Two new species of <Emphasis Type="Italic">Parspina</Emphasis> Pearse, 1920 (Digenea: Cryptogonimidae) from freshwater fishes (Gymnotiformes) of the Paraná River basin in Argentina

Two new species of the cryptogonimid genus Parspina Pearse, 1920 are described from gymnotiform fishes of the Paraná River basin, P. carapo n. sp. from the banded knifefish Gymnotus carapo Linnaeus and P. virescens n. sp. from the glass knifefish Eigenmannia virescens (Valenciennes). Parspina carapo differs from P. virescens in the number of oral spines (32–39 vs 30–33) and their length (28–47 vs 16–28 μm), the distribution of tegumental spines and their anchorage, the types of sensory papillae on the body surface (three vs two types), the extent of body length posterior to the caeca (5 vs 13% of the total body length), the dimensions of the pars prostatica (52 × 34 vs 24 × 10 μm), and in the absence of a gonotyl (vs presence). Both P. carapo and P. virescens differ from P. bagre Pearse, 1920 and P. argentinensis (Szidat, 1954) in the number of oral spines (20–21 and 21–28 in the latter pair) and their length (28–32 and 35–60 μm), and in total body length. Additionally, the two new species differ from P. argentinensis in the arrangement of the vitelline follicles (one continuous band vs two groups on each side of the body) and in having a smaller pars prostatica (149 × 49 μm in the latter). Parspina carapo is the fifth intestinal helminth found in G. carapo, and P. virescens is the first found in E. virescens.     

Effects of ATP-sensitive Potassium Channel Regulators on Chloride Channels in the Sarcoplasmic Reticulum Vesicles from Rabbit Skeletal Muscle

The lipid bilayer technique was used to examine the effects of the ATP-sensitive K⁺ channel inhibitor (glibenclamide) and openers (diazoxide, minoxidil and cromakalim) and Cl⁻ channel activators (GABA and diazepam) on two types of chloride channels in the sarcoplasmic reticulum (SR) from rabbit skeletal muscle. Neither diazepam at 100 μm nor GABA at 150 μm had any significant effect on the conductance and kinetics of the 75 pS small chloride (SCl) channel. Unlike the 150 pS channel, the SCl channel is sensitive to cytoplasmic glibenclamide with K _i ∼ 30 μm. Glibenclamide induced reversible decline in the values of current (maximal current amplitude, I _max and average mean current, I′) and kinetic parameters (frequency of opening F _o , probability of the channel being open P _o and mean open time, T _o , of the SCl channel. Glibenclamide increased mean closed time, T _c , and was a more potent blocker from the cytoplasmic side (cis) than from the luminal side (trans) of the channel. Diazoxide increased I′, P _o , and T _o in the absence of ATP and Mg²⁺ but it had no effect on I _max and also failed to activate or remove the glibenclamide- and ATP-induced inhibition of the SCl channel. Minoxidil induced a transient increase in I′ followed by an inhibition of I _max, whereas cromakalim reduced P _o and I′ by increasing channel transitions to the closed state and reducing T _o without affecting I _max. The presence of diazoxide, minoxidil or cromakalim on the cytoplasmic side of the channel did not prevent [ATP] _cis or [glibenclamide] _cis from blocking the channel. The data suggest that the action(s) of these drugs are not due to their effects on the phosphorylation of the channel protein. The glibenclamide- and cromakalim-induced effects on the SCl channel are mediated via a ``flicker' type block mechanism. Modulation of the SCl channel by [diazoxide] _cis and [glibenclamide] _cis highlights the therapeutic potential of these drugs in regulating the Ca²⁺-counter current through this channel. Received: 2 September 1997/Revised: 20 March 1998     

What can we learn about the lipid vesicle structure from the small-angle neutron scattering experiment?

