养殖密度对史氏鲟消化率、摄食率和生长的影响

以体重（43.90±1.75）g史氏鲟为研究对象,研究了0.525、1.171和2.138 kg·m^-2 3种养殖密度对史氏鲟幼鱼生长、摄食率和消化率的影响,实验时间为60 d.结果表明,养殖密度对史氏鲟的生长、摄食率和消化率具有显著影响.高养殖密度不利于史氏鲟的生长,低密度组中史氏鲟的特定生长率和日增重显著高于高密度组,食物转化率显著低于高密度组;特定生长率和日增重随养殖密度的降低而显著增高.低密度组、中密度组中史氏鲟的消化率无显著差异,但均显著高于高密度组.中密度组摄食率显著低于高密度组和低密度组,低密度组摄食率介于两者之间;食物转化率和消化率呈显著负相关,特定生长率与消化率呈显著正相关.     

Carbon Dioxide Fixation by Cells of Streptococcus faecalis var. liquefaciens

Fixation of NaH(14)CO(3) by a heavy cell suspension of Streptococcus faecalis var. liquefaciens was studied. Several nutrients, pyridoxal, riboflavine, adenine, uracil, and O(2) stimulated (14)CO(2) incorporation into cells only under conditions that were adequate for synthesis of cell macromolecules. Biotin increased CO(2) incorporation in the absence of extensive synthesis of macromolecules, whereas O(2) inhibited incorporation under these conditions. When (14)CO(2) fixation was occurring during synthesis of macromolecules, 71% of the (14)C was incorporated into cells and 29% occurred extracellularly. Ninety-three per cent of the cellular (14)C was in protein and 5.5% was in nucleic acid. Aspartic acid was the only amino acid in the protein fraction that was radioactive. Eighty-three per cent of the extracellular (14)C was resistant to precipitation by trichloroacetic acid. When (14)CO(2) fixation was occurring in cells that were not carrying on extensive synthesis of macromolecules, 38% of the (14)C was incorporated into cells and 59% occurred in the supernatant fluid. Sixty-nine per cent of the cellular (14)C was in protein, 21% was in low-molecular-weight compounds, and 9% was in nucleic acid. Addition of unlabeled aspartate to the medium inhibited incorporation of (14)CO(2). Based on studies of the rate of (14)CO(2) fixation, the cells fix CO(2) into a pool of intermediates which are either used for synthesis, primarily protein, or are excreted into the medium.     

云南丽江山慈菇遗传多样性的DALP分析

采用DALP (Direct amplification of length polymorphism) 分子标记技术, 对产自云南的药用植物丽江山慈菇Iphigenia indica (L.) Kunth的9个居群进行DNA指纹检测。筛选出5个引物组合, 扩增共产生131条DNA片段, 其中104 条谱带具有遗传多态性, 约占79 39%, 平均每组引物扩增所得多态条带为20 8, 9个居群平均多态百分率为42 21%。9个居群平均观察等位基因数Na为1 4224, 总Na为1 7939; 平均有效等位基因数Ne 为1 3141, 总Ne 为1 4810; 平均遗传多样性指数H为0 1745, 总H为0 2831; 平均Shannon 多样性指数I 为0 2527, 总I为0 4231; 总基因多样性Ht为0 2831, 居群内多样性Hs 为0 1745, 居群间基因分化系数Gst为0 3834, 即丽江山慈菇有61 66%的遗传变异来自居群内, 38 34%来自居群间, 居群间存在较高水平的遗传分化。滇西北居群的遗传多样性明显高于滇中居群的遗传多样性, 这与滇中地区丽江山慈菇野生资源被大规模挖掘有着直接的关系。     

Evaluation of the rate-limiting steps in the pathway of glucose metabolism in kidney cortex of normal, diabetic, cortisone-treated and growth hormone-treated rats

