一株产纤维素酶细菌的筛选、鉴定及产酶条件优化

目的：筛选1株产纤维素酶的细菌。方法：通过对从腐烂朽木及其附近土壤中得到的样品进行富集培养、分离纯化得到16株纤维素分解菌,经刚果红染色鉴定和液体发酵培养后对其进行了菌种初步鉴定及产酶条件的初步优化。结果：获得1株纤维素酶分泌量较高的细菌LT3。结论：LT3为革兰氏阳性菌,菌体成杆状,经发酵优化培养后,较适产酶条件为甘蔗渣20g/L,pH7.0、30℃培养120h,CMC酶活为71.17U/mL,滤纸酶活为33.37U/mL。通过克隆其16S rDNA序列,对其进行系统进化分析,鉴定为蜡状芽孢杆菌。     

Fluorescent microsphere method is suitable for chronic bone blood flow measurement: a long-term study after meniscectomy in rabbits.

The fluorescent microsphere (FM) method is considered a reliable technique to determine regional bone blood flow (RBBF) in acute experiments. In this study, we verified the accuracy and validity of this technique for measurement of RBBF in a long-term experiment and examined RBBF after meniscectomy. Twenty-four anesthetized female New Zealand white rabbits (3 groups, each n = 8) received consecutive left ventricular injections of FM in defined time intervals after meniscectomy: group 1 from preoperation to 3 wk postoperation; group 2 from 3 to 7 wk postoperation; and group 3 from 7 to 11 wk postoperation. To test the precision of the FM method, two FM species were injected simultaneously at the first and last measurement. After the experiment, humeri, femora, tibiae, and reference organs (kidney, lung, brain) were removed and dissected according to standardized protocols. Fluorescence was determined in each reference blood and tissue sample, and blood flow values were calculated. Blood flow in kidney, lung, and brain revealed no significant difference between right and left side and remained unchanged during the observation period, thus excluding errors due to shunting and dislodging of spheres in our experiments. Comparison of relative bone blood flow values obtained by simultaneously injected FM showed an excellent correlation at the first and last injection, indicating valid RBBF measurements in long-term experiments. We found a significant increase in RBBF 3 wk after meniscectomy in the right tibial condyles compared with the nonoperated left side. Similar changes were found in the femoral condyles. RBBF in other regions of tibia, femur, and humerus revealed no significant differences between right- and left-sided bone samples of the same region. Our results demonstrate that the FM method is valid for measuring RBBF in long-term experiments. In addition, we were able to demonstrate that meniscectomy leads to an increase in RBBF in the tibial condyles at a very early stage. This increase might be caused by stress-induced alterations of the subchondral bone.     

Kabuki syndrome and trisomy 10p

Kabuki syndrome (KS) (MIM 147920) is a multiple congenital anomalies/mental retardation syndrome of unknown cause. There is multisystem involvement of anomalies, including 1) unique facial features, 2) postnatal growth retardation, 3) mild-to-moderate mental retardation, 4) skeletal anomalies and 5) dermatoglyphic abnormalities. Kabuki syndrome remains a clinical diagnosis despite significant research on detection of the genetic cause. We present 10 patients with Kabuki syndrome with a brief overview of the syndrome. An additional male patient and his affected aunt, both with trisomy 10p due to unbalanced segregation of a familial translocation, are also discussed for overlapping features and differential clinical diagnosis of the two conditions. Considering a significant overlap in clinical pictures of Kabuki syndrome and trisomy 10p in these two patients, as well as the previous patients with chromosomal abnormalities, we conclude that chromosome analysis is an important step in clinical work-up of patients with Kabuki syndrome.     

