Zymosan-induced luminol-amplified chemiluminescence of whole blood phagocytes in experimental and human hyperthyroidism

Luminol-amplified CL of whole blood phagocytes was studied in rats given 3 consecutive doses of 0.1 mg L-triiodothyronine T₃/kg or in hyperthyroid patients, after stimulation by zymosan. In both cases, CL was significantly increased, in effect which was produced independently of the opsonization of the zymosan particles and markedly inhibited by azide. The in vitro addition of T₃ or L-thyroxine (T₄) to whole blood phagocytes from normal rats did not modify the opsonized zymosan-dependent CL, when assayed at the concentrations found in eutrhyroid subjects or in hyperthyroid patients. Administrations of propylthiouracil (400 mg/day for 2–3 months) to hyperthyroid patients reduced the CL response observed prior to treatment, to values comparable to those found in the euthyroid group. These data indicate that hyperthyroidism elicits an enhanced respiratory burst activity of whole blood phagocytes, probably related to adaptive changes induced by thyroid hormone on the mieloperoxidase-H₂O₂ system, rather than to direct actions of the hormone molecule or changes in the opsonic capacity of plasma.     

Nyctohemeral Rhythms of Gonadal, Thyroid and Pineal Function in the Hyperprolactinemic Male Rat

In young adult male rats bearing a donor anterior pituitary gland grafted for 3 weeks under a kidney capsule, serum prolactin (PRL) concentrations were elevated and exhibited a rhythm with the highest values in the light phase. Serum PRL in control animals did not exhibit a significant rhythm. Eutopic pituitary PRL content, manifesting a biphasic (12-hr) rhythm with crests during the day and night in controls, exhibited a similar pattern in grafted rats though an overall reduction in pituitary PRL content was seen in the grafted animals. Neither the normal biphasic serum testosterone rhythm nor the normal 24-hr rhythm (nocturnal surge) of pineal N-acetyltransferase activity and melatonin content were altered in the hyperprolactinemic rats. Serum thyroxine (T₄) and triiodothyronine (T₃) and their free indices (FT₄ I, FT₃ I) and serum thyrotropin (TSH) were highest during the day in controls and grafted rats and a 12-hr rhythmic component was detected in data for these variables. In the grafted animals, the 12-hr component was reflected in an additional peak at night detectable by testing of means. The overall serum T₄ FT₄ I, and TSH levels were lower in grafted rats though overall T₃ and FT₃I levels did not differ between grafted and controls. T₃ uptake (T₃ U) values were similar between controls and grafted rats, in both cases exhibiting a fall during the night. Changes in serum thyronines could not be explained by changes in serum binding as assessed by the T₃U₃ and thus may represent changes in thyroidal secretion of T₄. The rhythm in serum PRL of grafted rats suggests the presence of rhythmic circulating factor(s) capable of influencing ectopic lactotrophs. The reduced eutopic pituitary PRL content suggests a role for PRL in influencing eutopic lactotrophs in the pituitary-grafted hyperprolactinemic male rat model. Though circulating testosterone and pineal melatonin synthesis were not altered in this model, thyroid function appeared to be so.     

Kupffer Cell Function in Thyroid Hormone-Induced Liver Oxidative Stress in the Rat

