Hasil untuk "Biochemistry"

M. Peach

B. Halliwell

T. Goodwin

J. Bewley, M. Black

J. C. Stoof, J. Kebabian

C. Bédard, R. Knowles

Ammonia oxidizers (family Nitrobacteraceae) and methanotrophs (family Methylococcaceae) oxidize CO and CH4 to CO2 and NH4+ to NO2-. However, the relative contributions of the two groups of organisms to the metabolism of CO, CH4, and NH4+ in various environments are not known. In the ammonia oxidizers, ammonia monooxygenase, the enzyme responsible for the conversion of NH4+ to NH2OH, also catalyzes the oxidation of CH4 to CH3OH. Ammonia monooxygenase also mediates the transformation of CH3OH to CO2 and cell carbon, but the pathway by which this is done is not known. At least one species of ammonia oxidizer, Nitrosococcus oceanus, exhibits a Km for CH4 oxidation similar to that of methanotrophs. However, the highest rate of CH4 oxidation recorded in an ammonia oxidizer is still five times lower than rates in methanotrophs, and ammonia oxidizers are apparently unable to grow on CH4. Methanotrophs oxidize NH4+ to NH2OH via methane monooxygenase and NH4+ to NH2OH via methane monooxygenase and NH2OH to NO2- via an NH2OH oxidase which may resemble the enzyme found in ammonia oxidizers. Maximum rates of NH4+ oxidation are considerably lower than in ammonia oxidizers, and the affinity for NH4+ is generally lower than in ammonia oxidizers. NH4+ does not apparently support growth in methanotrophs. Both ammonia monooxygenase and methane monooxygenase oxidize CO to CO2, but CO cannot support growth in either ammonia oxidizers or methanotrophs. These organisms have affinities for CO which are comparable to those for their growth substrates and often higher than those in carboxydobacteria. The methane monooxygenases of methanotrophs exist in two forms: a soluble form and a particulate form. The soluble form is well characterized and appears unrelated to the particulate. Ammonia monooxygenase and the particulate methane monooxygenase share a number of similarities. Both enzymes contain copper and are membrane bound. They oxidize a variety of inorganic and organic compounds, and their inhibitor profiles are similar. Inhibitors thought to be specific to ammonia oxidizers have been used in environmental studies of nitrification. However, almost all of the numerous compounds found to inhibit ammonia oxidizers also inhibit methanotrophs, and most of the inhibitors act upon the monooxygenases. Many probably exert their effect by chelating copper, which is essential to the proper functioning of some monooxygenases. The lack of inhibitors specific for one or the other of the two groups of bacteria hampers the determination of their relative roles in nature.

B. Rosen

S. Jacquemoud, S. Ustin, J. Verdebout et al.

C. Bustamante, Y. Chemla, N. Forde et al.

U. Das

Kiziltepe Şemistan, Karakurt Emin, Eser Gizem et al.

Ovine pulmonary adenocarcinoma (OPA) is an infectious and neoplastic disease etiologically linked to the Jaagsiekte sheep retrovirus (JSRV), characterised by tumour lesions of the lung. Because of the economic losses it induces, OPA is of great importance for flock health. In this study, oxidative stress markers and adenosine deaminase (ADA) activity were quantified in lung tissue from sheep, both healthy and those naturally afflicted with OPA. Compared to healthy sheep, malondialdehyde (MDA), nitric oxide (NO ), ceruloplasmin (CP) and ADA concentrations/activities were significantly increased (P<0.05 and P<0.001) in fresh lung tissues from JSRV–infected sheep, while reduced glutathione (GSH) levels were significantly decreased (P<0.05). In conclusion, pronounced oxidative stress and increased ADA enzyme activity were detected in the JSRV–infected sheep. These findings suggest that ADA activity could serve as a biomarker for disease diagnosis.

F. Guéraud, M. Atalay, N. Bresgen et al.

J. Perry, D. Shin, E. Getzoff et al.

M. Jetten, L. Niftrik, M. Strous et al.

Xuyuan Ma, Maozheng Shen, JiaYu Hu et al.

