Effect of production conditions on the stability of a human bifidobacterial species Bifidobacterium longum in yogurt

Aims:  Human bifidobacteria are more sensitive to external environmental factors than animal bifidobacteria, and it is difficult to ensure their stable survival in yogurt. The purpose of this investigation was to observe the survival of human bifidobacteria in yogurts produced under various production conditions.
Methods:  Frozen or lyophilized bifidobacteria starters containing Bifidobacterium longum BB536 originally isolated from an infant, and commercial lyophilized yogurt starters were used for yogurt preparation. After producing yogurts under various conditions, the survival of bifidobacteria in these yogurts over various storage periods was observed.
Results:  Although there were some differences in bifidobacterial survival in yogurt between various production conditions, more than 1·0 × 10⁷ CFU g⁻¹ of Bif. longum survived in yogurt after 35 days' storage at 5°C. Lower fermentation temperature (37°C) and inclusion of Lactococcus lactis in the starter significantly ( P  < 0·05) improved survival of Bif. longum in the yogurt.
Conclusion:  In this investigation, the human bifidobacterial strain Bif. longum survived adequately in yogurt, although the fermentation temperature and starter composition affect bifidobacterial survival.
Significance and Impact of the Study:  This investigation indicates that stable probiotic yogurt using human bifidobacteria can be produced by choosing optimal production conditions.     

乳酸对大鼠大脑皮质神经元存活率的影响

目的:探讨乳酸对原代培养的皮质神经元存活率的影响.方法:体外原代培养大鼠大脑皮质神经元,将神经元分为两部分:①添加不同浓度乳酸(0,5,10,20 mmol/L)使培养液pH值分别降至7.35,7.15,6.95和6.00,观察神经元存活率;②添加不同浓度乳酸(0,5,10,20 mmol/L)后,保持培养液pH值为7.35,分别观察神经元存活率,分析乳酸对神经元的作用是通过下调pH值还是乳酸本身的作用.结果:①神经元存活率随pH降低而降低,与pH值为7.35组相比差异有显著性.②不同乳酸浓度对神经元存活率也有影响,神经元存活率降低,与对照组相比差异明显.③pH下调组神经元存活率显著低于相应乳酸作用组.结论:乳酸升高造成pH降低与神经元存活率关系密切,过量乳酸亦可不依赖下调pH值的作用发挥神经毒性.     

不同嫁接方法对印度枣成活率的影响

印度枣嫁接最适时期在每年4~6月份。低月龄小砧最适宜采用切接法;对2年生以上结果树,可采用短枝腹接法和芽接法进行品种更新换代。     

旅游对鸡形目鸟类巢成功率的影响——基于人工巢试验

旅游快速发展对野生动物的繁衍和种群发展造成的影响不容忽视。鸡形目鸟类大多为地面营巢,易受人为活动的影响。为揭示旅游对鸡形目鸟类巢成功率的影响,于2018年3—5月在河南董寨国家级自然保护区采用地面人工巢进行了两轮模拟试验,分析了试验轮次、巢密度、代表旅游活动强度的客流量和车流量,及植被类型、海拔等栖息地影响因子对人工巢成功率的影响。结果显示:客流量和海拔在繁殖成功巢和失败巢之间均存在不同程度的差异,繁殖成功巢的客流量较大、海拔较小,且在客流量较大、海拔较小的区域中人工巢的表观存活率明显较高。其中客流量是影响巢成功率的主导因素。此外,第二轮试验人工巢表观存活率显著低于第一轮试验,捕食者组成在不同试验轮次上也存在明显的差异,第一轮试验主要是鸟类,第二轮试验则是哺乳动物。白颈鸦、貉和野猪在本研究中是对巢威胁最大的捕食者。结果表明旅游活动可能会影响鸡形目鸟类的繁殖。因此建议在开展旅游活动时应综合考虑该区域所分布的野生动物及优先保护政策,注意控制旅游活动强度,以免对野生动物造成不良影响,并加强栖息地的保护。     

