Biohydrogen generation by mesophilic anaerobic fermentation of microcrystalline cellulose

Sixteen batch experiments were performed to evaluate the stability, kinetics, and metabolic paths of heat-shocked digester (HSD) sludge that transforms microcrystalline cellulose into hydrogen. Highly reproducible kinetic and metabolic data confirmed that HSD sludge could stably convert microcrystalline cellulose to hydrogen and volatile fatty acids (VFA) and induce metabolic shift to produce alcohols. We concluded that clostridia predominated the hydrogen-producing bacteria in the HSD sludge. Throughout this study the hydrogen percentage in the headspace of the digesters was greater than 50% and no methanogenesis was observed. The results emphasize that hydrogen significantly inhibited the hydrogen-producing activity of sludge when initial microcrystalline cellulose concentrations exceeded 25.0 g/L. A further 25 batch experiments performed with full factorial design incorporating multivariate analysis suggested that the ability of the sludge to convert cellulose into hydrogen was influenced mainly by the ratio of initial cellulose concentration (So) to initial sludge density (Xo), but not by interaction between the variables. The hydrogen-producing activity depended highly on interaction of So x (So/Xo). Through response surface analysis it was found that a maximum hydrogen yield of 3.2 mmol/g cellulose occurred at So = 40 g/L and So/Xo = 8 g cellulose/g VSS. A high specific rate of 18 mmol/(g VSS-d) occurred at So = 28 g/L and So/Xo = 9 g cellulose/g VSS. These experimental results suggest that high hydrogen generation from cellulose was accompanied by low So/Xo.     

COMPARISON OF GROWTH AND REPRODUCTION BETWEEN TWO POPULATIONS OF SARGASSUM SILIQUASTRUM IN PING CHAU, HONG KONG

In Ping Chau Island of Hong Kong, two populations of Sargassum siliquastrum are present. One is in the shallow water of about 1 to 3 m Chart Datum (CD), and the other one in deeper water of 5 to 10 m CD. These two populations are separated by an extensive sand patch. Individuals of the "shallow" water population increased their size from a mean length of 8.3 ± 3.6 (SD) cm in Aug 1998 to a maximum of 48.2 ± 29.9 cm in early Jan 1999 before they started to die back. In the following year, they attained a minimum of 6.1 ± 3.8 cm in May 1999 and a maximum of 56.1 ± 23.6 cm in Dec 1999. Their reproductive period lasted for two to three months from Jan to Feb 1999, and again from Nov 1999 to Jan 2000. The "deep" water individuals increased their size to a maximum of 123 ± 50.8 cm at the end of Jan 1999 and started to die back in Feb, 1999. They again reached their maximum mean length in Jan 2000. Their reproductive period lasted for five to six months from Sept 1998 to Feb 1999 and again from Sept 1999 to Jan 2000. The "deep" water individuals tended to be longer in size and they attained their maximum growth a month later than the "shallow" water individuals. Their reproductive season tended to start earlier and lasted longer than those in the "shallow" water. These differences in the phenology of the two populations may be related to the temperature differences (up to 5° C difference in summer) between the two depths. Sargassum siliquastrum is likely to be a cold adapted species such that warmer temperature in the shallow water has compressed and shortened their rapid growth and reproductive period to within the few colder months in fall and winter.     

猫皮层体感Ⅱ区内脏伤害感受神经元的电生理特性及形态特征

应用胞内记录和标记技术,观察了猫皮质第Ⅱ感觉区内脏大神经代表区的神经元对电刺激内脏大神经反应诱发反应及形态特征。结果表明,在２５１个记录单位中,有１０９个为内脏伤害性感受神经元,其诱发反应分为兴奋性、抑制性及混合性三类。在形式上ＩＳＰＳ及ＥＰＳＰ－ＩＰＳＰ序列反应较多。对其中２１个神经元用神经生物素进行细胞内电泳标记,显示细胞的形态特点是胞体较小,分布于皮质Ⅱ、Ⅲ、Ⅴ层,其中兴奋性和神经元形态多为     

ATL3 Is a Tubular ER-Phagy Receptor for GABARAP-Mediated Selective Autophagy

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Pleiotrophin Gene Therapy for Peripheral Ischemia: Evaluation of Full-Length and Truncated Gene Variants

