in the cyclic buffalo with relative abundance at FL. The transcriptional profile of the genes suggests that there is estrous cycle stage specific expression of Kiss1, Kiss1r and other GnRH regulating genes in the POA and ARC regions of hypothalamus in the buffalo. Up-regulation of Kiss1r in the POA during ML and ARC during EL indicates the involvement of kisspeptinergic system in the regulation of low LH pulse frequencies during the early and mid luteal phases in the cyclic buffalo.

Long-term impact of conservation agriculture and diversified maize rotations on carbon pools and stocks, mineral nitrogen fractions and nitrous oxide fluxes in inceptisol of India

Given the increasing scarcity of production resources such as water, energy and labour coupled with growing climatic risks, maize-based production systems could be potential alternatives to intensive rice-wheat (RW) rotation in western Indo-Gangetic Plains (IGP). Conservation agriculture (CA) in maize systems has been widely promoted for minimizing soil degradation and ensuring sustainability under emerging climate change scenario. Such practices are also believed to provide mitigation co-benefits through reduced GHG emission and increased soil carbon sequestration. However, the combined effects of diversified crop rotations and CA-based management on GHG mitigation potential and other co-benefits are generally over looked and hence warrant greater attention. A field trial was conducted for 5-years to assess the changes in soil organic carbon fractions, mineral-N, N₂O emission and global warming potential (GWP) of maize-based production systems under different tillage & crop establishment methods. Four diversified cropping systems i.e. maize-wheat-mungbean (MWMb), maize-chickpea-Sesbania (MCS), maize-mustard-mungbean (MMuMb) and maize-maize-Sesbania (MMS) were factorially combined with three tillage & crop establishment methods i.e. zero tilled permanent beds (PB), zero-tillage flat (ZT) and conventional tillage (CT) in a split-plot design. After 5-years of continued experimentation, we recorded that across the soil depths, SOC content, its pools and mineral-N fractions were greatly affected by tillage & crop establishment methods and cropping systems. ZT and PB increased SOC stock (0-30 cm depth) by 7.22-7.23 Mg C ha^-1 whereas CT system increased it only by 0.88 Mg C ha^-1as compared to initial value. Several researchers reported that SOC & mineral-N fraction contents in the top 30 cm soil depth are correlated with N₂O-N emission. In our study, global warming potential (GWP) under CT system was higher by 18.1 and 17.4%, compared to CA-based ZT and PB, respectively. Among various maize systems, GWP of MMS were higher by 11.2, 6.7 and 6.6%, compared that of MWMb (1212 kg CO₂-eq. ha^-1), MCS (1274 kg CO₂-eq. ha^-1) and MMuMb (1275 kg CO₂-eq. ha^-1), respectively. The results of our study suggest that CA and diversified crop rotations should be promoted in north-western IGP and other similar agro-ecologies across the globe for ensuring food security, restoration of soil health and climate change mitigation, the key sustainable development goals (SDGs).

Serine/Threonine Protein Phosphatase PstP of Mycobacterium tuberculosis Is Necessary for Accurate Cell Division and Survival of Pathogen

Protein phosphatases play vital roles in phosphorylation-mediated cellular signaling. Although there are 11 serine/threonine protein kinases in Mycobacterium tuberculosis, only one serine/threonine phosphatase, PstP, has been identified. Although PstP has been biochemically characterized and multiple in vitro substrates have been identified, its physiological role has not yet been elucidated. In this study, we have investigated the impact of PstP on cell growth and survival of the pathogen in the host. Overexpression of PstP led to elongated cells and partially compromised survival. We find that depletion of PstP is detrimental to cell survival, eventually leading to cell death. PstP depletion results in elongated multiseptate cells, suggesting a role for PstP in regulating cell division events. Complementation experiments performed with PstP deletion mutants revealed marginally compromised survival, suggesting that all of the domains, including the extracellular domain, are necessary for complete rescue. On the other hand, the catalytic activity of PstP is absolutely essential for the in vitro growth. Mice infection experiments establish a definitive role for PstP in pathogen survival within the host. Depletion of PstP from established infections causes pathogen clearance, indicating that the continued presence of PstP is necessary for pathogen survival. Taken together, our data suggest an important role for PstP in establishing and maintaining infection, possibly via the modulation of cell division events.