贮藏条件对川硬皮肿腿蜂存活率的影响

在相对湿度为50%~70%的条件下,设置5个温度梯度,将川硬皮肿腿蜂SclerodermasichuanensisXiao雌成蜂分别进行直接贮藏和定期补充15%蜂蜜水后贮藏,并对该蜂在不同条件下的贮藏存活率进行了比较。结果表明,贮藏温度和补充营养对川硬皮肿腿蜂雌成蜂的存活率有显著影响,其中6~15℃下贮藏相同时间的蜂存活率较高,比较适合该蜂的贮藏,而在12℃贮藏相同时间的供试蜂存活率最高,最适该蜂的贮藏。除此之外,在贮藏期间适时添加补充营养也能大大延长川硬皮肿腿蜂雌成蜂的贮藏寿命,但补充营养对该蜂存活率的影响大小与贮藏温度有关。     

五种不同苜蓿品种对苜蓿斑蚜实验种群存活率和生殖力的影响及抗性分析

苜蓿斑蚜Therioaphis trifolii(Monell)是危害苜蓿最为严重的害虫之一。通过室内饲养,选用5个不同的苜蓿品种,测定了不同苜蓿品种上苜蓿斑蚜存活率及生殖力的影响。结果表明:苜蓿斑蚜在不同苜蓿品种的世代平均存活率以固原紫花最高,达97.83%,阿尔冈金最低,为72.73%。以存活率和内禀增长率作为测定抗性的指标,供试品种对苜蓿斑蚜抗性的大小依次为德国大叶﹥阿尔冈金﹥宁苜1号﹥固原紫花﹥金皇后,与田间抗性鉴定结果基本相近。     

Effect of increased pCO2 in seawater on survival rate of different developmental stages of the harpacticoid copepod Tigriopus japonicus

The rapid increase in carbon dioxide levels in seawater is causing ocean acidification and is expected to have significant effects on marine life. To explore the ability of the harpacticoid copepod Tigriopus japonicus to adapt to an increased concentration of dissolved carbon dioxide (CO₂) in seawater, we compared the survival rates of adult and nauplius stages at 400, 1000, and 1550?ppm pCO₂ over a 14-day period. The survival rate of T. japonicus dramatically decreased over time with increase in pCO₂ concentration. At 1550?ppm, the survival rate showed a decrease of more than 20% at the end of the experimental period over that at 400?ppm. Furthermore, the survival rate decreased by a greater amount at all concentrations in nauplii than in adults, with a greater effect in wild-collected specimens than in culture-derived individuals. The results suggest that future ocean acidification may negatively influence the sustainability of T. japonicus and thus may eventually influence benthic ecosystems.     

电子束辐照对嗜虫书虱存活与繁殖力的影响

采用电子加速器产生电子束辐照处理嗜虫书虱Liposcelis entomophila(Enderlein),分别以0、50、100、200、300、400、500、1000Gy的剂量处理成虫和若虫,观察受辐照后的存活情况和成虫的繁殖情况;以0、25、50、100、200、300、400、500Gy的剂量辐照卵,观察受辐照后卵的孵化情况。结果表明:经50Gy及以上剂量辐照后嗜虫书虱的卵不能孵化,也不能存活;在300Gy及其以上剂量经过不到8周的时间后成虫和若虫都不能存活,且在300、400、500、1000Gy的剂量范围内,嗜虫书虱成虫和若虫受辐照后的剂量越大,存活率降低幅度越大。嗜虫书虱各虫态对电子束辐照的敏感性由高至低依次为卵、若虫、成虫;经300Gy辐照后的成虫和若虫分别在8周和6周内完全死亡,300Gy的剂量可作为电子束有效防治嗜虫书虱的参考剂量。所有50Gy以上剂量下都可明显降低此种害虫的繁殖力,300Gy以上剂量的处理可导致试虫零产卵。     