The influence of thyroid hormone (L-3, 3', 5-triiodothyronine, T₃) on Kupffer cell function was studied in the isolated perfused rat liver by colloidal carbon infusion. Rates of carbon uptake were determined from the influent minus effluent concentration difference and the flow rate, and the respective carbon-induced respiratory activity was calculated by integration of the area under the O₂ curves during carbon infusion. In the concentration range of 0.2 to 2.0 mg of carbon/ml, livers from euthyroid rats exhibited a sigmoidal-type kinetics of carbon uptake, with a Vmax of 4.8 mg/g liver/min and a concentration of 0.82 mg/ml for half-maximal rate; carbon-induced O₂ uptake presented a hyperbolic-type kinetics, with a Vmax of 4.57 μmol of O₂/g liver and a Km of 0.74 mg of carbon/ml, which significantly correlates with the carbon uptake rates. Light-microscopy showed that carbon was taken up exclusively by non-parenchymal cells, predominantly by Kupffer cells. Thyroid calorigenesis was found in parallel with increased rates of hepatic O₂ consumption and thiobarbituric acid reactive substances (TBARS) formation, glutathione (GSH) depletion, and higher sinusoidal lactate dehydrogenase (LDH) efflux compared to control values. In the concentration range of 0.25 to 0.75 mg/ml, carbon infusion did not modify liver LDH efflux in control rats, while it was significantly enhanced in T₃-treated animals. In this latter group, higher carbon concentrations (1 and 1.3 mg/ml) led to loss of viability of the liver. At 0.25 to 0.75 mg of carbon/ml, both the rates of carbon uptake and the associated carbon-induced respiratory activities were significantly increased by T₃ treatment, effects that were abolished by pretreatment of the rats with gadolinium chloride (GdCl₃). In addition, GdCl₃ decreased by 50% the changes induced by T₃ in hepatic GSH content and TBARS formation. It is concluded that hyperthyroidism enhances Kupffer cell function, correlated with the increased number of liver macrophages observed histologically, which may represent an alternate source of reactive O₂ species to that induced in parenchymal cells, thus contributing to the enhanced oxidative stress status developed.     

Estrogen antagonism on T3 and growth hormone control of the liver microsomal low-affinity glucocorticoid binding site (LAGS)

Male rat liver microsomes contain a low-affinity glucocorticoid binding site (LAGS) capable of binding all natural glucocorticoids and progesterone with a K_d from 20 to 100 nM. The LAGS level is under endocrine control by T₃, glucocorticoids and GH. These hormones act synergistically at physiological concentrations to increase the LAGS level. Since female rats show a LAGS level that is much lower than the males (0.15 vs 23 pmol/mg protein, respectively), here we investigated whether estradiol could decrease the LAGS in the male rat. Orchiectomized (OX) male rats showed a higher LAGS level than intact rats. This effect was reversed by implanting a Sylastic capsule containing testosterone. When the OX rats were implanted for 20 days with estrogen capsules that provided an estradiol level in serum of 40 pg/ml, their LAGS level decreased from 23 to 0.2 pmol/mg protein. This effect was not observed in intact male rats and can be partially reversed by testosterone implants into OX rats. Both hypophysectomized male rats and hypothyroid-orchiectomized male rats showed very low levels of LAGS. Administration of physiological doses of GH and/or T₃ to these rats greatly increased their LAGS level (from 0.3 to 15 and 16 pmol/mg protein, respectively). Implantation of estrogen capsules to these rats two weeks prior to starting treatment completely inhibited the increase in the LAGS level in response to T₃, and significantly decreased the response to hGH, and to a combination of hGH and T₃. These results suggest that physiological estradiol levels can antagonize the LAGS induction by T₃ and hGH in the male rat, and could be responsible for the low level of LAGS in the female rat. Moreover, estrogen capsules also inhibited the increase in the body and hepatic weights observed after hGH treatment, which suggests a powerful inhibitory effect of low estradiol levels on the male rat liver functions under regulation by T₃ and/or GH.     

Metabolic effects of thyroid hormones at a low temperature in the snake

1. 1.|The metabolic role of the thyroid gland was studied in intact snakes, Naja naja and Ptyas korros treated with tri-iodo-thyronine (T₃) and thyroxine (T₄) and in thyroidectomized (Tx) N. naja kept at 21°C by analyzing tissue composition and glycogen phosphorylase a activity.

2. 2.|Liver weight was unaffected by thyroid hormone injection in both species but decreases in liver glycogen followed T₃ or T₄ injection, and there was an increase in liver glycogen in N. naja. These changes in liver glycogen were accompanied by a decrease in glycogen phosphorylase a activity with T₃ injection. T₃ decreased muscle glycogen in Ptyas and Tx increased it in N. naja.