Anatomy of the bony pelvis of a relatively large-bodied strepsirrhine primate from the late middle Eocene Pondaung Formation (central Myanmar)

Recent survey of the fossiliferous variegated mudstones of the PK1 locality (Sabapondaung) in the late middle Eocene Pondaung Formation (central Myanmar) has led to the recovery of a partial right innominate of a relatively large-bodied primate. Given its size and provenance, this bone probably belongs to the same individual represented by the NMMP 20 primate partial skeleton described previously from the same locality. The new fossil, which preserves the region around the acetabulum and the adjacent part of the ilium, clearly exhibits strepsirrhine rather than anthropoid affinities. This addition to our knowledge of the NMMP 20 partial skeleton allows us to reassess the different locomotor interpretations that have been proposed for this specimen. Aspects of pelvic morphology suggest that the NMMP 20 partial skeleton documents a primate that probably engaged in active arboreal quadrupedalism similar to that practiced by medium-sized Malagasy lemurids rather than lorislike slow moving and climbing. Given the conflicting phylogenetic signals provided by NMMP 39 (a talus showing anthropoid affinities) and NMMP 20 (a partial skeleton bearing adapiform affinities), it appears that two higher-level taxonomic groups of relatively large-bodied primates are documented in the Pondaung Formation. The recent discovery of two taxa of sivaladapid adapiforms from the Pondaung Formation indicates that the assumption that the NMMP 20 partial skeleton belongs to an amphipithecid can no longer be sustained. Instead, this specimen apparently documents a third large-bodied sivaladapid species in the Pondaung Formation.     

The upper dentition and face of Pondaungia cotteri from central Myanmar

A specimen of Pondaungia from the late middle Eocene Pondaung Formation in central Myanmar includes maxillary fragments and parts of the dentition, some hitherto undocumented, including the upper central incisor, canine, premolars and molars. Pondaungia has a large spatulate I1 closely resembling that of crown anthropoids. It possesses a stout projecting upper canine (like anthropoids) but differs from that tooth of crown anthropoids in lacking a strong mesial groove. There are three upper premolars of which P2 is distinctly smaller than P3 or P4. P3 has a buccolingually oriented mesial profile and an inflated distal profile resembling that of parapithecids and crown anthropoids. The distolingual molar cusp is a hypocone and is not homologus with the "pseudohypocone" of notharctines because the cusp is neither twinned with the protocone nor attached to a Nannopithex-fold. Pondaungia has a stout zygomatic root with a strongly demarcated muscle scar for the superficial masseter situated well above the occlusal plane. The inferior orbital margin is not preserved but the inflated suborbital region allows for the inference that the orbit was small. This specimen is not sufficiently well preserved to identify if there was postorbital closure. However, a specimen of the frontal bone of Amphipithecus shows that its orbital septum was absent or poorly developed. If, as commonly supposed, Pondaungia andAmphipithecus are sister taxa, postorbital closure was probably absent in Pondaungia. The large incisors, molars with poorly developed crests and thick enamel, together with the stoutly developed and strong dorsal component of the force vector of the superficial masseter muscle suggest that Pondaungia had a diet low in fiber, but that included hard food objects like nuts or seeds. The present material adds to the structural similarities between Pondaungia and anthropoids, but whether these similarities are due to shared descent or functional and adaptive convergence remains unresolved.     

Circadian variation of nitric oxide synthase activity in mouse tissue

Endogenous nitric oxide (NO) is an important mediator in the processes that control biological clocks and circadian rhythms. The present study was designed to elucidate if NO synthase (NOS) activity in the brain, kidney, testis, aorta, and lungs and plasma NO_x levels in mice are controlled by an endogenous circadian pacemaker. Male BALB/c mice were exposed to two different lighting regimens of either light-dark 14:10 (LD) or continuous lighting (LL). At nine different equidistant time points (commencing at 09:00h) blood samples and tissues were taken from mice. The plasma and tissue homogenates were used to measure the levels of NO₂+ NO₃^- (NO_x) and total protein. The NO_x concentrations were determined by a commercial nitric oxide synthase assay kit, and protein content was assessed in each homogenate tissue sample by the Lowry method. Nitric oxide synthase activity was calculated as pmol/mg protein/h. The resulting patterns were analyzed by the single cosinor method for pre-adjusted periods and by curve-fitting programs to elucidate compound rhythmicity. The NOS activity in kidneys of mice exposed to LD exhibited a circadian rhythm, but no rhythmicity was detected in mice exposed to LL. Aortic NOS activity displayed 24h rhythmicity only in LL. Brain, testis, and lung NOS activity and plasma NO_x levels displayed 24h rhythms both in LD and LL. Acrophase values of NOS activity in brain, kidney, testis, and lungs were at midnight corresponding to their behavioral activities. Compound rhythms were also detected in many of the examined patterns. The findings suggest that NOS activity in mouse brain, aorta, lung, and testis are regulated by an endogenous clock, while in kidney the rhythm in NOS activity is synchronized by the exogenous signals.     