1. The activities of gluconeogenic and glycolytic enzymes and the concentrations of citrate, ammonia, amino acids, glycogen, glucose 6-phosphate, acetyl-CoA, lactate and pyruvate were measured in kidney cortex of normal, diabetic, cortisone-treated and growth hormone-treated rats. 2. In kidney cortex of diabetic, cortisone-treated and growth hormone-treated rats the activities of glucose 6-phosphatase (EC 3.1.3.9), fructose 1,6-diphosphatase (EC 3.1.3.11) and phosphopyruvate carboxylase (EC 4.1.1.32) were increased. 3. The activities of glutamate dehydrogenase (EC 1.4.1.3), alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.10) and pyruvate carboxylase (EC 6.4.1.1) were increased in diabetic and cortisone-treated rats. In growth hormone-treated rats the activity of aspartate aminotransferase was depressed but those of the other three enzymes were unchanged. 4. The activity of hexokinase (EC 2.7.1.1) was not altered in any of these conditions. Phosphofructokinase (EC 2.7.1.11) activity was depressed only in growth hormone-treated rats. Pyruvate kinase (EC 2.7.1.40) activity was depressed in cortisone-treated and growth hormone-treated rats but unchanged in diabetic rats. 5. Amino acids, acetyl-CoA and glucose 6-phosphate contents were increased in rat kidneys in all these three conditions. Ammonia content was increased in diabetic and cortisone-treated rats but was markedly diminished in growth hormone-treated rats. 6. The [lactate]/[pyruvate] ratio was elevated in diabetic and cortisone-treated rats but unchanged in growth hormone-treated rats. Citrate content was increased in the kidney cortex of diabetic and growth hormone-treated rats but was unchanged in cortisone-treated rats. The activity of ATP citrate lyase (EC 4.1.3.8) was depressed in diabetic and growth hormone-treated rats but was increased in cortisone-treated rats. 7. Glycogen content was moderately elevated in growth hormone-treated rats and markedly elevated in diabetic rats, whereas no change in glycogen content was observed in cortisone-treated rats. Glycogen synthetase (EC 2.4.1.11) activity was unchanged in all these three conditions. Phosphorylase (EC 2.4.1.1) activity was not affected in cortisone-treated rats but was depressed in diabetic and growth hormone-treated rats.     

The NMR-derived conformation of neuropeptide AF,an orphan G-protein coupled receptor peptide

The tertiary structure of the pain modulating and anti-opiate neuropeptide, human neuropeptide AF (NPAF) (the sequence is AGEGLNSQFWSLAAPQRF-NH(2)), was determined by (1)H-NMR. The structure of NPAF was determined in two solvent systems, namely 50%/50% trifluoroethanol-d(3)/H(2)O (TFE/H(2)O) and in the cell membrane mimetic micelle, sodium dodecylsulfate-d(25) (SDS). The receptor for NPAF is an orphan G-protein coupled receptor, and the micellar SDS solvent system was used to emulate the cell membrane surface in line with the Cell Membrane Compartments Theory proposed by R. Schwyzer (Biopolymers, 1995, Vol. 37, pp. 5-16). In both solvent systems, NPAF was found to be primarily alpha-helical within the central portion of the molecule, from Asn(6) to Ala(14). The N-terminus was random in both solvent systems. In the SDS solution, the C-terminal tetrapeptide was structured and formed a type I beta-turn, whereas in TFE/H(2)O it was unstructured, showing the importance of the C-terminal tetrapeptide in receptor recognition. NPAF was found to associate with SDS, and was shown to be near the surface of the micelle by spin label studies with 5-doxyl-stearic acid.     