3. 3.|T₃ increased % liver lipid in Ptyas but not in Naja.

4. 4.|Between species, there were differences in liver weight, blood glucose level, cholesterol level and % muscle lipid.

5. 5.|The results showed that thyroid hormones affected carbohydrate and lipid metabolism at a low temperature of 21°C, although the significance is not known.

Annona squamosa seed extract in the regulation of hyperthyroidism and lipid-peroxidation in mice: Possible involvement of quercetin

Annona squamosa (Custard apple) seeds are generally thrown away as waste materials. The extract of these seeds was evaluated for its possible ameliorative effect in the regulation of hyperthyroidism in mouse model. Serum triiodothyronine (T₃), thyroxine (T₄) concentrations, hepatic glucose-6-phospatase (G-6-Pase) and 5′-mono-deiodinase (5′DI) activity were considered as the end parameters of thyroid function. Simultaneously hepatic lipid peroxidation (LPO), superoxide dismutase (SOD) and catalase (CAT) activities were investigated to observe its hepatotoxic effect, if any.

L-T₄ administration (0.5 mg/kg/d for 12 days, i.p.) increased the levels of serum T₃ and T₄, activity of hepatic G-6-Pase, 5′DI and LPO with a parallel decrease in SOD and CAT activities. However, simultaneous administration of the Annona seed extract (200 mg/kg) or quercetin (10 mg/kg) to T₄-induced hyperthyroid animals for 10 days, reversed all these effects indicating their potential in the regulation of hyperthyroidism. Further, the seed extract did not increase, but decreased the hepatic LPO suggesting its safe and antiperoxidative nature. Quercetin also decreased hepatic LPO. When relative efficacy was compared with that of propyl thiouracil (PTU), a standard antithyroidic drug, experimental seed extract appeared to be more effective. Phytochemical analyses including HPLC revealed the presence of quercetin in the seed extract and the results on the effects of quercetin suggested the involvement of this phytochemical in the mediation of antithyroidal activity of Annona squamosa seed extract.     

稗属杂草对水稻生长发育和产量的影响

以新两优6号(籼稻)和南粳46(粳稻)为材料,自水稻移栽至成熟分别与无芒稗(T₁)、稗(T₂)、西来稗(T₃)和光头稗(T₄)共生,稗草密度为6株·m^-2,以无稗草水稻处理为对照,研究不同稗草对水稻生长发育和产量的影响.结果表明：与对照相比,不同稗草对水稻的干扰表现不同,T₁、T₂、T₃处理使籼稻产量分别下降19.2%、10.8%、21.9%,使粳稻产量分别下降39.7%、25.3%、47.3%,但T₄处理对2个水稻品种的产量均无显著影响.水稻和稗草共生过程中,T₁、T₂和T₃处理显著降低了水稻成熟期的干物质积累量及灌浆期的剑叶光合速率、根系氧化力和籽粒ATP酶活性,降低幅度为T₃>T₁>T₂,T₄处理与对照差异不显著;各处理对水稻最终分蘖数和株高均无显著影响.表明4种稗草对水稻生长的影响由强到弱表现为：T₃>T₁>T₂>T₄,稻 稗共生时水稻剑叶光合速率、根系氧化力和籽粒ATP酶活性降低是导致水稻生产力下降的重要原因.     