Small-angle neutron scattering (SANS) on the unilamellar vesicle (ULV) populations (diameter 500 and 1,000 Å) in D₂O was used to characterize lipid vesicles from dimyristoylphosphatidylcholine (DMPC) at three phases: gel L_β′, ripple P_β′ and liquid L_α. Parameters of vesicle populations and internal structure of the DMPC bilayer were characterized on the basis of the separated form factor (SFF) model. Vesicle shape changes from nearly spherical in the L_α phase to elliptical in the P_β′ and L_β′ phases. This is true for vesicles prepared via extrusion through pores with the diameter 500 Å. Parameters of the internal bilayer structure (thickness of the membrane and the hydrophobic core, hydration and the surface area of the lipid molecule) were determined on the basis of the hydrophobic–hydrophilic (HH) approximation of neutron scattering length density across the bilayer ρ(x) and of the step function (SF) approximation of ρ(x). DMPC membrane thickness in the L_α phase (T=30°C) demonstrates a dependence on the membrane curvature for extruded vesicles. Prepared via extrusion through 500 Å diameter pores, vesicle population in the L_α phase has the following characteristics: average value of minor semi-axis 266±2 Å, ellipse eccentricity 1.11±0.02, polydispersity 26%, thickness of the membrane 48.9±0.2 Å and of the hydrophobic core 19.9±0.4 Å, surface area 60.7±0.5 Ų and number of water molecules 12.8±0.3 per DMPC molecule. Vesicles prepared via extrusion through pores with the diameter 1,000 Å have polydispersity of 48% and membrane thickness of 45.5±0.6 Å in the L_α phase. SF approximation was used to describe the DMPC membrane structure in L_β′ (T=10°C) and P_β′ (T=20°C) phases. Extruded DMPC vesicles in D₂O have membrane thickness of 49.6±0.5 Å in the L_β′ phase and 48.3±0.6 Å in the P_β′ phase. The dependence of the DMPC membrane thickness on temperature was restored from the SANS experiment.     

沙质草地3种优势植物叶片光合生理对增温和降水减少的响应北大核心CSCD

以沙质草地优势物种猪毛蒿、胡枝子和糙隐子草为研究对象,利用开顶式生长室(OTC)模拟增温,研究降水减少20%、40%和60%与增温的交互作用对3种典型植物叶片光合气体交换特征及叶绿素荧光特征的影响,以揭示沙质草地3种优势植物对气候变化的响应规律。结果显示:(1)与自然温度相比,OTC模拟增温增加了猪毛蒿C_(i),显著降低了胡枝子G_(s)、P_(n)和T_(r)、糙隐子草G_(s)和P_(n)、猪毛蒿WUE和L_(s),也显著降低了猪毛蒿和胡枝子F_(v)/F_(m)和F_(v)/F_(o)。(2)无论增温与否,随着降水减少幅度的增加,猪毛蒿G_(s)和P_(n)呈下降趋势,且中度以上的干旱胁迫下(降水减少>40%)胡枝子和糙隐子草P_(n)显著低于对照。(3)在自然温度条件下,轻度干旱胁迫时(降水减少20%)猪毛蒿T_(r)显著低于对照,重度干旱胁迫时(降水减少60%)其WUE、F_(v)/F_(m)和F_(v)/F_(o)显著低于对照;重度干旱胁迫时,胡枝子C_(i)显著高于对照,差异幅度达10.7%,L_(s)显著低于对照,轻度干旱胁迫时(降水减少20%)其F_(v)/F_(m)和F_(v)/F_(o)显著高于中度以上的干旱胁迫;中度以上的干旱胁迫下糙隐子草T_(r)和G_(s)显著低于对照,重度干旱胁迫时,其C_(i)、F_(v)/F_(m)和F_(v)/F_(o)显著低于对照,WUE和L_(s)显著高于对照。(4)增温与降水减少交互作用下,所有处理猪毛蒿C_(i)均高于对照,差异幅度分别达4.5%,6.0%和8.4%;胡枝子T_(r)均显著低于对照,差异幅度达57.8%;重度干旱胁迫时猪毛蒿L_(s)和WUE显著低于对照,糙隐子草F_(v)/F_(m)和F_(v)/F_(o)随降水减少而降低,中度以上的干旱胁迫时其值显著低于对照。(5)相关性分析表明,3个优势物种的P_(n)与F_(v)/F_(m)和F_(v)/F_(o)均呈显著正相关关系,其中猪毛蒿和糙隐子草的P_(n)—F_(v)/F_(m)和P_(n)—F_(v)/F_(o)斜率明显高于胡枝子。研究表明,气候变暖会在一定程度上加剧降水减少对沙质草地3种群落优势物种光合作用的抑制。     

