Diel change in inorganic nitrogenous nutrient dynamics and associated oxygen stoichiometry along the Pearl River Estuary.

The reactive nitrogen (N) emitted from continents significantly perturbs the pristine N cycle around the land-ocean boundary resulting in eutrophication and hypoxia. As nutrients are transported downstream through an estuary, various types of biological processes co-occur to modulate nitrogen speciation to influence the biogeochemical habitats for downstream microorganisms. We surveyed the Pearl River Estuary to examine the N transfer dynamics among nitrogen species with considering process-specific oxygen production and consumption. By using 15N pulse-tracing techniques, we measured ammonia oxidation and uptakes of ammonium, nitrite, and nitrate simultaneously under dark and light conditions in parallel. Light strongly inhibited nitrification but enhanced N uptake, and such light effect was further considered in the calculation for nitrogen transformation rates over a diel cycle. We found both oxidation and uptake of ammonium decreased seaward as substrate decreased. The nitrifier and phytoplankton work in antiphase to draw down incoming ammonium rapidly. Contrary to ammonium uptake, uptake of nitrite and nitrate showed a seaward increasing pattern. Such an inverse spatial pattern implies a shift in N preference for phytoplankton. Such high ammonium preference inhibits nitrate/nitrite uptake allowing them to behave conservatively in the estuary and to travel farther to outer estuary. By integrating oxygen consumption and production induced by N transformation processes over the diel cycle, oxygen was produced although allochthonous ammonium input is high (∼250 µM). For most stations, ammonium was completely consumed within 2 days, some stations even less than 0.5 days, implying that although the water residence time is short (2-15 days), tremendous input of ammonium N from upstream was transformed into particulate organic or nitrate forms during traveling to modulate the biogeochemical niche, including substrate, organics and oxygen, of coastal microbes in water column and sediments.

Substrate regulation leads to differential responses of microbial ammonia-oxidizing communities to ocean warming.

In the context of continuously increasing anthropogenic nitrogen inputs, knowledge of how ammonia oxidation (AO) in the ocean responds to warming is crucial to predicting future changes in marine nitrogen biogeochemistry. Here, we show divergent thermal response patterns for marine AO across a wide onshore/offshore trophic gradient. We find ammonia oxidizer community and ambient substrate co-regulate optimum temperatures (Topt), generating distinct thermal response patterns with Topt varying from ≤14 °C to ≥34 °C. Substrate addition elevates Topt when ambient substrate is unsaturated. The thermal sensitivity of kinetic parameters allows us to predict responses of both AO rate and Topt at varying substrate and temperature below the critical temperature. A warming ocean promotes nearshore AO, while suppressing offshore AO. Our findings reconcile field inconsistencies of temperature effects on AO, suggesting that predictive biogeochemical models need to include such differential warming mechanisms on this key nitrogen cycle process.

Petroclostridium xylanilyticum gen. nov., sp. nov., a xylan-degrading bacterium isolated from an oilfield, and reclassification of clostridial cluster III members into four novel genera in a new Hungateiclostridiaceae fam. nov.

A rod-shaped, Gram-stain-positive, obligately anaerobic, xylan-degrading bacterium, SK-Y3T, was isolated from oily-sludge of Shengli oilfield, China. Optimum growth occurred at 50 °C, at pH 7.5 and without addition of NaCl. The predominant cellular fatty acids of strain SK-Y3T were iso-C15 : 0, anteiso-C15 : 0 and iso-C17 : 0, and the main polar lipids were glycolipids (GL), lipids (L), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG); no respiratory quinones were detected. The genomic DNA G+C content was 37.2 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain SK-Y3T belongs to clostridial cluster III, exhibiting 91-92% sequence similarity to the most closely related species, namely Clostridium clariflavum, Clostridium straminisolvens and Acetivibrio cellulolyticus. Based on distinct physiological and phylogenetic differences from the aforementioned described taxa, strain SK-Y3T (=DSM 103557T=ACCC 19952T) is proposed as the type strain of a novel species of a new genus, Petroclostridium xylanilyticum gen. nov., sp. nov. Furthermore, analysis through 16S rRNA gene, ribosomal protein and whole genome sequences indicated that clostridial cluster III members should be reclassified into four novel genera for which the names Hungateiclostridium gen. nov., Thermoclostridium gen. nov., Ruminiclostridium gen. nov. and Pseudoclostridium gen. nov. are proposed. In combination with the genera Anaerobacterium, Cellulosibacter, Ercella, Fastidiosipila, Mageeibacillus, Pseudobacteroides, Petroclostridium and Saccharofermentans, clostridial cluster III members formed a monophyletic clade within the order Clostridiales but that was clearly distinguished from other Ruminococcaceae members, which is proposed as a novel family, Hungateiclostridiaceae fam. nov.

Volasertib suppresses tumor growth and potentiates the activity of cisplatin in cervical cancer.