Effects of Acacia nilotica, A. polyacantha and Leucaena leucocephala leaf meal supplementation on performance of Small East African goats fed native pasture hay basal forages

Optimal utilisation of tannin-rich browse tree fodders including Acacia spp. foliages as crude protein (CP) supplements to ruminants in the tropics is limited by less available information on their feed nutritive potential. Two studies were conducted to: (1) determine rate and extent of ruminal dry matter (DM) degradability (DMD) and (2) investigate effect of sun-dried Acacia nilotica (NLM), A. polyacantha (PLM) and Leucaena leucocephala leaf meal (LLM) supplementation on growth performance of 20 growing (7–9 months old) Small East African male goats (14.6 ± 0.68 kg) fed on native pasture hay (NPH) basal diet for 84 days in a completely randomised design experiment in north-western Tanzania. The goats were randomised into four treatment groups consisting of five animals each. Three supplement diets: 115.3 g NLM (T₂), 125.9 g PLM (T₃) and 124.1 g LLM (T₄), which was used as a positive control, were supplemented at 20% of the expected DM intake (DMI; i.e., 3% body weight) to the three animal groups fed on NPH (basal diet) compared to the animals in a control group that were fed on NPH without browse supplementation (T₁).

NPH had significantly the lowest (P < 0.05) CP of 45.5 g kg⁻¹ DM compared to NLM, PLM and LLM (159, 195 and 187 g kg⁻¹ DM, respectively). NPH had higher (P < 0.05) fibre fractions; lower ruminal DM degradability characteristics and ME than NLM, PLM and LLM. Supplementation of the animals with browse resulted to (P < 0.05) higher average daily weight gains (ADG) of 157.1 g day⁻¹ in T₄ than the animals fed on T₂ (114.3 g day⁻¹) and T₃ (42.9 g day⁻¹), and even to those fed on T₁ (control), which lost weight (−71.4 g day⁻¹). Improved weight gains were mainly due to corrected feed nitrogen (N) or CP due to supplementation of the animals with browse fodder. Too low CP of the NPH would not meet the normal requirements of CP (80 g CP kg⁻¹ DM) for optimal rumen microbial function in ruminants. Higher ADG due to LLM (T₄) and NLM (T₂) supplementation suggest optimised weight gains due to browse supplementation (20% of expected DMI); while lower weight gains from supplementation with PLM (T₃) indicate the possible utilisation of A. polyacantha leaves to overcome weight losses especially during dry seasons.     

冬小麦高产高效群体的年际间稳产性能

以冬小麦品种‘泰农18’为试验材料,设置传统农民管理习惯的农户模式(T₁)、不计肥水和人工等投入以获得高产的高产模式(T₂)和优化种植密度、播期、肥水管理运筹的高产高效模式(T₃)3种种植模式,于2012年10月—2016年7月连续4个小麦生育季,研究了不同种植模式小麦主茎与分蘖成穗特性、不同年份的光合有效辐射截获、利用、光合产物分配等光能利用特性和产量差异,结合年际间的光、温、水等生态因子分布差异,分析了高产高效群体的稳产性能.结果表明: 冬小麦不同生育时期内的光、温、降雨等生态因子的总量和各生育时期分布存在较大变异.T₁、T₂、T₃模式主茎穗的比例分别为38.9%、58.7%、66.9%,表明T₁、T₂、T₃模式在群体结构构建上分别是以分蘖穗为主、主茎穗和分蘖穗并重、主茎穗为主.T₂模式的生物量和产量最高,T₁最低,T₃模式自孕穗期之后,尤其是在开花14 d后仍能维持较高的叶面积指数、光能截获率和截获量、群体光合速率,并具有较高的干物质分配能力,使其在干物质积累相对偏低的情况下仍可获得高产.T₃模式花后的叶面积指数、光能截获率和截获量以及光合速率等的年际间极差、标准差、变异系数均小于T₁和T₂模式,由此也保证了T₃模式生物产量的稳定.相关分析表明,以主茎成穗为主的T₃种植模式能够有效应对年际间气候变化并实现稳产,关键是具有年际间稳定的生物产量.     