蛹虫草磷酸甲羟戊酸激酶和焦磷酸甲羟戊酸脱羧酶基因的功能分析

【目的】确定蛹虫草甲羟戊酸途径中的2个关键酶——磷酸甲羟戊酸激酶(CmErg8)和焦磷酸甲羟戊酸脱羧酶(CmErg19)的功能及其对麦角甾醇和虫草素含量的影响。【方法】通过生物信息学分析鉴定蛹虫草中CmErg8和CmErg19,并采用酵母互补确定其功能是否保守;以蛹虫草尿嘧啶营养缺陷型CmΔpyrG为背景菌株,利用农杆菌介导的转化方法对CmErg8和CmErg19进行过表达,观察其对麦角甾醇和虫草素含量的影响。【结果】CmErg8和CmErg19不能互补酵母erg8和erg19突变体的温度敏感表型;CmErg8和CmErg19过表达菌株中麦角甾醇和虫草素含量均有所增加,特别是CmErg19基因过表达可以使虫草素含量提升5倍左右。【结论】本研究揭示了蛹虫草CmErg8和CmErg19的功能,并且发现蛹虫草麦角甾醇合成通路基因可能会影响虫草素含量。     

Mutually exclusive distribution of the sap and eag S-layer genes and the lytB/lytA cell wall hydrolase genes in Bacillus thuringiensis

Recently, two Bacillus thuringiensis strains were reported to synthesize parasporal inclusion bodies made not of the expected crystal (Cry) proteins but rather of the surface layer proteins (SLP) Sap (encoded by sap) and EA1 (encoded by eag), respectively. Whether the presence of the sap and eag genes is restricted to these two B. thuringiensis strains or ubiquitous in B. thuringiensis is unknown. We report here the distribution of the sap and eag genes in B. thuringiensis. Strains in the Bacillus cereus group were added for comparison purposes. We show that sap and eag are either present in tandem in 35% of the B. thuringiensis strains analysed and absent in 65% of the strains. When absent, a different tandem, the lytB/lytA cell wall hydrolase genes, is present. The distribution of the sap and eag S-layer and the lytB/lytA cell wall hydrolase genes is not species-specific in B. thuringiensis, B. cereus and Bacillus weihenstephanensis. Bacillus anthracis and Bacillus mycoides harbor sap and eag but not lytB/lytA. The sap, eag and lytB/lytA genes were absent in Bacillus pseudomycoides. Clearly, the distribution of the sap and eag S-layer and the lytB/lytA cell wall hydrolase genes in B. thuringiensis and in the Bacillus cereus group is mutually exclusive. We also showed that two genes involved in cell wall metabolism, csaA and csaB, are present not only upstream of the sap and eag S-layer genes, but also upstream of the lytB/lytA tandem in strains where sap and eag are absent. Bootstrapped neighbor-joining trees were inferred from the translated amino acid sequences of sap, eag and the tandem lytB/lytA, respectively.     

桂西南岩溶区八种适生植物光合性状的变异与关联

为探究岩溶植物的光合生理适应机制，采用Li-6400XT便携式光合作用测量系统，对广西平果市岩溶区8种适生植物的叶片净光合速率(P_n)、气孔导度(G_s)、胞间CO₂浓度(C_i)、蒸腾速率(T_r)、水分利用效率(WUE)和气孔限制值(L_s)等光合特征参数进行了测定分析。结果表明：(1)6个光合特征参数在种内和种间均存在不同程度的变异，并且种内变异均大于种间变异。(2)G_s和T_r的变化主要来源于种间变异(46.72%～49.76%),而P_n、C_i、WUE和L_s变化主要来源于种内变异(48.66%～64.50%)。在生活型水平上，P_n、G_s和T_r的种内变异表现为常绿植物小于落叶植物，而C_i、WUE和L_s则相反。(3)各参数的种间变异均表现为落叶植...     

Improvement of the transfucosylation activity of α-l-fucosidase from Thermotoga maritima for the synthesis of fucosylated oligosaccharides in the presence of calcium and sodium

The influence of CaCl₂ and NaCl in the hydrolytic activity and the influence of CaCl₂ in the synthesis of fucosylated oligosaccharides using α-l-fucosidase from Thermotoga maritima were evaluated. The hydrolytic activity of α-l-fucosidase from Thermotoga maritima displayed a maximum increase of 67% in the presence of 0.8 M NaCl with water activity (a_w) of 0.9672 and of 138% in the presence of 1.1 M CaCl₂ (a_w 0.9581). In addition, the hydrolytic activity was higher when using CaCl₂ compared to NaCl at a_w of 0.8956, 0.9581 and 0.9672. On the other hand, the effect of CaCl₂ in the synthesis of fucosylated oligosaccharides using 4-nitrophenyl-fucose as donor substrate and lactose as acceptor was studied. In these reactions, the presence of 1.1 M CaCl₂ favored the rate of transfucosylation, and improved the yield of synthesis duplicating and triplicating it with lactose concentrations of 58 and 146 mM, respectively. CaCl₂ did not significatively affect hydrolysis rate in these reactions. The combination of the activating effect of CaCl₂, the decrement in a_w and lactose concentration had a synergistic effect favoring the synthesis of fucosylated oligosaccharides.