Changes in intestinal and hepatic thyroid hormone deiodination during spontaneous metamorphosis of the sea lamprey, Petromyzon marinus

We measured microsomal low-K(m) outer-ring deiodination (ORD) and inner-ring deiodination (IRD) activities for thyroxine (T(4)) and 3, 5,3'-triiodothyronine (T(3)) in intestine and liver in nonmetamorphosing (undersized) larvae, immediately premetamorphic larvae, animals in stages 1-7 of metamorphosis, and immediately postmetamorphic sea lampreys (Petromyzon marinus). For intestine: T(4)ORD activity was relatively low in nonmetamorphosing larvae, increased in premetamorphic individuals, was highest in stages 1 and 2 and was very low during stages 3-7; T(4)IRD activity was negligible until stage 3 but increased 4.7-fold through stages 3 to 7 such that T(4)IRD activity was 14 times T(4)ORD activity at stage 6; T(3)ORD activity was undetectable; T(3)IRD activity was not measured through stages 3-7 but correlated with T(4)IRD activity at other stages. For liver: deiodination was only measured up to stage 2 and in postmetamorphic animals; in contrast to intestine, T(4)ORD activity fell to low levels at stage 2 and was low during postmetamorphosis; T(4)IRD and T(3)IRD activities were very low and uninfluenced by developmental stage; T(3)ORD activity was undetectable. We conclude that (1) deiodination activity is usually much higher in intestine than in liver, (2) intestinal ORD and IRD activities change reciprocally so that ORD predominates in early metamorphosis but IRD predominates in mid and late metamorphosis, and (3) changes in intestinal deiodination may contribute to the characteristic depression of plasma T(4) and T(3) levels during spontaneous metamorphosis. J. Exp. Zool. 286:305-312, 2000.     

Apoptosis induced by hydrogen peroxide under serum deprivation and its inhibition by antisense c-jun in F-MEL cells

Under serum deprivation F-MEL cells die by apoptosis. We previously showed that apoptosis induced by serum deprivation was suppressed by inhibition of c-jun expression using antisense c-jun transfected cell line, c-junAS. To elucidate the underlying mechanisms we examined the species which is responsible for apoptosis under serum deprivation. When catalase and N-acetyl-L-cysteine (NAC) were included in the medium, cell death under serum deprivation was effectively suppressed in F-MEL cells. Intracellular generation of hydrogen peroxide (H(2)O(2)) was also detected under serum deprivation in parental F-MEL cells, but it was suppressed in c-junAS (+) cells, in which antisense c-jun was expressed and c-Jun protein expression was inhibited as shown by Western blot. When H(2)O(2) was directly applied to F-MEL cells at 3 mM, apoptotic cell death was induced, whereas it was suppressed in c-junAS (+) cells. Induction of apoptosis by H(2)O(2) and its inhibition by antisense c-jun was confirmed by detection of internucleosomal fragmentation of DNA, TdT-mediated dUTP nick end labeling (TUNEL)-positive cells and morphological alteration of nuclei. These results indicate that apoptosis induced by serum deprivation in F-MEL cells is mediated by H(2)O(2) and c-jun expression is essential to apoptosis induced by H(2)O(2) in F-MEL cells.     

The formation of choline O-sulphate by Pseudomonas C12B and other Pseudomonas species

Pseudomonas C(12)B and other Pseudomonas species released larger amounts of a (35)S-labelled metabolite into the medium when cultured on growth-limiting concentrations of Na(2)SO(4) as opposed to growth in SO(4) (2-)-sufficient media. The metabolite was found at all stages of the culture cycle of Pseudomonas C(12)B and maximum quantities occurred in stationary-phase culture supernatants. The metabolite was not detected when the bacterium was cultured on growth-limiting concentrations of potassium phosphate. The amount of the metabolite present in the medium greatly exceeded that which could be extracted from intact cells and, except for choline chloride, it was independent of the carbon source used for growth. If choline chloride was present in high concentration, then larger amounts of the metabolite were found in the culture medium. The metabolite was not detected extracellularly or intracellularly when the bacterium was grown in SO(4) (2-)-deficient media containing 5mm-l-cysteine. The same metabolite was also synthesized in vitro only when Pseudomonas C(12)B extracts were incubated with choline chloride, ATP, MgCl(2) and Na(2) (35)SO(4). The metabolite-forming system was not subject to repression by Na(2)SO(4) and was completely inhibited by 0.5mm-l-cysteine and activated by Na(2)SO(4) (up to 1.0mm). The metabolite was identified as choline O-sulphate by electrophoresis, chromatography and isotope-dilution analysis. Another (35)S-labelled metabolite was also detected in culture supernatants, but was not identified.     