不同水肥一体化方式对苹果氮素吸收利用特性及产量和品质的影响

以‘嘎啦/八棱海棠’为试材,借助¹⁵N同位素示踪技术,研究了撒施(T₁)、滴灌施氮(T₂)和渗灌施氮(T₃)对嘎啦苹果氮素吸收利用、分配特性和产量品质的影响,以期进一步完善苹果园水肥一体化技术,挖掘提高氮素利用率的途径。结果表明: T₃处理苹果叶片的叶面积、叶绿素和氮含量显著高于T₁和T₂处理。各时期土壤矿化氮(N_min)含量在20~40 cm土层表现为T₃＞T₂＞T₁处理,在0~20 cm土层表现为T₂＞T₃＞T₁处理。同一器官的Ndff值(树体各器官从肥料中吸收到的¹⁵N占该器官全氮量的比例)在各时期均以T₃处理最高,T₂其次,T₁处理最低。果实成熟期的树体¹⁵N利用率表现为T₃＞T₂＞T₁处理,其中T₃处理的树体¹⁵N利用率为24.2%,分别是T₂和T₁处理的1.19和1.65倍。果实成熟期T₁处理的¹⁵N分配率在营养器官最高,T₂处理在贮藏器官最高,T₃处理在生殖器官最高。各处理的单果重、产量、可溶性固形物、硬度、可溶性糖及糖酸比均以T₃处理最高,T₂其次,T₁处理最低。渗灌施氮处理显著促进了嘎啦苹果树体叶片生长和氮素利用,并提高了果实产量和品质。     

残次苹果发酵产物对连作土壤环境及‘平邑甜茶’幼苗生长的影响

在盆栽条件下,研究残次苹果发酵产物对连作土壤环境及平邑甜茶幼苗生长的影响,为减轻苹果连作障碍提供理论依据。试验以连作土壤为对照(CK),设置溴甲烷灭菌连作土壤(T₁)、连作土壤施加苹果发酵产物(T₂)、连作土壤施加灭菌苹果发酵产物(T₃)处理,测定了土壤和平邑甜茶幼苗的相关指标。结果表明: T₁、T₂、T₃能显著促进平邑甜茶幼苗的生长,其中以T₁和T₂的效果较好,其根系呼吸速率、株高、地径、鲜质量、干质量分别比CK提高了107.3%、50.6%、42.4%、171.7%、225.3%和104.4%、50.6%、42.3%、171.8%、225.5%。T₂和T₃提高了连作土壤中养分转化相关酶的活性,过氧化氢酶、脲酶、中性磷酸酶和蔗糖酶活性分别比CK提高了44.5%、169.5%、23.4%、169.3%和23.7%、72.6%、1.5%、121.5%;T₁处理的过氧化氢酶和蔗糖酶活性与CK无显著差异,脲酶和中性磷酸酶活性分别降低了40.8%和41.6%。T₂土壤铵态氮、硝态氮、速效磷和速效钾含量分别较CK提高了18.6%、50.6%、14.0%和36.7%;T₃只提高了速效氮的含量,铵态氮和硝态氮含量分别提高了7.0%和23.6%;T₁与CK相比速效养分含量有所降低。T₁和T₂显著降低了土壤放线菌和真菌数量,增加了细菌数量;T₃处理的细菌、放线菌和真菌数量均较CK显著降低。实时荧光定量PCR分析发现,T₁、T₂和T₃处理的层出镰孢菌、串珠镰孢菌、腐皮镰孢菌和尖孢镰孢菌基因拷贝数均较CK有不同程度的降低。表明苹果发酵产物处理能抑制连作土壤病原菌,改善土壤环境,促进平邑甜茶幼苗生长,可作为一种减轻苹果连作障碍的方法。     

Interaction of thyroid hormone and steroidogenic acute regulatory (StAR) protein in the regulation of murine Leydig cell steroidogenesis