     

Effect of estrogen on the expression of GnRH and kisspeptin in the hypothalamus of rats during puberty

The aim of this study was to assess whether changes in kisspeptin and GnRH levels could be attributed to sex steroids at puberty onset. We used the ovariectomy (OVX) model in rats treated with 17β-estradiol (E₂; OVX + E₂), or oil (OVX + oil), and in intact rats treated with E₂ (intact + E₂) or oil only (intact + oil) to determine gene expression changes of Kiss1 and Gnrh1 in the hypothalamus and protein expression of kisspeptin and GnRH in the different areas of the hypothalamus. In the intact + E₂ and OVX + E₂ rats on the day of the onset of puberty, GnRH-immunoreactive (ir) cell numbers decreased (P < 0.05) in the arcuate nucleus but were increased in the preoptic area; Kisspeptin-ir cells increased (P < 0.05) in the arcuate nucleus, periventricular nucleus, and preoptic area; no difference (P > 0.05) was found in the paraventricularis nucleus for GnRH-ir or kisspeptin-ir cells. Additionally, levels of Kiss1 and Gnrh1 messenger RNA in the hypothalamus were significantly higher (P < 0.05) in the OVX + E₂ or intact + E₂ rats than in the OVX + oil or intact + oil animals, respectively. In the OVX + oil rats, OVX significantly increased (P < 0.05) levels of Gnrh1 and Kiss1 messenger RNA and the expression of GnRH and kisspeptin in the hypothalamus compared to intact + oil animals. These results suggest that kisspeptin and GnRH play major roles in modulating the activity of estrogen circuits at the onset of puberty.     

Influence of Trace Elements Mixture on Bacterial Diversity and Fermentation Characteristics of Liquid Diet Fermented with Probiotics under Air-Tight Condition

Cu²⁺, Zn²⁺, Fe²⁺ and I⁻ are often supplemented to the diet of suckling and early weaning piglets, but little information is available regarding the effects of different Cu²⁺, Zn²⁺, Fe²⁺ and I⁻ mixtures on bacteria growth, diversity and fermentation characteristics of fermented liquid diet for piglets. Pyrosequencing was performed to investigate the effect of Cu²⁺, Zn²⁺, Fe²⁺ and I⁻ mixtures on the diversity, growth and fermentation characteristics of bacteria in the liquid diet fermented with Bacillus subtilis and Enterococcus faecalis under air-tight condition. Results showed that the mixtures of Cu²⁺, Zn²⁺, Fe²⁺ and I⁻ at different concentrations promoted Bacillus growth, increased bacterial diversity and lactic acid production and lowered pH to about 5. The importance of Cu²⁺, Zn²⁺, Fe²⁺ and I⁻ is different for Bacillus growth with the order Zn²⁺> Fe²⁺>Cu²⁺> I⁻ in a 21-d fermentation and Cu²⁺>I⁻>Fe²⁺>Zn²⁺ in a 42-d fermentation. Cu²⁺, Zn²⁺, Fe²⁺ and I⁻ is recommended at a level of 150, 60, 150 and 0.6 mg/kg respectively for the production of fermented liquid diet with Bacillus subtilis. The findings improve our understanding of the influence of trace elements on liquid diet fermentation with probiotics and support the proper use of trace elements in the production of fermented liquid diet for piglets.     