Degradation of a Caulobacter soluble cytoplasmic chemoreceptor is ClpX dependent

In order to determine whether ClpXP-mediated proteolysis is a common mechanism used to regulate the chemotaxis machinery during the cell cycle of Caulobacter crescentus, we have characterized a soluble cytoplasmic chemoreceptor, McpB. The mcpB gene lies adjacent to the major chemotaxis operon, which encodes 12 chemotaxis proteins, including the membrane chemoreceptor McpA. Like McpA, McpB possesses a C-terminal CheBR docking motif and three potential methylation sites, which we suggest are methylated. The McpB protein is degraded via a ClpX-dependent pathway during the swarmer-to-stalked cell transition, and a motif, which is 3 amino acids N-terminal to the McpB CheBR docking site, is required for proteolysis. Analysis of the degradation signal in McpB and McpA reveals a common motif present in the other four chemoreceptors that possess CheBR docking sites. A green fluorescent protein (GFP) fusion bearing 58 amino acids from the C terminus of McpA, which contains this motif, is degraded, suggesting that the C-terminal sequence is sufficient to confer ClpXP protease susceptibility.     

Peroxynitrite produces relaxations on the rat anococcygeus muscle

Effects of peroxynitrite (ONOO-), its stable product 3-nitrotyrosine (NT) and sodium nitroprusside (SNP) on isolated rat anococcygeus muscle were investigated. Administration of 0.1-1.0 mM ONOO- or 0.01-100.0 microM SNP produced concentration-dependent relaxations on the phenylephrine (2 microM)-precontracted muscle. Time courses of these relaxations to ONOO- and SNP were not similar and decomposed ONOO- caused a biphasic response composed of an initial contraction followed by a relaxation. NT (0.01-0.1 mM) either incubated for 20 min prior to precontraction or given during precontraction plateau did not attenuate precontraction or ONOO(-)-induced relaxations. Results of the present study demonstrate that ONOO- relaxes rat anococcygeus muscle specifically while its stable metabolite NT has no effect.     

Relationship between Marteilioides chungmuensis infection and reproduction in the Pacific oyster, Crassostrea gigas

Marteilioides chungmuensis, a protozoan paramyxean parasite, infects the oocytes of the Pacific oyster, Crassostrea gigas. The effects of infection on the reproductive cycle of C. gigas were investigated over two consecutive years at Okayama Prefecture, Japan. In male oysters, gonadal development began during February/March, maturity was achieved in June and spawning activity extended from July to September. In November and December, male oysters were not seen, probably because their gonads regressed to connective tissue and they transformed into undifferentiated oysters. By contrast, female oysters, in which parasite spore formation occurred, were still carrying oocytes until the following March and the spawning process of female oysters took 5 months longer than that of males in epizootic areas. The prevalence of M. chungmuensis infection increased from July to September, when most female oysters had their spawning period, and declined from October to the following April when oysters were at the spent stage. The prevalence of infection increased again in May of the following year and high prevalence was observed in the following July. When prevalence was compared between oysters of different age classes, higher prevalence was detected in older than in younger oysters. Histological examination showed that infected oysters produced oocytes continuously and spawned repeatedly from October to March, during which period healthy oysters were reproductively inactive. Parasites can infect the oocytes of infected oysters throughout the longer spawning period. These observations suggest that M. chungmuensis extends the reproductive period of infected oysters for its own reproductive benefit.