Volasertib (BI 6727), a highly selective and potent inhibitor of PLK1, has shown broad antitumor activities in the preclinical and clinical studies for the treatment of several types of cancers. However, the anticancer effect of volasertib on cervical cancer cells is still unknown. In the present study, we show that volasertib can markedly induce cell growth inhibition, cell cycle arrest at G2/M phase and apoptosis with the decreased protein expressions of PLK1 substrates survivin and wee1 in human cervical cancer cells. Furthermore, volasertib also enhances the intracellular reactive oxidative species (ROS) levels, and pretreated with ROS scavenger N-acety-L-cysteine totally blocks ROS generation but partly reverses volasertib-induced apoptosis. In addition, volasertib significantly potentiates the activity of cisplatin to inhibit the growth of cervical cancer in vitro and in vivo. In brief, volasertib suppresses tumor growth and potentiates the activity of cisplatin in cervical cancer, suggesting the combination of volasertib and cisplatin may be a promising strategy for the treatment of patients with cervical cancer.

Spastin mutation screening in Chinese patients with pure hereditary spastic paraplegia.

BACKGROUND: Hereditary spastic paraplegia (HSP) is a clinically and genetically heterogeneous group of neurodegenerative diseases. Mutations in the spastin (SPAST) gene are the most common cause of pure HSP. However, few data are available regarding the clinical and genetic spectrum of HSP among Chinese patients. METHODS: Clinical data were collected at diagnosis and follow-up of 42 Chinese patients with pure HSP. All seventeen exons of the SPAST gene were directly sequenced. Additionally, we used a multiplex ligation dependent probe amplification (MLPA) assay targeting the SPAST gene to evaluate large exon deletion or insertion mutations in patients without SPAST point mutations. RESULTS: The age of disease onset of our patients was 19.6 ± 14.4 years. Six novel variations were found, including three missense mutations (p. L363P, p. D441V, and p. S595R), one insertion (c.1511dupT (p. Y505Ifs*7)), and two larger deletions (exons 5-17 and exons 10-17). Four previously reported mutations, including p. S399L, c.1215_c.1219delTATAA (p. N405Kfs*36), exon 1 deletion, and exon 16 deletion, were detected. The SPAST mutation rate was 40% (4/10) in Chinese familial patients and 33.33% (7/21) in Chinese sporadic pure HSP patients. The frequency of large deletions was high in both AD-HSP (20%, 2/10) and sporadic HSP (14.28%, 3/21). CONCLUSION: SPAST mutations are common in Chinese patients with pure HSP. Large exon deletions are an important cause of AD-HSP and sporadic pure HSP in Chinese patients. Large fragment tests should be performed to explore large SPAST mutations in familial and sporadic HSP patients without SPAST point mutations.

SQSTM1 mutations in Han Chinese populations with sporadic amyotrophic lateral sclerosis.

Mutations in the sequestosome 1 gene (SQSTM1) have recently been identified in patients with amyotrophic lateral sclerosis, accounting for 1.11%-4.92% of familial ALS and 2.42%-4.37% of sporadic amyotrophic lateral sclerosis (SALS). The mutation spectrum of SQSTM1 in Chinese patients with SALS remains unknown. Three hundred and six patients with SALS from the Department of Neurology, West China Hospital of Sichuan University were recruited for this study. From the same region, 350 healthy individuals were recruited as a control group. The encoding regions of SQSTM1 were screened by direct sequencing. Three novel nonsynonymous mutations- p. I99L, p. D337E, and p. L341V-were identified in 3 patients with SALS, none of which were found in healthy controls. The male patient carrying mutation p. I99L presented limb symptom at age of 34 and died in 34 months. Two late-onset patients carrying D337E and p. L341V mutations had bulbar and limb onset, respectively. Moreover, a c.1166-14_1166-11delTACT mutation in the intron 7 was found in a living male patient with limb onset at age of 62. None of the patients carrying SQSTM1 mutation showed clinical evidence of concomitant Paget disease of bone or mutation of the valosin-containing protein gene. The mutation frequency of SQSTM1 was 0.98% in Chinese patients with SALS, which was lower than those in other racial populations.

PFN1 mutations are rare in Han Chinese populations with amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with unknown pathophysiological mechanisms. Profilin 1 gene (PFN1) has been identified as a causative gene, which accounts for 1% to 2% of familial ALS. In this study, we investigated the mutation spectrum of PFN1 in Chinese patients with ALS. A total of 550 ALS patients (including 540 sporadic ALS [SALS] and 10 familial ALS) from the Department of Neurology, West China Hospital of Sichuan University, were recruited for the study. From the same region, 545 healthy control individuals (HC) were recruited as a control group. The encoding regions of the PFN1 gene were screened by direct sequencing. Novel candidate mutations or variations were confirmed by polymerase chain reaction-restriction fragment length polymorphism. A novel nonsynonymous p.R136W mutation was identified in an early-onset SALS female patient. A novel synonymous mutation p.L88L detected in a late-onset SALS female patient was considered nonpathogenic, as it was also detected in a control subject. No mutations were found in 10 familial ALS patients. Moreover, we found a significant difference in the genotype distribution of reported rs13204 (p.L112L) between SALS patients and HC (p = 0.0030). The frequency of minor allele 'T' of rs13204 in the SALS group was significantly lower than that in HC (p = 0.0040, OR = 0.7270, 95% CI = 0.5848-0.9039). Our results suggest that PFN1 mutation is an uncommon cause of ALS in the Han Chinese population. The SNP rs13204 of the PFN1 gene may have an important function in ALS development. The phenotype of ALS patients with mutantPFN1 gene varies among different genetic backgrounds.