Effects of light quality,CO2 tensions and NO 3 +− concentrations on the inorganic nitrogen metabolism of Chlamydomonas reinhardii

The blue light dependent utilization of nitrate by green algae under common air and high irradiances, besides its assimilatory nature, is associated with the release of NO₂ ^– and NH₄ ⁺ to the culture medium. If the CO₂ content of the sparging air was increased up to 2%, previously excreted NO₂ ^– and NH₄ ⁺ were rapidly assimilated. When under air and high irradiances the cell density in the culture reached values corresponding to 25 g Ch 1.ml^-1, no further growth was observed and the highest values of NO₃ ^– consumption and NO₂ ^– and NH₄ ⁺ release were attained. Besides low CO₂ tensions, increasing NO₃ ^– concentrations in the medium stimulated the release of NO₃ ^– and NH₄ ⁺. Under CO₂-free air the consumption of NO₃ ^– and the release of NO₂ ^– and NH₄ ⁺ on a total N bases were almost stoichiometric and their rates saturated at much lower irradiances than under air. Under CO₂-free air high rates of NO₂ ^– release were only observed under the blue radiations that were effectively absorbed by photosynthetically active pigments, i.e. 460 nm, but not under 404 and 630 nm radiations. However, the simultaneous illumination of the cells with 404 and 630 nm monochromatic light showed a remarkable synergistic effect on NO₂ ^– release.The results are discussed in terms of the close relationship between C and N metabolism, the photosynthetic reducing power required to convert NO _inf3 ^sup± -N into R – NH₂-N and the blue light activation of nitrate reductase.     

Breakdown of self-incompatibility in a natural population of Petunia axillaris (Solanaceae) in Uruguay containing both self-incompatible and self-compatible plants

 Many members of the Solanaceae display a type of gametophytic self-incompatibility which is controlled by a single multiallelic locus, called the S-locus. From our previous survey of more than 100 natural populations of Petunia axillaris (a solanaceous species) in Uruguay, we had found that the majority of the populations of subspecies axillaris were comprised of virtually all self-incompatible individuals. The rest were ”mixed populations” which contained mostly self-incompatible and some self-compatible individuals. In this study, we examined the self-incompatibility behavior and determined the S-genotypes of 33 plants raised from seeds obtained from one such mixed population, designated U1. We found that 30 of the 33 plants (designated U1–1 through U1–33) were self-incompatible and a total of 18 different S-alleles were represented. To determine the S-genotypes of the three self-compatible plants (U1–2, U1–16, and U1–22) and the possible causes for the breakdown of their self-incompatibility, we carried out reciprocal crosses between each of them and each of the 18 S-homozygotes (S ₁ S ₁ through S ₁₈ S ₁₈ ) obtained from bud-selfed progeny of 14 of the 30 self-incompatible plants. For U1–2 and U1–16, we also carried out additional crosses with U1–25 (with S ₁ S ₁₃ genotype) and an S ₁₃ S ₁₅ plant (obtained from a cross between an S ₁₃ -homozygote and an S ₁₅ -homozygote), respectively. Based on all the pollination results and analysis of the production of S-RNases, products of S-alleles in the pistil, we determined the S-genotypes of U1–2, U1–16, and U1–22, and propose that the breakdown of self-incompatibility in these three plants is caused by suppression of the production of S₁₃-RNase from the S ₁₃ -allele they all carry. We have termed this phenomenon ”stylar-part suppression of an S-allele” or SPS. Received: 25 September 1998 / Revision accepted: 22 December 1998     

Influence of mixed antibiotics on Microcystis aeruginosa during the application of glyphosate and hydrogen peroxide algaecides

Antibiotics regulate various physiological functions in cyanobacteria and may interfere with the control of cyanobacterial blooms during the application of algaecides. In this study, Microcystis aeruginosa was exposed to H₂O₂ and glyphosate for 7 d in the presence of coexisting mixed antibiotics (amoxicillin, spiramycin, tetracycline, ciprofloxacin, and sulfamethoxazole) at an environmentally relevant concentration of 100 ng · L^?1. The mixed antibiotics significantly (P < 0.05) alleviated the growth inhibition effect of 15–45 μM H₂O₂ and 40–60 mg · L^?1 glyphosate. According to the increased contents of chlorophyll a and protein, decreased content of malondialdehyde, and decreased activities of superoxide dismutase and glutathione S‐transferase, antibiotics may reduce the toxicity of the two algaecides through the stimulation of photosynthesis and the reduction in oxidative stress. The presence of coexisting antibiotics stimulated the production and release of microcystins in the M. aeruginosa exposed to low concentrations of algaecides and posed an increased threat to aquatic environments. To eliminate the secondary pollution caused by microcystins, high algaecide doses that are ≥45 μM for H₂O₂ and ≥60 mg · L^?1 for glyphosate are recommended. This study provides insights into the ecological hazards of antibiotic contaminants and the best management practices for cyanobacterial removal under combined antibiotic pollution conditions.     