The steroidogenic acute regulatory (StAR) protein, a novel phosphoprotein, is a crucial factor involved in intramitochondrial cholesterol transportation, the rate-limiting step in steroidogenesis. The present investigations were undertaken to elucidate involvement of thyroid hormone and StAR protein in the regulation of steroidogenesis in mouse Leydig cells. Treatment of cells with triiodothyronine (T₃) coordinately augmented the levels of StAR protein, StAR mRNA, and steroid production, and these responses were progressively dependent on expression of steroidogenic factor 1 (SF-1). With regard to steroidogenesis and StAR expression, the T₃ response requires both on-going mRNA and protein synthesis. In addition, the effects of T₃ were acutely modulated at the steroidogenic machinery and luteinizing hormone receptor (LHR) function, while these levels were suppressed following longer periods of exposure to T₃. Furthermore, the inhibition of SF-1 expression by DAX-1 markedly abolished T₃-mediated StAR expression in a time frame, which was consistent with decreased steroid biosynthesis. Specific involvement of SF-1 was further confirmed by assessing the 5′-flanking region of the mouse StAR gene, which identified a region between −254 and −110 bp that was essential for T₃ function. Importantly, it was found that the SF-1 binding site at position −135 bp of the 5′-flanking region was greatly involved in T₃-mediated reporter activity. Electrophoretic mobility shift assays (EMSA) also demonstrated involvement of SF-1 in T₃ function. The relevance of T₃-mediated LHR function was investigated in mice rendered hypo-and hyperthyroid, which accounted for up-regulation in the former and down-regulation in the latter group, respectively. These findings demonstrate a key role of thyroid hormone in maintaining mouse Leydig cell function, where thyroid hormone and StAR protein coordinately regulate steroid hormone biosynthesis.     

不同冬季覆盖作物对稻田甲烷和氧化亚氮排放的影响

采用静态箱-气相色谱法对不同冬季覆盖作物处理［免耕直播黑麦草-双季稻(T₁)、免耕直播紫云英 双季稻(T₂)、翻耕移栽油菜-双季稻(T₃)、免耕直播油菜-双季稻(T₄)和冬闲-双季稻(CK)］下稻田甲烷（CH₄）和氧化亚氮（N₂O）排放进行观测,分析了不同冬季覆盖作物对稻田CH₄和N₂O排放的影响.结果表明：在冬季作物生长期,不同冬季覆盖作物稻田CH₄和N₂O总排放量与对照（CK）的差异均达到极显著水平（P<0.01）;T₃和T₁处理的稻田CH₄和N₂O排放量最高,其CH₄排放量分别为0.88 和0.60g·m^-2,N₂O排放量分别为0.23 和0.20 g·m^-2;冬季作物还田后,各处理早、晚稻田CH4排放量均明显高于对照.早稻田CH₄排放量最高的为T₁和T₂处理,分别达21.70和20.75 g·m^-2;晚稻田CH₄排放量最高的为T₃和T₄处理,分别为58.90和54.51 g·m^-2.各处理早、晚稻田N₂O总排放量均显著高于对照,T₁、T₂、T₃和T₄处理的早稻田N₂O总排放量分别比对照增加53.7%、12.2%、46.3%和29.3%,晚稻田分别比对照增加28.6%、3.8%、34.3%和27.6%.     

烟草形态和光合生理对减弱UV-B辐射的响应

在云南较高海拔烟区,通过大棚覆膜减弱UV-B辐射,研究了烟草品种K326生理成熟期、工艺成熟期和生理成熟向工艺成熟的过渡期形态和光合生理对减弱UV-B辐射(T₁ 75.74%、T₂ 70.08%、T₃ 30.39%)的响应.结果表明： 减弱UV-B辐射显著增加了K326的茎高和节间距,在T₂下茎高和节间距较大;与自然环境处理（CK）相比,T₁和T₂降低了K326的净光合速率、同化能力、水分利用率、内在水分利用率、光合色素和类黄酮含量及比叶重等,但T₁各指标大于T_2.影响T₁和T₂净光合速率的因素有气孔因素和非气孔因素,以非气孔因素为主,气孔调节能力较低导致的蒸腾速率增大是造成两处理水分利用率较低的主要原因.T₃处理在生理成熟期和过渡期对净光合速率、同化能力、水分利用率、内在水分利用率和光合色素均有一定的促进作用,而比叶重和类黄酮则处于最低水平,工艺成熟期的光合色素降解也较其他处理快.     