椎间孔镜技术治疗腰椎间盘突出症的临床疗效及对患者预后的影响

目的:探讨椎间孔镜技术治疗腰椎间盘突出症的临床疗效及对患者预后的影响。方法:选择2012年9月-2014年9月在我院接受手术治疗的腰椎间盘突出症患者93例作为研究对象,根据手术方法不同,将所选研究对象分为椎间孔镜组(47例)和腰椎间盘切除组(46例)。椎间孔镜组患者采用经皮椎间孔镜手术治疗,腰椎间盘切除组患者采用显微内镜下后路腰椎间盘切除术治疗。观察并比较两组患者的手术时间、术中出血量、切口长度以及住院时间等,分别于手术前后采用主诉疼痛分级法(VRS)和视觉模拟法(VAS)评价临床疗效。结果:椎间孔镜组患者手术时间为(63.54±12.28)min、术中出血量为(10.39±2.91)m L、切口长度为(0.84±0.13)cm、住院时间为(6.25±1.48)d;腰椎间盘切除组患者手术时间为(58.82±10.47)min、术中出血量为(81.56±20.48)m L、切口长度为(1.92±0.35)cm、住院时间为(9.94±1.65)d;与腰椎间盘切除组比较,椎间孔镜组患者手术时间长、术中出血量少、手术切口小、住院时间短,差异均具有统计学意义(P0.05)。两组术后VRS及VAS评分均显著低于术前,差异具有统计学意义(P0.05);椎间孔镜组术后VRS及VAS评分均显著低于腰椎间盘切除组,差异均具有统计学意义(P0.05)。椎间孔镜组患者手术优良率(72.34%)显著高于腰椎间盘切除组(56.52%),差异具有统计学意义(P0.05)。结论:经皮椎间孔镜技术治疗腰椎间盘突出症的临床效果显著,不仅能够改善患者关节疼痛症状,而且手术对患者机体创伤小,有利于术后恢复。     

Effects of alpha-Hydroxy-2-Pyridinemethanesulfonic Acid on Photosynthetic Carbon Dioxide Uptake and Stomatal Movements in Excised Tomato Leaves

The effects of 10(-2)m alpha-hydroxy-2-pyridinemethanesulfonic acid (alphaHPMS) on the CO(2) compensation point, photosynthetic CO(2) uptake, CO(2) evolution into CO(2)-free air in light, and stomatal movement, in excised tomato leaves (Lycopersicon esculentum Mill. Eurocross BB-F(1) Hybrid) were studied. It was found that alpha-HPMS had a transient lowering effect on the CO(2) compensation point of treated leaves within the first 5 minutes of application. The net photosynthetic CO(2) uptake was inhibited by alpha-HPMS treatment. The inhibition increased with time and was enhanced in an O(2)-free atmosphere. The CO(2) evolution into CO(2)-free air in light was inhibited by alpha-HPMS. The inhibition was O(2)-dependent because the effect was observed only in 21% O(2) but not in O(2)-free N(2). Stomatal apertures were affected by alpha-HPMS, but the effect was transient and was observed 15 to 30 minutes after the application. The time course of this closure did not account for the observed inhibition of net CO(2) uptake.     

Expression of FGF2 and TGFalpha and testis morphology during testicular hypertrophy subsequent to hemicastration in the neonatal boar