Influence of in vitro growth conditions on photosynthetic competence and survival rate of Rehmannia glutinosa plantlets during acclimatization period

The photosynthetic responses of Rehmannia glutinosa grown under photoautotrophic or heterotrophic conditions in vitro were investigated after transfer to greenhouse conditions. In addition, the changes in carbohydrate content and survival rates of the plantlets were evaluated. During six days after transplantation, the photosynthetic rate declined and photoinhibitory impairments represented by decrease of Fv/Fm and chlorophyll content were observed regardless of environmental conditions in vitro. Excessive transpiration was observed in plantlets grown under heterotrophic conditions during that period. Fructose and glucose content of the plantlets grown under photoautotrophic conditions increased with time and reached almost the same level of field grown plants after day 15. Under heterotrophic conditions, in contrast, the content of these sugars decreased continuously during that period. It is suggested that high survival rate of plantlets grown under photoautotrophic conditions has to be attributed to improvement of photosynthetic competence by imposed high light intensity and CO₂ concentration in vitro. The results strongly suggest that the control of transpiration during early stage after transplantation plays a key role in the acclimatization process, and photoautotrophic conditions could be a solution to solve the problems associated with transplantation stress. This revised version was published online in June 2006 with corrections to the Cover Date.     

碳酸盐碱度和pH值对凡纳滨对虾仔虾存活率的影响

采用静态急性毒理学方法,探讨了碳酸盐碱度和pH值对凡纳滨对虾(Litopenaeus vannamei)仔虾存活率的影响。结果表明:在pH值为7.5、8.0、8.5、9.0、9.5、10.0及10.5的试验组中,凡纳滨对虾仔虾存活率随着pH值的升高而下降,碳酸盐碱度在3mmol·L-1、pH值在9.0以上时,凡纳滨对虾仔虾的存活率受到影响显著;在碳酸盐碱度0～44.43mmol·L-1各试验组中,随着碳酸盐碱度升高,凡纳滨对虾仔虾的存活率下降,凡纳滨对虾仔虾对碳酸盐碱度的耐受性随着pH的升高明显下降;pH值为8.8时,碳酸盐碱度的48hLC50为36.81mmol·L-1,pH值为9.2时,碳酸盐碱度的48hLC50为33.05mmol·L-1,pH值为9.6时,碳酸盐碱度的48hLC50为5.55mmol·L-1;在本试验范围内,凡纳滨对虾对高碳酸盐碱度显示出较强的耐受性,是一种适宜移植到盐碱水域的养殖品种;碳酸盐碱度和pH对凡纳滨对虾的致毒作用是一个综合致毒效应,其中CO32-为主要致毒因子。     

广东松幼苗存活率和生长特征的初步研究

2006年5月至2008年7月,在南岭国家级自然保护区测定了不同年龄、不同种植方式的广东松(Pinus kwangtungensis)幼苗的存活率、株高和基径等指标,以期为国家保护植物广东松的保育提供资料。结果表明,实验期间袋栽苗存活率下降明显,从开始时的100%下降到结束时的50%;裸植苗与移植苗的存活率从100%下降到80%左右。总月均株高、基径的增量,袋栽苗、裸植苗、移植苗依次为1.01、1.39、2.76cm;0.17、0.20、0.64mm。年均株高、基径增值,移植苗、裸植苗、移植苗依次为32.91、17.22、12.77cm;7.64、2.31、2.0mm。随着年龄的增长,各组幼苗的株高和基径增长均加快,株高与基径之间存在着极显著的线性相关关系,广东松幼苗至10a生仍属快速生长期。     