温度驯化对布氏田鼠肝脏温敏瞬时受体电位通道蛋白表达的影响

肝脏是哺乳动物基础代谢产热的关键器官。温敏瞬时受体电位通道蛋白(Thermosensitive transient receptor potential channels,Thermo-TRPs)参与了调控肝细胞的生理功能。为了解Thermo-TRPs是否参与肝脏的代谢产热,以成年布氏田鼠(Lasiopodomys brandtii)为研究对象,测定了不同驯化温度下6种Thermo-TRPs在肝脏中的表达,分析其与肝脏产热相关蛋白和信号通路蛋白的关系。结果显示：(1)与高温组相比,低温增加了肝脏解偶联蛋白1(uncoupling protein 1,UCP1)的表达;而与常温组相比,低温降低了肝脏解偶联蛋白3 (uncoupling protein 3,UCP3)的表达;(2) 6种Thermo-TRPs均在肝脏中表达,与高温组相比,低温显著降低了TRP vanilloid 4 (TRPV4)的表达,同时显著增加了腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)的表达;(3)低温显著增加了布氏田鼠血清三碘甲状腺原氨酸(T₃)...     

外源瘦素注射对昆明和大理地区大绒鼠适应性产热的影响

小型哺乳动物通过产热能力的调整来应对环境的胁迫。为探究外源瘦素对不同地区大绒鼠(Eothenomys miletus)适应性产热的影响,选取云南昆明和大理地区捕获的大绒鼠各14只,置于25℃±1℃,光周期为12L∶12D的环境中,每日腹腔注射瘦素,持续28 d。以LT502电子天平每两天测定大绒鼠的体重,采用食物平衡法每两天测定大绒鼠摄食量,以便携式呼吸代谢测量系统每7天测定静止代谢率(RMR)、非颤抖性产热(NST)。第28天处死动物后,采用酶联免疫吸附法测定线粒体蛋白含量、线粒体细胞色素c氧化酶(COX)活性、解偶联蛋白1(UCP1)含量、血清三碘甲状腺原氨酸(T3)、甲状腺素(T4)、瘦素水平以及促甲状腺激素释放激素(TRH)和促肾上腺皮质激素释放激素(CRH)水平。结果表明,注射瘦素后昆明和大理地区大绒鼠的体重和摄食量显著降低,RMR和NST增强,肝脏中线粒体蛋白含量和COX活性,褐色脂肪组织(BAT)中COX活性和UCP1含量,及血清T3、T4、T3/T4比值、TRH和CRH浓度均增加。瘦素水平与体重、摄食量呈负相关,血清T3水平与NST和UCP1含量呈正相关。此外,注射前昆...     

不同生育期持续干旱对玉米的影响及其与减产率的定量关系

为了探究不同生长阶段土壤水分含量持续下降过程对玉米生长发育和产量形成的影响,通过设置遮雨棚人工控水试验,分析不同生长阶段持续干旱条件下玉米株高、叶面积指数(LAI)、光合性能、地上生物量和产量等生理生态指标的动态变化.试验因素为控水时段和控水持续时间,从拔节普遍期开始分别控水20(T₁)和27 d(T₂),从抽雄普遍期开始控水20(T₃)和27 d(T₄),加上不控水对照(CK),共5个处理.结果表明: 持续干旱导致植株叶片卷曲、打绺,下部叶片衰老加快,对LAI影响较大,从而降低生物量的累积与籽粒产量.T₁～T₄处理结束时LAI分别为CK的74.9%、68.2%、60.5%和48.3%.玉米植株在经历持续控水后,叶片最大净光合速率(P_{n max})逐渐下降,T₁(T₃)和T₂(T₄)处理结束时P_{n max}分别降至CK的23%及不足10%,复水2周后,P_{n max}能恢复到CK的90%左右.T₁和T₂处理产量较CK分别下降18.5%和24.0%,T₃和T₄处理分别减产41.6%和45.8%.抽雄期持续干旱对玉米地上生物量及产量构成的影响大于拔节期干旱.干旱程度(D)能够定量表示土壤干旱状况,与玉米减产率存在线性定量关系,可通过计算D来预测玉米的减产情况.     