The objective was to ascertain fibroblast growth factor-2 (FGF2), epidermal growth factor (EGF), and transforming growth factor-alpha (TGFalpha) mRNA expression and testis morphology during accelerated testicular growth after hemicastration in the neonatal boar. On Day 10 after birth (Day 0), boars were assigned to control (n = 28), no treatment; hemicastrated (n = 28), left testis removed. The right testis in both groups (n = 7) was removed on Days 5, 10, 15, and 20. Expression of mRNA for FGF2, EGF, and TGFalpha was determined by qRT-PCR using TaqMan. Testicular morphology was determined on Day 15. On Day 10, hemicastrated boars had a greater (P = 0.01) testis weight (6.2 +/- 0.8 g; mean +/- SEM) than controls (4.3 +/- 0.4 g) and on Day 15 testis weight in hemicastrated boars (8.8 +/- 0.8 g) was twice (P < 0.01) that of control boars (4.2 +/- 0.3 g). Seminiferous tubule volume was approximately doubled in hemicastrated boars (P < 0.01) and was associated with an increase (P < 0.01) in Sertoli cell number. Interstitial compartment volume was greater (P < 0.01) in hemicastrated boars. Leydig cell numbers were similar (P = 0.14) but volume was greater (P < 0.01) for hemicastrates. There were no differences (P > 0.05) between control and hemicastrated boars in TGFalpha or FGF2 expression on Day 5 or Day 10, and EGF was not detected. It was concluded that upregulation of TGFalpha or FGF2 expression is not a pre-requisite for enhanced testicular growth and increased Sertoli cell proliferation that occurs subsequent to hemicastration in the neonatal boar.     

Immunohistochemical expression of HGF, c-MET and transcription factor STAT3 in colorectal tumors

By immunohistochemistry, we have investigated the expression of hepatocyte growth factor (HGF), HGF-R or c-met and the transcritor factor STAT3 in a series of 80 colorectal tumours (40 adenomas and 40 adenocarcinomas). The expression of HGF, c-met and STAT3 was revealed in 40/40 (100%) of adenomas and in 26/40 (65%) of adenocarcinomas; the remaining 14/40 (35%) carcinomas expressed c-met but failed to express HGF and STAT3. Positive immunoreaction score was defined through the number of stained cells: low (1-10%), moderate (11-50%) and high (>51%). In adenomas, the HGF immunoreaction was high in 33 (82.5%) and moderate in 7 (17.5%); the c-met staining was high in 3 (7.5%) and moderate in 37 (92.5%); and the STAT3 reactivity was high in 25 (62.5%) and moderate in 15(37.5%). In carcinomas, the HGF immunoreaction was moderate in 21 (80.7%) and low in 5 (19.2%); the c-met staining was high in 14 (35%), moderate in 25 (62.5) and low in 1 (2.5%); and the STAT3 reactivity was moderate in 17 (65.3%) and low in 9 (34.6%). In both type of lesions, HGF and c-met showed a membranous and cytoplasmic location. In adenomas, STAT3 was detected in cytoplasm and nucleus and in carcinomas it was limited to cytoplasm. While the HGF/c-met/STAT3 expression in adenomas was significantly different from carcinomas (c2 = 17, p < 0.0001), no correlation was found among HGF, c-met, or STAT3 immunostaining with histotype or degree of dysplasia in adenomas and the same for histotype, grading or staging in carcinomas. These features, suggesting a role of the HGF/c-met/STAT3 signal in colon tumorigenesis, indicate that a reduced expression of HGF and c-met is associated to progression of adenoma into carcinoma.     

Kidney adaptation in nitric oxide-deficient Wistar and spontaneously hypertensive rats

We investigated the renal structural and functional consequences of nitric oxide (NO) deficiency co-treated with angiotensin-converting enzyme inhibitor (ACEi) in 20 adult male Wistar rats and 20 spontaneously hypertensive rats (SHR). The animals were separated into eight groups (n = 5) and treated for 30 days: Control, L-NAME (NO deficient group), Enalapril, L-NAME + Enalapril. The elevated blood pressure in NO deficient rats was partially reduced by enalapril. Serum creatinine was elevated in L-NAME-SHRs and effectively treated with enalapril. The proteinuria was significantly higher only in L-NAME-SHRs, and this was reduced by treatment with ACEi. The glomerular volume density (Vv(gl)) in L-NAME rats, both Wistar and SHR, was greater than in matched control rats, and enalapril treatment effectively prevented this Vv(gl) increase. No significant differences were observed in tubular volume density, Vv(tub), or tubular surface density, Sv(tub), in all Wistar groups. The Vv(tub) was smaller in L-NAME-SHRs than in control SHRs, and this tubular alteration was not prevented by enalapril. The Sv(tub) was not different among the SHR groups. In Wistar rats no changes were seen in vascular surface density, but a greatly increased cortical vascular volume density was seen in the enalapril treated rats. The vascular length density was greatly diminished in NO deficient rats that was effectively prevented with enalapril treatment. The vascular cortical renal stereological indices are normally reduced in SHRs. Administration of enalapril, but not L-NAME, changed this tendency. However, enalapril was not totally effective in preventing vascular damage in SHR NO deficient animals.     