Recent Developments in Anti-dotes Against Anthrax

The etiologic agent of disease anthrax, Bacillus anthracis, causes recurrent outbreaks among the livestock and intermittent infections in humans across the world. Controlling animal infections by vaccination can minimize the incidence of disease in humans. Prevention of anthrax in occupationally exposed personnel is achieved through vaccination with either live spores or precipitates of culture supernatants from attenuated strains of B. anthracis. However, anthrax vaccination of the large human population is impractical as well as inappropriate. Broad-range antibiotics like amoxicillin, ciprofloxacin, clindamycin, streptomycin, and penicillin G are recommended for the treatment of human anthrax infections, but the threat of antibiotic resistant strains always remains. Moreover, in the absence of any specific symptom (s) during early infection, the diagnosis of anthrax is delayed causing elevated levels of anthrax toxin component which could be fatal. For these reasons, there is a need to develop new antimicrobial agents against virulent B. anthracis to effectively combat this fatal pathogen. Over the last two decades, extensive studies have been carried out to develop specific inhibitors against virulence factors of B. anthracis such as capsule, protective antigen, lethal factor and edema factor. Research has also been focused in developing inhibitors of anthrax toxin receptors (including the use of receptor decoys) and host furin endoproteases which are required for activation of toxin. This review highlights the recent progress made in developing the diverse countermeasures for anthrax infections targeting B. anthracis virulence factors and their counterparts in host.

clpC operon regulates cell architecture and sporulation in Bacillus anthracis

The clpC operon is known to regulate several processes such as genetic competence, protein degradation and stress survival in bacteria. Here, we describe the role of clpC operon in Bacillus anthracis. We generated knockout strains of the clpC operon genes to investigate the impact of CtsR, McsA, McsB and ClpC deletion on essential processes of B. anthracis. We observed that growth, cell division, sporulation and germination were severely affected in mcsB and clpC deleted strains, while none of deletions affected toxin secretion. Growth defect in these strains was pronounced at elevated temperature. The growth pattern gets restored on complementation of mcsB and clpC in respective mutants. Electron microscopic examination revealed that mcsB and clpC deletion also causes defect in septum formation leading to cell elongation. These vegetative cell deformities were accompanied by inability of mutant strains to generate morphologically intact spores. Higher levels of polyhydroxybutyrate granules accumulation were also observed in these deletion strains, indicating a defect in sporulation process. Our results demonstrate, for the first time, the vital role played by McsB and ClpC in physiology of B. anthracis and open up further interest on this operon, which might be of importance to success of B. anthracis as pathogen.

Lithium-induced sinus node dysfunction at therapeutic serum levels

Lithium-induced cardiotoxicity, though rare at therapeutic levels, has been reported frequently in overdoses. We report a patient who developed sinus bradycardia while being treated with lithium carbonate even though the serum lithium levels were within the therapeutic range. It reversed following withdrawal of lithium and did not reappear with subsequent treatment with valproate.

Bioconversion of lignocellulosic fraction of water-hyacinth (Eichhornia crassipes) hemicellulose acid hydrolysate to ethanol by Pichia stipitis

Fermentation of acid hydrolysate of water-hyacinth (Eichhornia crassipes), a free floating aquatic plant has been investigated for ethanol production. The dilute acid treatment has been applied to utilize the maximum hemicellulosic content of the water-hyacinth. The goal of this work was to investigate, both experimentally and theoretically using mathematical tools, a fermentative system utilizing water-hyacinth (Eichhornia crassipes) hemicellulose acid hydrolysate as a substrate for ethanol production using Pichia stipitis. It was found that 72.83% of xylose was converted to ethanol with a yield of 0.425 g(p)/g(s) and productivity of 0.176 g(p)/L/h. An appropriate mathematical model was developed to explain theoretically the bioconversion of this hemicellulose acid hydrolysate to ethanol and the model was tested statistically to check the validity of the model.