Abstract Background Mitochondrial dyshomeostasis plays an important role in neuronal damage after cerebral ischemia-reperfusion, and Miro1 is a core protein that regulates mitochondrial homeostasis. In this study, we aimed to investigate the neuroprotective effects of bone marrow-derived mesenchymal stem cells (BMSCs) via mitochondrial homeostasis in rats after cardiac arrest (CA), and to clarify the role that the protein Miro1 plays in this protective efficacy. Methods The study compared the effects of BMSCs in which Miro1 was overexpressed BMSCs (BMSCs-mirohi), knocked down (BMSCs-mirolo), and unmodified BMSCs on mitochondrial homeostasis in hippocampal neurons to evaluate their neuroprotective effects of these cells in a rat model of global cerebral ischemia-reperfusion injury. Rats underwent CA modeling for 5 min and received cardiopulmonary resuscitation (CPR). Two hours after the restoration of spontaneous circulation, 1 mL of PBS or 1 mL containing 1 × 106 BMSCs (normal, mirohi, or mirolo) were injected via the femoral vein. The neurological function of rats was assessed based on Neurological Disability Score (NDS) values. Brain histopathological examination was conducted to evaluate brain injury by measuring oxidative stress levels and the apoptosis rate of hippocampal neurons. Immunoblotting and transmission electron microscopy were applied to detect the expression of mitophagy-related proteins in hippocampal neurons. Immunofluorescence was used to track the mitochondria in BMSCs and observe mitochondrial transfer. Additionally, the membrane potential level, oxidative stress level, and ATP content of mitochondria in hippocampal neurons were measured to assess the impact of transplanted BMSCs on mitochondrial quality in these hippocampal neurons. Results Immunofluorescence staining revealed the presence of mitochondria from MitoTracker-labeled BMSCs in rat hippocampal neurons post-CPR. Additionally, the fluorescence intensity of TOMM20 was notably increased following the transplantation of BMSCs. Through immunoblotting experiments, we identified that BMSCs amplified the post-CPR protein expression of LC3, p62, PINK1 and parkin in hippocampal neurons. The number of autophagosomes significantly increased in hippocampal neurons following BMSC transplantation, as observed through transmission electron microscopy. Flow cytometry, Hematoxylin and Eosin (HE) staining, and NDS scoring indicated that BMSCs effectively reduced reactive oxygen species accumulation in hippocampal neurons and mitochondria after CPR. Furthermore, they restored mitochondrial membrane potential and ATP levels in the hippocampus while decreasing apoptosis, ultimately contributing to the restoration of neurological function. Additionally, unlike BMSCs-mirolo, BMSCs-mirohi were able to significantly enhance the efficiency of BMSC-mediated mitochondrial transfer and enhance mitophagy. This amplification, in turn, was found to bolster the protective impact of BMSCs on hippocampal neurons during CPR, thereby contributing to the restoration of rat neurological function. Conclusions These analyses revealed that BMSC transplantation has a dual protective effect by facilitating healthy mitochondrial transfer and promoting the autophagic degradation of damaged mitochondria, effectively enhancing hippocampal neuronal mitochondrial function following CA while reducing neuronal apoptosis, restoring neuronal function, and alleviating neuropathological damage. Moreover, Miro1 can enhance the efficiency of mitochondrial transfer and promote BMSC-mediated mitophagy induction, thereby optimizing the therapeutic effect of BMSCs.

E. Werner, N. Blau, B. Thöny

Qasam M. Ghulam, Jens P. Goetze, Nikolaj Eldrup et al.