Interaction of checkpoint kinase 1 and the X-linked inhibitor of apoptosis during mitosis

Senescence marker protein-30 (SMP30) was originally identified as a novel protein in the rat liver, the expression of which decreases androgen-independently with aging. We have now characterized a unique property of SMP30, the hydrolysis of diisopropyl phosphorofluoridate (DFP), which is similar to the chemical warfare nerve agents sarine, soman and tabun. Hydrolysis of DFP was stimulated equally well by 1 mM MgCl₂, MnCl₂ or CoCl₂, to a lesser extent by 1 mM CdCl₂ but not at all by 1 mM CaCl₂. No ⁴⁵Ca²⁺-binding activity was detected for purified SMP30, suggesting that SMP30 is not a calcium-binding protein, as others previously stated. Despite the sequence similarity between SMP30 and a serum paraoxonase (PON), the inability of SMP30 to hydrolyze PON-specific substrates such as paraoxon, dihydrocoumarin, γ-nonalactone, and δ-dodecanolactone indicate that SMP30 is distinct from the PON family. We previously established SMP30 knockout mice and have now tested DFPase activity in their livers. The livers from wild-type mice contained readily detectable DFPase activity, whereas no such enzyme activity was found in livers from SMP30 knockout mice. Moreover, the hepatocytes of SMP30 knockout mice were far more susceptible to DFP-induced cytotoxicity than those from the wild-type. These results indicate that SMP30 is a unique DFP hydrolyzing enzyme in the liver and has an important detoxification effect on DFP. Consequently, a reduction of SMP30 expression might account for the age-associated deterioration of cellular functions and enhanced susceptibility to harmful stimuli in aged tissue.     

模拟酸雨对青冈光合及叶绿素荧光参数的影响

在重度酸雨(pH 2.5)、中度酸雨(pH 4.0)和弱酸性酸雨(pH 5.6)3个酸雨梯度下,研究地上酸雨、全淋酸雨、土壤酸雨3种处理方式对青冈幼苗叶绿素荧光和光合参数的影响,并以空白为对照.结果表明: 在重度酸雨条件下,地上酸雨处理显著阻碍青冈幼苗叶绿素合成,降低PSⅡ原初光能转化效率(F_v/F_m)、潜在活性(F_v/F_o)和实际光化学量子产量(Y),以及净光合速率(P_n)、蒸腾速率(T_r)等光合参数,提高光补偿点和暗呼吸速率,全淋酸雨处理下青冈幼苗受到抑制作用其次,而土壤酸雨处理对其有一定的促进作用;中度酸雨和弱酸性酸雨条件下,不同处理方式除暗呼吸速率(R_d)低于对照外,其余均高于对照,并且全淋酸雨＞土壤酸雨＞地上酸雨处理.可见,在重度酸雨条件下,地上酸雨处理对幼苗的抑制作用最强;中度和弱酸性酸雨条件下,全淋酸雨处理对于幼苗的促进作用最强.不同酸雨强度对青冈幼苗叶绿素相对含量(SPAD)、PSⅡ原初光能转化效率(F_v/F_m)、PSⅡ潜在活性(F_v/F_o)、实际光化学量子产量(Y)、净光合速率(P_n)、蒸腾速率(T_r)和最大净光合速率(A_max)影响显著,不同酸雨处理方式对幼苗SPAD、F_v/F_m、Y、P_n、T_r、A_max和光饱和点(LSP)影响显著,二者交互作用对SPAD、F_v/F_m、Y、P_n和A_max影响显著.