Alopecia areata and affected skin CRH receptor upregulation induced by acute emotional stress

BACKGROUND

Recent evidence indicates that acute stress can precipitate a number of dermatological conditions, including alopecia areata. This effect may be mediated by corticotropin-releasing hormone (CRH) released locally in the skin from dorsal root ganglia or immune cells. CRH typically acts through activation of specific receptors that are either type 1 or types 2 alpha and 2 beta. CRH, or related peptides such as urocortin, could have proinflammatory effects directly or through activation of mast cells leading to destruction of the hair root.

OBJECTIVES

To investigate the expression of CRH receptors on the affected skin of patients who developed alopecia areata following acute emotional stress.

METHODS

Scalp skin biopsies were obtained from 1 normal volunteer and 3 patients after ring infiltration of the relevant site with lidocaine. The biopsies were frozen and were later processed for in situ hybridization for CRH receptors type 1 or types 2 alpha and 2 beta. Sections showing positive results were photographed.

RESULTS

The skin from the normal volunteer showed weak background expression of all three receptor types. However, skin from the affected sites of all 3 patients studied showed intense expression only on the type 2 beta receptor around the hair follicles.

CONCLUSION

Acute emotional stress may precipitate alopecia areata by activation of overexpressed type 2 beta CRH receptors around the hair follicles leading to intense local inflammation.

Acute immobilization stress triggers skin mast cell degranulation via corticotropin releasing hormone, neurotensin, and substance P: A link to neurogenic skin disorders

Many skin disorders, such as atopic dermatitis and psoriasis, worsen during stress and are associated with increased numbers and activation of mast cells which release vasoactive, nociceptive, and proinflammatory mediators. Nontraumatic acute psychological stress by immobilization has been shown to induce mast cell degranulation in the rat dura and colon. Moreover, intradermal injection of corticotropin-releasing hormone (CRH) or its analogue urocortin (10(-5)-10(-7) M) induced skin mast cell degranulation and increased vascular permeability. Here, we investigated the effect of acute immobilization stress on skin mast cell degranulation by light microscopy and electron microscopy. Immobilization for 30 min resulted (P < 0.05) in degranulation of 40.7 +/- 9.1% of skin mast cells compared to 22.2 +/- 7.3% in controls killed by CO(2) or 17.8 +/- 2.4% in controls killed by pentobarbital. Pretreatment intraperitoneally (ip) with antiserum to CRH for 60 min prior to stress reduced (P < 0.05) skin mast cell degranulation to 21.0 +/- 3. 3%. Pretreatment with the neurotensin (NT) receptor antagonist SR48692 reduced (P < 0.05) mast cell degranulation to 12.5 +/- 3.4%, which was significantly (P < 0.05) below control levels. In animals treated neonatally with capsaicin to deplete their sensory neurons of their neuropeptides, such as substance P (SP), mast cell degranulation due to immobilization stress was reduced to about 15%. This is the first time that stress has been shown to trigger skin mast cell degranulation, an action not only dependent on CRH, but apparently also involving NT and SP. These findings may have implications for the pathophysiology and possible therapy of neuroinflammatory skin disorders such as atopic dermatitis, neurogenic pruritus, or psoriasis, which are induced or exacerbated by stress.