Genetic analysis of purple adenine (ad-3) mutants induced by methyl methanesulfonate in Neurospora crassa

The mutagenicity of methyl methanesulfonate (MMS) was studied in a genetically marked two-component heterokaryon of Neurospora crassa. Types of genetic alterations detectable in this system are (I) point mutations in the ad-3A and ad-3B loci; (2) multilocus (chromosome) deletions in the ad-3 region, and (3) recessive lethal mutations in the whole genome. Study of the inactivation kinetics of the heterokaryotic and homokaryotic conidial fractions has made it possible to distinguish between nuclear and cytoplasmic inactivation.Forward mutations in the ad-3 region induced by MMS in the heterokaryotic fraction of conidia were obtained by a direct method with the following results: (I) The overall ad-3 forward mutation frequency increases in proportion to the 1.91 power of the concentration of MMS. (2) The forward mutation frequency of point mutations at the ad-3A and ad-3B loci increases in proportion to the 1.68 power of the concentration. (3) The forward mutation frequency of chromosome deletions in the ad-3 region increases more than exponentially with increasing concentrations of MMS. (4) After treatment for 300 min with 20 mM MMS, 15.5% of the ad-3 mutations are multilocus deletions. Tests for genotype and allelic complementation of the point mutations showed that (I) the ratio between ad-3B and ad-3A mutants was 1.75, (2) 52.1% of the ad-3B mutants showed allelic complementation, with 39.2% non-polarized and 12.9% polarized complementation patterns and 47.9% noncomplementing mutants, and (3) both the ratio between point mutations in the ad-3A and ad-3B loci and the spectrum of complementation patterns among the ad-3B mutants were independent of MMS concentration.     

3种卫矛属植物叶片秋冬季转色期生理生化特征研究

以疏花卫矛(Euonymus laxiflorus)、丝棉木(E.maackii)和卫矛(E.alatus)3种卫矛属植物为试验材料,测定叶片转色期叶色参数和相关生理生化指标,探讨各项指标的变化规律和内在联系,为优良色叶植物的筛选提供依据。结果表明:(1)转色期,疏花卫矛的明亮度参数L~*和色素参数b~*(黄/蓝)呈上升趋势,色素参数a~*(红/绿)变化不大;丝棉木的L~*和b~*呈先上升后下降的单峰曲线,a~*呈上升趋势;卫矛的L~*和b~*变化不大,a~*呈上升趋势。(2)3种植物的叶绿素含量在转色期呈明显下降趋势;疏花卫矛的花色素苷相对含量、花色素苷/叶绿素的值较为平稳,类胡萝卜素/叶绿素的值呈上升趋势;丝棉木和卫矛的花色素苷相对含量、花色素苷/叶绿素的值均呈上升趋势,类胡萝卜素/叶绿素的值保持平稳。(3)3种植物苯丙氨酸解氨酶(PAL)活性呈下降趋势,查尔酮异构酶(CHI)活性呈先上升后下降的单峰曲线;卫矛的过氧化物酶(POD)和多酚氧化酶(PPO)活性保持平稳,疏花卫矛和丝棉木的POD活性呈上升趋势,疏花卫矛的PPO活性保持平稳,丝棉木的PPO活性呈下降趋势。(4)疏花卫矛和卫矛的可溶性糖和淀粉的质量分数呈先上升后下降的单峰曲线,丝棉木的可溶性糖和淀粉的质量分数呈上升趋势。(5)相关性分析显示,疏花卫矛呈现黄色主要是因为叶绿素的分解,丝棉木和卫矛呈现红色是因为花色素苷的合成,可溶性糖、淀粉、CHI对花色素苷的合成有一定作用,POD对叶片呈现红色有促进作用,PAL和PPO活性对花色素苷的合成无显著影响。     

Effects of magnolol and honokiol blend on performance,egg quality,hepatic lipid metabolism,and intestinal morphology of hens at late laying cycle