苜蓿品种(系)对苜蓿斑蚜存活率和生殖力的影响

在田间抗蚜性鉴定的基础上,在室内25℃条件下,选用4个抗蚜性不同的苜蓿品种(系),测定了不同苜蓿品种(系)上苜蓿斑蚜Therioaphis maculate (Buckton)若虫存活率及生殖力的影响。结果表明: 苜蓿斑蚜在不同苜蓿品种（系）3、6叶期及成株期的存活率均以HA-3上最低,分别为8.00％±1.15％,21.27％±7.40％,17.07％±3.03％;Hu上最高,分别为25.63％±3.68％,42.27％±2.76％,55.10％±0.19％;且苗期显著低于成株期。以若虫存活率和内禀增长率作为测定抗生性的指标,供试品种(系)对苜蓿斑蚜抗生性的大小依次为HA-3>G3>JH>Hu,与田间抗性鉴定结果基本相近。     

东、黄海鳀鱼的胃排空率及其温度影响

在室内受控条件下,以卤虫幼体为饵料,测定了不同温度下鳀鱼的胃排空率,并比较了线性、指数和平方根3种常用数学模型对其排空曲线的拟合程度.统计结果表明,3种数学模型均可较好地描述鳀鱼的胃排空曲线 (df =10, r2=0.7820～0.9629, P<0.01),综合评价结果则进一步表明,指数模型最适于定量描述其胃排空曲线,平方根模型次之,直线模型较差.在研究温度范围内,鳀鱼的胃排空率随着温度的升高而加速增大,二者之间的定量关系可以用指数函数Rt=0.0354e0.0766T (R2=0.9770)加以定量描述.     

阿里山潜蝇茧蜂的羽化率及死亡率与储存温度的拟合关系

本文通过室内模拟低温,研究了阿里山潜蝇茧蜂雌成蜂、9日龄蛹的致死中温度和线性拟合。结果表明,在不同温度下雌蜂的砜分别为4℃下6．6149天,7℃下8．1235天,100℃下9．6161天,13℃下5．0257天,且在所有温度下都有死亡率陡升过程。9日龄蛹在不同温度下的LT50分别为4℃下8．4172天,7℃下8．1235天,10℃下13．9949天,13℃下18．4107天;同一温度下的蛹羽化率与保存天数的关系适宜用二次方程拟合。研究认为蛹的耐寒性强于雌成蜂,可以作为低温保存的虫态。     

Effect of cooling rate and equilibration time on pre-freeze and post-thaw survival of buck sperm

Survival of buck sperm is affected due to duration and temperature of stages of refrigerated or frozen storage. This study investigated interactive effect of cooling rates (moderate; MC and rapid cooling; RC); and equilibration times (0, 2, 4 and 8 h) on survival before freezing at 4 °C and post-thaw quality of buck sperm. Semen was collected (three Beetal bucks; replicates = 6), pooled and diluted with Tris-citrate extender. Pooled semen samples were subjected to either RC (−2.2 °C/min) or MC (−0.3 °C/min) from 37 °C to 4 °C in separate aliquots and further equilibrated at 4 °C for 8 h. Semen was frozen using standard procedure after completion of each equilibration period i.e. 0, 2, 4 and 8 h. Semen was evaluated for motility, viability, plasma membrane integrity (PMI) and normal apical ridge (NAR) before freezing and after thawing. The survival time (time for survival above threshold limit i.e. 60%) at 4 °C, of motility and PMI was observed 5 and 6 h respectively in RC group while >8 h in MC group. Rate of decline (slope) in motility and viability was higher (P < 0.05) in RC overtime during equilibration at 4 °C while PMI and NAR declined at equal rate in both cooling groups. Post-thaw motility and NAR were higher (P < 0.05) in MC when equilibrated for 2–8 h while viability and PMI of RC was observed equal to MC group. In conclusion, survival of buck sperm is higher when cooled with moderate rate. However, RC can maintain post-thaw sperm viability and PMI equal to MC when equilibrated for 2–8 h. The methods should be explored to maintain motility and NAR during rapid cooling of buck sperm.     