Potent mast cell degranulation and vascular permeability triggered by urocortin through activation of corticotropin-releasing hormone receptors

Urocortin (Ucn) is related to corticotropin-releasing hormone (CRH), and both are released in the brain under stress where they stimulate CRH 1 and 2 receptors (CRHR). Outside the brain, they may have proinflammatory actions through activation of mast cells, which are located perivascularly close to nerve endings and degranulate in response to acute psychological stress. Here, we report that a concentration of intradermal Ucn as low as 10 nM induced dose-dependent rat skin mast cell degranulation and increased vascular permeability. This effect appeared to be equipotent to that of calcitonin gene-related peptide and neurotensin. Ucn-induced skin vasodilation was inhibited by pretreatment with the mast cell stabilizer disodium cromoglycate (cromolyn) and was absent in the mast cell-deficient W/Wv mice. The selective nonpeptide CRH receptor 1 antagonist, antalarmin and the nonselective peptide antagonist astressin both reduced vascular permeability triggered by Ucn but not that by Substance P or histamine. In contrast, the peptide antagonist alpha-helical CRH-(9-41) reduced the effect of all three. The vasodilatory effect of Ucn was largely inhibited by pretreatment with H1 receptor antagonists, suggesting that histamine is the major mediator involved in vitro. Neuropeptide depletion of sensory neurons, treatment with the ganglionic blocker hexamethonium, or in situ skin infiltration with the local anesthetic lidocaine did not affect Ucn-induced vascular permeability, indicating that its in situ effect was not mediated through the peripheral nervous system. These results indicate that Ucn is one of the most potent triggers of rat mast cell degranulation and skin vascular permeability. This effect of Ucn may explain stress-induced disorders, such as atopic dermatitis or psoriasis, and may lead to new forms of treatment.

Corticotropin-releasing hormone induces skin mast cell degranulation and increased vascular permeability, a possible explanation for its proinflammatory effects

Mast cells are involved in atopic disorders, often exacerbated by stress, and are located perivascularly close to sympathetic and sensory nerve endings. Mast cells are activated by electrical nerve stimulation and millimolar concentrations of neuropeptides, such as substance P (SP). Moreover, acute psychological stress induces CRH-dependent mast cell degranulation. Intradermal administration of rat/human CRH (0.1-10 microM) in the rat induced mast cell degranulation and increased capillary permeability in a dose-dependent fashion. The effect of CRH on Evans blue extravasation was stronger than equimolar concentrations of the mast cell secretagogue compound 48/80 or SP. The free acid analog of CRH, which does not interact with its receptors (CRHR), had no biological activity. Moreover, systemic administration of antalarmin, a nonpeptide CRHR1 antagonist, prevented vascular permeability only by CRH and not by compound 48/80 or SP. CRHR1 was also identified in cultured leukemic human mast cells using RT-PCR. The stimulatory effect of CRH, like that of compound 48/80 on skin vasodilation, could not be elicited in the mast cell deficient W/Wv mice but was present in their +/+ controls, as well as in C57BL/6J mice; histamine could still induce vasodilation in the W/Wv mice. Treatment of rats neonatally with capsaicin had no effect on either Evans blue extravasation or mast cell degranulation, indicating that the effect of exogenous CRH in the skin was not secondary to or dependent on the release of neuropeptides from sensory nerve endings. The effect of CRH on Evans blue extravasation and mast cell degranulation was inhibited by the mast cell stabilizer disodium cromoglycate (cromolyn), but not by the antisecretory molecule somatostatin. To investigate which vasodilatory molecules might be involved in the increase in vascular permeability, the CRH injection site was pretreated with the H1-receptor antagonist diphenhydramine, which largely inhibited the CRH effect, suggesting that histamine was involved in the CRH-induced vasodilation. The possibility that nitric oxide might also be involved was tested using pretreatment with a nitric oxide synthase inhibitor that, however, increased the effect of CRH. These findings indicate that CRH activates skin mast cells at least via a CRHR1-dependent mechanism leading to vasodilation and increased vascular permeability. The present results have implications for the pathophysiology and possible therapy of skin disorders, such as atopic dermatitis, eczema, psoriasis, and urticaria, which are exacerbated or precipitated by stress.