Magnolol and its isomer honokiol are polyphenols with anti-oxidative and anti-inflammatory activities. We evaluated the effects of magnolol and honokiol supplementation alone or in combination with hen diets during the late laying cycle. A total of 540 Jingfen pink-shell laying hens (50 weeks old) were randomly assigned to six treatments: a control diet and diets supplemented with 300 mg/kg magnolol (M₃₀₀), honokiol (H₃₀₀), or 300 mg/kg total phenols with a magnolol/honokiol ratio of 2:1 (M₂₀₀H₁₀₀), 1:2 (M₁₀₀H₂₀₀), and 1:1 (M₁₅₀H₁₅₀). Compared with that of the control, all supplementation groups had higher laying rates and the M₃₀₀, M₁₀₀H₂₀₀, and M₁₅₀H₁₅₀ groups showed comparatively lower feed conversion ratios. Magnolol and honokiol supplementation increased the Haugh units of fresh eggs at week 62 and alleviated the decline of the Haugh units of eggs stored for 14 days. Compared with that of the control group, the serum total antioxidant capacity of the M₁₀₀H₂₀₀ and M₁₅₀H₁₅₀ groups significantly increased, and all supplementation groups had higher total antioxidant capacity and lower malondialdehyde content in the liver. With respect to lipid metabolism, the M₂₀₀H₁₀₀ and M₁₅₀H₁₅₀ groups had lower total and relative liver weights compared with those of the control and H₃₀₀ groups. The mRNA expression levels of CCAAT enhancer binding protein alpha, sterol regulatory element binding protein-1, fatty acid synthase and stearyl coenzyme A desaturase 1 involved in lipogenesis; microsomal triglyceride transfer protein and apolipoprotein B involved in fatty acid transport; and the proinflammatory cytokine interleukin-1 beta were lower in all supplementation groups compared with those in the control. With respect to gut health, the heights of the jejunum and ileum villi significantly increased in all supplementation groups compared with those of the control, and the jejunum villus heights of the M₃₀₀ and M₁₅₀H₁₅₀ groups were higher than those of the H₃₀₀ and M₁₀₀H₂₀₀ groups. The H₃₀₀ and M₁₅₀H₁₅₀ groups had higher mRNA expression levels of zonula occludens-1 in the ileum compared with those in the control and M₃₀₀ groups, whereas all supplementation groups had higher mRNA levels of claudin-1 than that of the control group. In conclusion, magnolol and honokiol improved hen performance and the albumen quality of fresh and stored eggs by improving the antioxidant capacity, liver lipid metabolism, and intestinal health of laying hens. The combination of magnolol and honokiol at a 1:1 ratio may be an optimal choice for hen diet supplementation.     

白毫早茶园3种害虫与其捕食性天敌的数量、时间和空间关系

为了合理利用和保护天敌进行卵形短须螨、双斑长跗萤叶甲和假眼小绿叶蝉的综合防治,用灰色系统分析方法和生态位分析法对合肥地区白毫早茶园3种主要害虫与其捕食性天敌在数量、时间、空间等方面关系进行分析,利用害虫与天敌关系密切指数之和综合评判9种天敌与3种害虫关系密切的前四位天敌。2015年卵形短须螨的前四位天敌是鳞纹肖蛸(5.3079)、三突花蟹蛛(5.1716)、锥腹肖蛸(4.8367)和草间小黑蛛(4.7869);2016年前四位天敌依次是三突花蟹蛛(5.3975)、鳞纹肖蛸(4.9414)、茶色新圆蛛(4.8757)、锥腹肖蛸(4.6815)。对两年结果综合分析,卵形短须螨的前四位天敌依次是三突花蟹蛛(10.5691)、鳞纹肖蛸(10.2493)、茶色新圆蛛(9.6353)和锥腹肖蛸(9.5182)。2015年双斑长跗萤叶甲的前四位天敌依次是锥腹肖蛸(5.6926)、异色瓢虫(5.6976)、八斑球腹蛛(5.5101)和斜纹猫蛛(5.4552);2016年依次是茶色新圆蛛(5.2909)、锥腹肖蛸(5.2710)、鳞纹肖蛸(5.1063)和斜纹猫蛛(5.0703)。对两年结果综合评判,双斑长跗萤叶甲的前四位天敌是锥腹肖蛸(10.9636)、茶色新圆蛛(10.6578)、异色瓢虫(10.7580)和鳞纹肖蛸(10.5437)。2015年假眼小绿叶蝉的前四位天敌依次是锥腹肖蛸(5.3614)、粽管巢蛛(5.2259)、斜纹猫蛛(5.1300)和茶色新圆蛛(4.7472);2016年是锥腹肖蛸(5.2666)、粽管巢蛛(5.2561)、草间小黑蛛(4.9376)和斜纹猫蛛(4.8335)。对两年结果综合评判,假眼小绿叶蝉的前四位天敌依次是锥腹肖蛸(10.6280)、粽管巢蛛(10.4820)、斜纹猫蛛(9.9635)和茶色新圆蛛(8.6137)。该研究结果为白毫早茶园3种害虫防治时合理保护和利用自然界的天敌的种类提供了科学依据。     