Contraction-induced increases in Na+-K+-ATPase mRNA levels in human skeletal muscle are not amplified by activation of additional muscle mass

The present study tested the hypothesis that exercise with a large compared with a small active muscle mass results in a higher contraction-induced increase in Na(+)-K(+)-ATPase mRNA expression due to greater hormonal responses. Furthermore, the relative abundance of Na(+)-K(+)-ATPase subunit alpha(1), alpha(2), alpha(3), alpha(4), beta(1), beta(2), and beta(3) mRNA in human skeletal muscle was investigated. On two occasions, eight subjects performed one-legged knee extension exercise (L) or combined one-legged knee extension and bilateral arm cranking (AL) for 5.00, 4.25, 3.50, 2.75, and 2.00 min separated by 3 min of rest. Leg exercise power output was the same in AL and L, but heart rate at the end of each exercise interval was higher in AL compared with L. One minute after exercise, arm venous blood lactate was higher in AL than in L. A higher level of blood epinephrine and norepinephrine was evident 3 min after exercise in AL compared with L. Nevertheless, none of the exercise-induced increases in alpha(1), alpha(2), beta(1), and beta(3) mRNA expression levels were higher in AL compared with L. The most abundant Na(+)-K(+)-ATPase subunit at the mRNA level was beta(1), which was expressed 3.4 times than alpha(2). Expression of alpha(1), beta(2), and beta(3) was less than 5% of the alpha(2) expression, and no reliable detection of alpha(3) and alpha(4) was possible. In conclusion, activation of additional muscle mass does not result in a higher exercise-induced increase in Na(+)-K(+)-ATPase subunit-specific mRNA.     

松花江干流大型底栖动物群落结构与水质生物评价

于2010年春季（4-5月）、夏季（7-8月）和秋季（9-11月）,对松花江干流大型底栖动物群落结构进行调查研究,并利用生物指数对松花江干流水质进行评价.共采集到大型底栖动物16目36科116种,其中水生昆虫种类最多,为74种,属6目21科,占总数63.8%,年平均密度为66.80 ind·m^-2、生物量为24.30 g·m^-2.春、夏、秋季的平均密度以春季最高 (90.52 ind·m^-2),秋季(61.26 ind·m^-2)次之,夏季(48.63 ind·m^-2)最低;平均生物量以秋季最高(35.35 g·m^-2),夏季(23.12 g·m^-2)次之,春季(14.41 g·m^-2)最低.Shannon指数、Pielou均匀度指数、Simpson指数均以春季最高,夏季与秋季相近.各断面微生境共有种不多, 物种相似性不高,最大仅为60%;功能摄食群种类数相近,共有撕食者26种,收集者32种,刮食者28种,捕食者30种.采用BI生物指数和FBI生物指数对松花江干流水质的评价结果基本一致,并与化学监测结果基本吻合.松花江干流哈尔滨断面以上水质一般,哈尔滨以下断面水质在不同时期处于污染或严重污染状态.推测大顶子山航电枢纽的修建已对大型底栖动物的物种组成、群落结构造成了较大影响.     