Effect of UVA fluence rate on indicators of oxidative stress in human dermal fibroblasts

During the course of a day human skin is exposed to solar UV radiation that fluctuates in fluence rate within the UVA (290-315 nm) and UVB (315-400 nm) spectrum. Variables affecting the fluence rate reaching skin cells include differences in UVA and UVB penetrating ability, presence or absence of sunscreens, atmospheric conditions, and season and geographical location where the exposure occurs. Our study determined the effect of UVA fluence rate in solar-simulated (SSR) and tanning-bed radiation (TBR) on four indicators of oxidative stress---protein oxidation, glutathione, heme oxygenase-1, and reactive oxygen species--in human dermal fibroblasts after receiving equivalent UVA and UVB doses. Our results show that the higher UVA fluence rate in TBR increases the level of all four indicators of oxidative stress. In sequential exposures when cells are exposed first to SSR, the lower UVA fluence rate in SSR induces a protective response that protects against oxidative stress following a second exposure to a higher UVA fluence rate. Our studies underscore the important role of UVA fluence rate in determining how human skin cells respond to a given dose of radiation containing both UVA and UVB radiation.     

Nest survival rate of Reeves's pheasant (Syrmaticus reevesii) based on artificial nest experiments

To explore the nest survival rate of Reeves's pheasant (Syrmaticus reevesii) and the nest-site factors that affect it,we conducted artificial nest experiments with reference to natural nests at Dongzhai National Nature Reserve (DNNR),Henan Province and Pingjingguan,Hubei Province from April to June 2014 simulating the situation in its early and later breeding season.We also determined distance characteristics of the nest sites by ArcGIS 10.0.Nest survival models were constructed in Program MARK for data analysis.Results indicated that in the early breeding season,the apparent survival rate (ASR) in DNNR (52.4％) was significantly greater than that in Pingjingguan (13.5％),and the ASR in the later breeding season in DNNR (26.7％) was not indistinctively correlated with Pingjingguan (3.2％).The daily survival rate (DSR) in the later breeding season was 93.8％ in DNNR and 92.0％ in Pingjingguan,respectively.The DSRs were both negatively correlated with nest distance to forest edges and settlements.The DSR in Pingjingguan was positively correlated with nest distance to paths and negatively correlated with nest distance to water sources.However,the DSR in DNNR was negatively correlated with nest distance to paths but positively correlated with nest distance to water sources.     

Effect of cooling rate on the survival of frozen wood frogs,Rana sylvatica

Summary Wood frogs (Rana sylvatica) were frozen to-2.5°C under five distinct cooling regimes to investigate the effect of cooling rate on survival. Frogs survived freezing when cooled at -0.16°C · h^-1 or -0.18°C · h^-1, but mortality resulted at higher rates (-0.30°C · h^-1,-1.03°C · h^-1, and -1.17°C · h^-1). Surviving frogs in the latter groups required longer periods to recover, and transient injury to the neuromuscular system was evident. Some of the frogs that died had patches of discolored, apparently necrotic skin; vascular damage, as indicated by hematoma, also occurred. It is concluded that slow cooling may be critical to the freeze tolerance of wood frogs. Additional studies examined the effect of cooling rate on physiological responses promoting freeze tolerance. Mean glucose concentrations measured in plasma (15–16 mol · ml^-1) and liver (42–45 mol · g^-1) following a 2-h thaw did not differ between slowly- and rapidly-cooled frogs but in both groups were elevated relative to unfrozen controls. Thus freezing injury to rapidly-cooled frogs apparently was not mitigated by the presence of elevated glucose. Water contents of liver tissue, measured 2 h post-thawing, did not differ between slowly-cooled (mean = 77.6%) and rapidly-cooled (mean = 78.5%) frogs. However, the mean hematocrit of slowly-cooled frogs (48%) was significantly higher than that (37%) of frogs cooled rapidly, possibly owing to differences in the dynamics of tissue water during freezing.