Net release of dissolved organic matter by the scleractinian coral Acropora pulchra

The net production of dissolved organic matter (DOM) and dissolved combined and free amino acids (DCAA and DFAA, respectively) by the hermatypic coral Acropora pulchra was measured in the submerged condition, and the production rates were normalized to the coral surface area, tissue biomass, and net photosynthetic rates by zooxanthellae. When normalized to the unit surface area, the production rates of dissolved organic carbon and nitrogen (DOC and DON, respectively) were 37 and 4.4 nmol cm^− 2 h^− 1, respectively. Comparing with the photosynthetic rate by zooxanthellae, which was measured by ¹³C-tracer accumulation in the soft tissue of the coral colony, the release rate of DOC corresponded to 5.4% of the daily net photosynthetic production. The tissue biomass of the coral colony was 178 µmol C cm^− 2 and 23 µmol N cm^− 2, indicating that the release of DOC and DON accounted for 0.021% h^− 1 and 0.019% h^− 1 of the tissue C and N, respectively. The C:N ratios of the released DOM (average 8.4) were not significantly different from those of the soft tissue of the coral colonies (average 7.7). While DFAA did almost not accumulate in the incubated seawater, DCAA was considerably released by the coral colonies at the rate of 2.1 nmol cm^− 2 h^− 1 on average. Calculating C and N contents of the hydrolyzable DCAA, it was revealed that about 20% and 50%–60% of the released bulk DOC and DON, respectively, were composed of DCAA.     

Ionic Currents across the Plasmalemma of Chara inflata Cells: II. EFFECTS OF EXTERNAL Na+, Ca2+ AND Cl- ON K+ AND Cl CURRENTS

The electrical conductance of the plasmalemma of cells of Charainflata, due to the diffusion of ions, consists predominantlyof K⁺, Cl^– and leak components. When the membrane electricalpotential difference is stepped in a negative direction witha voltage-clamp, the resulting inward current has componentsI_K, I_Cl and I_L (leak). During such voltage-clamp steps I_K isinactivated, and Ic activated with voltage-dependent half-times.Increases in the external NaCl concentration reduce the magnitudeof I_K and increase the magnitude of I_c, but reduce the half-timeof inactivation or activation. The NaCl-induced changes in I_kand I_Cl and their kinetics were more pronounced at pH₀ =6.5than at pH₀ =9.5. When the concentration of external CaCl₂ wasincreased, I_k, I_Cl and the half-time of inactivation, (T_1/2),of I_k were all reduced. The half-time of activation of I_Cl wasincreased. The NaCI-induced changes could result from increases in bothexternal ion concentration and osmotic pressure. Previous experimentshave shown that an increase in external osmotic pressure alonealters the properties of the conductances. In this paper weattempt to separate the purely ionic effects from the osmoticones. Key words: Chara inflata, ionic effects, K⁺ and Cl^– currents     

Cyclic AMP phosphodiesterase activity in fetal and adult muscle of the rhesus monkey.

Total cyclic AMP phosphodiesterase activity of voluntary skeletal muscle of the rhesus monkey was highest in the 100-day fetal series, decreased near term, and was lowest in the adult series. Kinetic data indicated the existence of two cyclic AMP phosphodiesterase enzymes in both the fetal and adult muscle. The apparent K_m values for the high-affinity phosphodiesterase were similar in the 100-day fetal and adult skeletal muscle, whereas those for the low-affinity enzyme were twofold higher in the fetal series. The V_max of the high K_m enzyme was tenfold higher in the fetal than in the adult series and the low K_mV_max was fourfold higher in the fetal series. Both caffeine and theophylline were competitive inhibitors of the low K_m phosphodiesterase activity and noncompetitive inhibitors of the high K_m enzyme. No difference was observed in the sensitivity of the fetal and adult enzyme preparations to the methylxanthines or to Ro20-1724.