台湾海峡夏秋季游泳动物资源分布及群落结构

根据夏季和秋季在台湾海峡进行的底拖网调查数据,分析了台湾海峡游泳动物资源密度指数分布及群落结构.结果表明,台湾海峡夏季平均资源密度指数高于秋季,分别为8.50和6.94kg·h^-1;夏秋季出现游泳动物种类分别为80种和91种,秋季丰富度、多样性、均匀度均高于夏季,夏秋季平均多样性指数分别为2.0466和2.3964;相对重要性指数IRI大于200的优势种夏季有5种,为带鱼、发光鲷、短尾大眼鲷、花斑蛇鲻、中国枪乌贼,秋季有6种,为带鱼、七星底灯鱼、刺鲳、中国枪乌贼、蓝圆_鲹、鹿斑鲾;夏季优势种的聚集强度比秋季强.     

Effect of H(2)-CO(2) on Methanogenesis from Acetate or Methanol in Methanosarcina spp

Growth of Methanosarcina sp. strain 227 and Methanosarcina mazei on H(2)-CO(2) and mixtures of H(2)-CO(2) and acetate or methanol was examined. The growth yield of strain 227 on H(2)-CO(2) in complex medium was 8.4 mg/mmol of methane produced. Growth in defined medium was characteristically slower, and cell yields were proportionately lower. Labeling studies confirmed that CO(2) was rapidly reduced to CH(4) in the presence of H(2), and little acetate was used for methanogenesis until H(2) was exhausted. This resulted in a biphasic pattern of growth similar to that reported for strain 227 grown on methanol-acetate mixtures. Biphasic growth was not observed in cultures on mixtures of H(2)-CO(2) and methanol, and less methanol oxidation occurred in the presence of H(2). In M. mazei the aceticlastic reaction was also inhibited by the added H(2), but since the cultures did not immediately metabolize H(2), the duration of the inhibition was much longer.     

Effects of insulin-induced hypoglycaemia on the fate of glucose carbon atoms in the mouse

1. [U-(14)C]Glucose was injected into mice and the distribution of (14)C in various chemical fractions of the whole body was determined at times from 15min. to 8hr. after injection. 2. At 1hr. after injection 31.8% of the recovered (14)C was found in the expired air and 26.7% was found in the isolated glycogen, lipids, proteins, nucleic acids and in other acid-insoluble carbon compounds (;residual (14)C'). The rest (41.5%) was combined in acid-soluble substances. 3. When insulin was injected 5min. or 1hr. before injection of [U-(14)C]glucose, and the mouse was killed 1hr. later, the (14)C content of expired air, glycogen, protein and ;residual (14)C' was not significantly affected; but the incorporation of (14)C into lipids was increased two- to three-fold. 4. Chromatography of the lipids on silicic acid columns and by thin-layer chromatography showed that the main effect of insulin injection was to increase the incorporation of (14)C into fatty acids. 5. A significant increase of (14)C after insulin injection was also found in a glyceride in which the (14)C was combined in glycerol.     

The speed of soil carbon throughput in an upland grassland is increased by liming

In situ (13)C pulse labelling was used to measure the temporal and spatial carbon flow through an upland grassland. The label was delivered as (13)C-CO(2) to vegetation in three replicate plots in each of two treatments: control and lime addition. Harvests occurred over a two month period and samples were taken along transects away from the label delivery area. The (13)C concentration of shoot, root, bulk soil, and soil-respired CO(2) was measured. There was no difference in the biomass and (13)C concentration of shoot and root material for the control and lime treatments meaning that the amount of (13)C-CO(2) assimilated by the vegetation and translocated below ground was the same in both treatments. The (13)C concentration of the bulk soil was lower in the lime treatment than in the control and, conversely, the (13)C concentration of the soil-respired CO(2) was higher in the lime. Unlike the difference in bulk soil (13)C concentration between treatments, the difference in the (13)C concentration of the soil-respired CO(2) was obvious only at the delivery site and primarily within 1 d after labelling. An observed increase in the abundance of mycorrhizal fungi in the lime treatment was a possible cause for this faster carbon throughput. The potential key role of mycorrhizas in the soil carbon cycle is discussed. The importance of a better understanding of soil processes, especially biological ones, in relation to the global carbon cycle and environmental change is highlighted.