Pleiotrophin (PTN) is a growth factor with both pro-angiogenic and limited pro-tumorigenic activity. We evaluated the potential for PTN to be used for safe angiogenic gene therapy using the full length gene and a truncated gene variant lacking the domain implicated in tumorigenesis. Mouse myoblasts were transduced to express full length or truncated PTN (PTN or T-PTN), along with a LacZ reporter gene, and injected into mouse limb muscle and myocardium. In cultured myoblasts, PTN was expressed and secreted via the Golgi apparatus, but T-PTN was not properly secreted. Nonetheless, no evidence of uncontrolled growth was observed in cells expressing either form of PTN. PTN gene delivery to myocardium, and non-ischemic skeletal muscle, did not result in a detectable change in vascularity or function. In ischemic hindlimb at 14 days post-implantation, intramuscular injection with PTN-expressing myoblasts led to a significant increase in skin perfusion and muscle arteriole density. We conclude that (1) delivery of the full length PTN gene to muscle can be accomplished without tumorigenesis, (2) the truncated PTN gene may be difficult to use in a gene therapy context due to inefficient secretion, (3) PTN gene delivery leads to functional benefit in the mouse acute ischemic hindlimb model.     

A retrospective study of DNA prevalence of porcine parvoviruses in Mexico and its relationship with porcine circovirus associated disease

Worldwide, many emerging porcine parvoviruses (PPVs) have been linked to porcine circovirus-2 (PCV2) associated disease (PCVAD), which includes post-weaning multi-systemic wasting syndrome (PMWS), PCV2-related reproductive failure (PCV2-RF), as well as other syndromes. To determine the DNA prevalence of PPVs and their relationship with PMWS and PCV2-RF in Mexico, 170 formalin-fixed paraffin-embedded tissues were selected from archival collections to detect PPVs using a nested polymerase chain reaction. The tissues were composed of 50 PMWS cases, 20 age-matched tissues from healthy pigs, 56 PCV2-related reproductive failure (PCV2⁺-RF) cases, and 44 PCV2^--RF cases. Overall, PPV2 and PPV6 were the most prevalent species (90.0% and 74.7%, respectively). In 8–11 week old pigs, the highest prevalence was for PPV6 and PPV3. Concerning reproductive failure, the PCV2-affected farms had a significantly higher prevalence for PPV6 (61.6%) and PPV5 (36.4%) than the PCV2-unaffected farms (35.0% and 5.0%, respectively). The concurrent infection rate was high, being significant for PPV2/PPV4 and PPV1/PPV5 within the PMWS cases and for PPV6/PPV5 among the PCV2⁺-RF tissues. PPV5 showed a significant relationship with PMWS, whereas PPV5 and PPV6 were significant for PCVAD. The prevalence and coinfection rate of PPVs in Mexico were markedly higher than that described in other countries, denoting that PPV5 and PPV6 might have a potential role in PCVAD in Mexico. It is concluded that it is likely that the density population of pigs in Mexico is contributing to high PPV inter-species and PCV2 coinfections which might lead to a different pathogenic outcome.     

Nitric oxide regulates ganoderic acid biosynthesis by the S-nitrosylation of aconitase under heat stress in Ganoderma lucidum

Nitric oxide (NO) is an important signalling molecule in stress response of organisms. We previously reported that NO decreases heat stress (HS)-induced ganoderic acid (GA) accumulation in Ganoderma lucidum. To explore the mechanisms by which NO modulates GA biosynthesis under HS, the effect of NO on the reactive oxygen species (ROS) content was examined. The results showed that NO decreased the production of mitochondrial ROS (mitROS) by 60% under HS. Further research revealed that NO reduced the mitROS content by inhibiting aconitase (Acon) activity. The GA content in Acon-silenced (Aconi) strains treated with NO donor did not differ significantly from that in untreated Aconi strains. To study the mechanism by which Acon activity is inhibited, the S-nitrosylation level of Acon was determined. Biotin-switch technology and mass spectrometry analysis were used to show that Acon is S-nitrosylated at the Cys-594 amino acid residue. Substitution of Cys-594 with a Ser, which cannot be S-nitrosylated, abolished the responsiveness of Acon to the NO-induced reduction in its enzymatic activity. These findings demonstrate that NO inhibits Acon activity through S-nitrosylation at Cys-594. In summary, these findings describe mechanism by which NO regulates GA biosynthesis via S-nitrosylation of Acon under HS condition in G. lucidum.