Induction of systemic immunity through nasal-associated lymphoid tissue (NALT) of mice intranasally immunized with Brucella abortus malate dehydrogenase-loaded chitosan nanoparticles

Infection with Brucella abortus causes contagious zoonosis, brucellosis, and leads to abortion in animals and chronic illness in humans. Chitosan nanoparticles (CNs), biocompatible and nontoxic polymers, acts as a mucosal adjuvant. In our previous study, B. abortus malate dehydrogenase (Mdh) was loaded in CNs, and it induced high production of pro-inflammatory cytokines in THP-1 cells and systemic IgA in BALB/C mice. In this study, the time-series gene expression analysis of nasal-associated lymphoid tissue (NALT) was performed to identify the mechanism by which Mdh affect the target site of nasal immunization. We showed that intranasal immunization of CNs-Mdh reduced cell viability of epithelial cells and muscle cells at first 1 h, then induced cellular movement of immune cells such as granulocytes, neutrophils and lymphocytes at 6h, and activated IL-6 signaling pathway at 12h within NALT. These activation of immune cells also promoted signaling pathway for high-mobility group box 1 protein (HMGB1), followed by the maturation of DCs required for mucosal immunity. The CNs also triggered the response to other organism and inflammatory response, showing it is immune-enhancing adjuvant. The ELISA showed that significant production of specific IgA was detected in the fecal excretions and genital secretions from the CNs-Mdh-immunized group after 2 weeks-post immunization. Collectively, these results suggest that B. abortus Mdh-loaded CNs triggers activation of HMGB1, IL-6 and DCs maturation signaling within NALT and induce production of systemic IgG and IgA.

Effects of In Ovo Administration of DHEA on Lipid Metabolism and Hepatic Lipogenetic Genes Expression in Broiler Chickens During Embryonic Development

In order to study the mechanism of DHEA (Dehydroepiandrosterone) in reducing fat in broiler chickens during embryonic development, fertilized eggs were administrated with DHEA before incubation and its effect on lipid metabolism and expression of hepatic lipogenetic genes was investigated. The mRNA levels of acetyl CoA carboxylase (ACC), fatty acid synthase (FAS), malic enzyme (ME), apolipoprotein B100 (apoB100) and sterol regulator element binding protein-1c (SREBP-1c) were determined using real time quantitative PCR. Samples of livers were collected from the chickens on days 9, 14, and 19 of embryonic development as well as at hatching. Blood samples were extracted on days 14, 19 of incubation and at hatching. The results showed that DHEA decreased the concentration of triacyglycerol in the blood and the content in liver, and the mRNA levels of ACC, FAS, ME, SREBP-1c and apoB. This suggested that DHEA decreased the expression of hepatic lipogenetic genes and suppressed triglycerols transport, by which it reduced the deposition of fat in adipose tissue in broiler chickens during embryonic development and hatching.

Endosulfan effects on muscle malate dehydrogenase of the freshwater catfish Clarias batrachus

The effects of a sublethal concentration of an organochlorine pesticide endosulfan were investigated on crude and purified forms of cytoplasmic malate dehydrogenase (cMDH) and mitochondrial malate dehydrogenase (mMDH) in the muscle of the freshwater catfish Clarias batrachus. Endosulfan treatment reduced significantly the activity and the specific activity of cMDH and mMDH but had no effect on total cytoplasmic and mitochondrial protein contents. This indicates a decline in the efficiency of aerobic energy metabolism in endosulfan-treated fish. The polyacrylamide gel electrophoresis showed two distinct isoforms (C1 and C2) of cMDH and only one form of mMDH. The inhibition produced by endosulfan in vivo was of mixed noncompetitive/uncompetitive type for crude as well as purified cMDH and mMDH. However, in vitro inhibition was of simple noncompetitive and mixed competitive/noncompetitive type for purified cMDH and mMDH, respectively. Citrate was found to be an uncompetitive inhibitor of cMDH and mixed noncompetitive/uncompetitve inhibitor of mMDH. The inhibitory patterns were modulated by endosulfan. These results demonstrate inhibitory effects of endosulfan on skeletal muscle MDH of the freshwater catfish Clarias batrachus and inhibition effects are mediated through enzyme/substrate/endosulfan complexing.

Bound substrate polypeptides can generally stabilize the tetradecameric structure of Cpn60 and induce its reassembly from monomers

We demonstrate that the previously observed stabilizing effect by the enzyme rhodanese of the oligomeric structure of Cpn60 is general and can be provided by six other proteins that can interact with Cpn60. All these substrate proteins, which include examples that are monomeric, as well as oligomeric polypeptides in their native states, were shown previously to be assisted in their refolding by the chaperonin. Strikingly, during the disassembly of Cpn60 in the presence of any of the substrate proteins, significant amounts of intermediates were detected. Furthermore, unfolded substrate proteins induce the reassembly of tetradecameric Cpn60 from monomers, and binding of each substrate protein stabilizes Cpn60 quaternary structure.

Apparent inhibition of ATP citrate lyase by L-glutamate in vitro is due to the presence of glutamine synthetase

Preincubation in assay mixture for 30 min at 37 degrees C of ATP citrate lyase from rat brain and liver results in 65-70% inhibition in the presence of 10 mM L-glutamate. This inhibition is specific since none of the known brain metabolites of glutamate shows this effect. ATP and ammonium sulphate-suspended, commercially purified malate dehydrogenase are both important in the generation of inhibition; citrate and NADH are not. The ATP citrate lyase activity in desalted crude extracts and 11% polyethylene glycol-precipitated fractions is inhibited but the enzyme purified by dye affinity chromatography is unaffected. Such purification reveals the presence of a factor responsible for the generation of the inhibition shown to be of Mr 380,000. These lines of evidence implicate endogenous glutamine synthetase, and the involvement of this enzyme is established by the use of its inhibitor L-methionine sulphoximine and by the addition of purified glutamine synthetase to restore the glutamate inhibition of purified ATP citrate lyase. The phenomenon probably arises from the production by glutamine synthetase of ADP, a known product inhibitor of ATP citrate lyase. Therefore contrary to previous reports elsewhere, L-glutamate has no role in the regulation of brain ATP citrate lyase and thus the supply of cytoplasmic acetyl groups for biosynthesis.