Introduction: Abdominal aortic aneurysms (AAAs) with intraluminal thrombus (ILT) are suggested to be more prone to rupture than AAAs without. Prior studies indicate that the von Willebrand factor (vWf) plays a role in the formation of ILT since a positive correlation between ILT volume and vWf has been shown. vWf mediates the tethering of platelets at sites of endothelial injury, and the protease ADAMTS-13 cleaves larger forms of vWf, thus counteracting the thrombosis cascade and maintaining haemostatic balance. When investigating the largest quantifiable thrombus in the human body, it was hypothesised that circulating ADAMTS-13 activity may be associated with ILT size in patients with AAA and the aim was to explore this potential relationship using 3D contrast enhanced ultrasound (3D-CEUS) for ILT volume determination. Report: In this retrospective, exploratory study, 60 patients with AAA were evaluated, and the association between ILT volume and thickness and ADAMTS-13 was estimated using 3D-CEUS. ADAMTS-13 activity was measured in plasma samples obtained the same day. No association between ILT volume (r = −0.03, p = 0.84) or ILT thickness (r = 0.02, p = 0.87) and ADAMTS-13 activity was found. Likewise, when subdividing the group into lowest and highest 50% of ADAMTS-13 activity, the half with the lowest ADAMTS-13 activity (mean ILT volume ±standard deviation [SD]: 32 ± 34 mL) did not differ from the half with the highest ADAMTS-13 activity (43 ± 24 mL) when comparing ILT volume (p = 0.172, F = 2.95) and thickness (p = 0.070). Discussion: After evaluating the largest quantifiable intraluminal thrombus in the vasculature, it was concluded that, surprisingly, circulating ADAMTS-13 activity seems unrelated to ILT formation in AAA.

B. Predmore, D. Lefer, G. Gojon

Xiuxiu Liu, Maoying Han, Wendong Weng et al.

Abstract A genetic system, ProTracer, has been recently developed to record cell proliferation in vivo. However, the ProTracer is initiated by an infrequently used recombinase Dre, which limits its broad application for functional studies employing floxed gene alleles. Here we generated Cre-activated functional ProTracer (fProTracer) mice, which enable simultaneous recording of cell proliferation and tissue-specific gene deletion, facilitating broad functional analysis of cell proliferation by any Cre driver.

Christine Njiru, Wenxin Xue, Sander De Rouck et al.

Abstract Background Generalist herbivores such as the two-spotted spider mite Tetranychus urticae thrive on a wide variety of plants and can rapidly adapt to novel hosts. What traits enable polyphagous herbivores to cope with the diversity of secondary metabolites in their variable plant diet is unclear. Genome sequencing of T. urticae revealed the presence of 17 genes that code for secreted proteins with strong homology to “intradiol ring cleavage dioxygenases (DOGs)” from bacteria and fungi, and phylogenetic analyses show that they have been acquired by horizontal gene transfer from fungi. In bacteria and fungi, DOGs have been well characterized and cleave aromatic rings in catecholic compounds between adjacent hydroxyl groups. Such compounds are found in high amounts in solanaceous plants like tomato, where they protect against herbivory. To better understand the role of this gene family in spider mites, we used a multi-disciplinary approach to functionally characterize the various T. urticae DOG genes. Results We confirmed that DOG genes were present in the T. urticae genome and performed a phylogenetic reconstruction using transcriptomic and genomic data to advance our understanding of the evolutionary history of spider mite DOG genes. We found that DOG expression differed between mites from different plant hosts and was induced in response to jasmonic acid defense signaling. In consonance with a presumed role in detoxification, expression was localized in the mite’s gut region. Silencing selected DOGs expression by dsRNA injection reduced the mites’ survival rate on tomato, further supporting a role in mitigating the plant defense response. Recombinant purified DOGs displayed a broad substrate promiscuity, cleaving a surprisingly wide array of aromatic plant metabolites, greatly exceeding the metabolic capacity of previously characterized microbial DOGs. Conclusion Our findings suggest that the laterally acquired spider mite DOGs function as detoxification enzymes in the gut, disarming plant metabolites before they reach toxic levels. We provide experimental evidence to support the hypothesis that this proliferated gene family in T. urticae is causally linked to its ability to feed on an extremely wide range of host plants.