Evaluation of growth performance and lipid metabolism in zebrafish fed fructooligosaccharide using RNA sequencing

This study evaluated the effects of fructooligosaccharide (FOS) on growth performance and lipid metabolism in zebrafish (Danio rerio) by RNA sequencing. A total of 240 healthy zebrafish were randomly distributed into two groups. The control group was fed a basal diet, and the treatment group was fed a basal diet supplemented with 0.4% FOS. The results showed that there was no significant difference in growth performance (p > 0.05). The lipid content, total cholesterol, triglyceride, free fatty acid and low‐density lipoprotein were significantly lower (p < 0.05) in the liver of fish fed the 0.4% FOS diet than those of the fish fed the control diet, while the fish fed the 0.4% FOS diet had significantly higher (p < 0.05) high‐density lipoproteins than those of the control fish. Malic enzyme and fatty acid synthetase activities were significantly reduced by adding FOS. KEGG pathway analysis showed that the two pathways of steroid hormone biosynthesis and steroid biosynthesis were significantly enriched (p < 0.05). The profile of genes in these two pathways was affected by FOS in zebrafish. The results of the two pathways suggested new mechanisms underlying the lipid metabolism mechanism of FOS.     

Changes in brain and pituitary GnRH levels during ovarian maturation in wild female Japanese flounder

To elucidate the role of gonadotropin-releasing hormone (GnRH) in gonadal maturation in wild female Japanese flounder Paralichthys olivaceus, we monitored changes in the levels of seabream GnRH (sbGnRH) in the olfactory bulb, telencephalon, hypothalamus, and pituitary during ovarian development together with changes in plasma levels of testosterone (T), estradiol-17β (E₂), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). Fish were caught offshore of the northern mainland of Japan in the Pacific Ocean at 3- to 4-week intervals between April and September by gill net. The netted fish were categorized into six groups based on ovarian stages: previtellogenic (April–early May), early yolk (April–late May), late yolk (late May–June), early spawning (June–August), late spawning (September), and termination (September) stages. The gonadosomatic index significantly increased from the previtellogenic to early spawning stages and decreased thereafter. In the olfactory bulb, no significant differences were observed in sbGnRH levels among the developmental stages. In contrast, sbGnRH levels in the telencephalon and hypothalamus were very high in the previtellogenic stage, lower in the early spawning stage, and relatively high in latter stages. sbGnRH levels in the pituitary were high in the previtellogenic stage and low in the early spawning stage. In addition, the relatively high levels of pituitary sbGnRH were found together with high plasma T, E₂, and DHP levels in fish in the late yolk stage. These results indicate that sbGnRH in the telencephalon, hypothalamus, and pituitary is involved in ovarian maturation and that sbGnRH may play an important role in the initiation of ovarian recrudescence in wild Japanese flounder.     

大熊猫粪团表层和内部类固醇激素含量比较

大熊猫粪团表层和内部的类固醇激素含量是否存在显著差异,关系到取样量、取样精度及相似研究的可比性。通过测定5只大熊猫(3♀2♂)粪团表层和内部类固醇激素(雌二醇、睾酮、皮质醇)含量并对其进行相关性分析,结果表明:大熊猫粪团雌二醇、睾酮、皮质醇在粪团表层和内部的含量均存在显著差异,并呈显著正相关。     

Effects of acute and chronic zinc exposure on steroid hormone receptor expression in the lined seahorse,Hippocampus erectus

The element zinc (Zn) can elicit a variety of physiological responses in animals, particularly through its effects on steroid hormone receptor expression. Here, we evaluated the effects of Zn on the expression profiles of steroid hormone receptors in the lined seahorse, Hippocampus erectus, following experimental acute and chronic Zn exposure. Complex response patterns were observed; however, steroid hormone receptor expression in liver and kidney following 12‐day Zn injection (acute exposure) differed significantly from the control treatments. Apparent effects on hepatic lipid metabolism and osmotic regulation in the kidney need detailed investigation. Furthermore, 49‐day (chronic) waterborne Zn exposure produced a significant decrease in both estrogen receptor (ER) expression levels and estradiol concentrations. In additional, chronic exposure led to a substantial reduction of hepatic adipose cells, implying that Zn may regulate hepatic lipid metabolism via ER and estradiol. Our study demonstrated the effects of both acute and chronic Zn exposure on expression patterns of steroid hormone receptors, which will contribute to understanding the mechanism of Zn‐induced hepatic lipid metabolism and other physiological responses in seahorses.     

苦马豆素抑制N-聚糖加工对生殖激素分泌功能的影响

苦马豆素（SW）中毒可引起生殖激素分泌紊乱,其中,促性腺激素是糖蛋白,由N-聚糖糖基化修饰调控其活性和功能。SW是N-聚糖加工过程中ɑ-甘露糖苷酶的抑制剂,而SW如何通过改变N-聚糖加工过程进一步影响生殖激素的分泌功能尚不明确。因此,本试验建立SW染毒妊娠期小鼠模型,利用MALDI-TOF-MS质谱法检测糖蛋白N-聚糖糖链结构的变化,分析N-聚糖加工过程中糖基酶的活性和生殖激素水平及其受体蛋白表达量。随着SW染毒时间的延长,染毒组小鼠垂体前叶糖蛋白的5种复合型N-聚糖糖链结构消失,而新增加3种杂合型N-聚糖糖链结构;N-聚糖糖基转移酶和糖苷酶的活性均显著下降;进一步发现染毒组小鼠卵巢促性腺激素受体、雌二醇和孕酮受体蛋白表达量显著低于对照组,并且生殖激素分泌水平也出现显著下降。SW可显著抑制N-聚糖糖基酶的活性使糖蛋白上N-聚糖糖链结构发生改变,影响促性腺激素及其受体的活性,使其对下游类固醇激素分泌的调控作用失衡,最终导致小鼠妊娠期生殖激素分泌紊乱。     

泰山螭霖鱼卵巢年周期中卵母细胞发育及其性腺类固醇激素作用

【目的】研究泰山螭霖鱼(Varicorhinus macrolepis)卵巢和卵母细胞在年周期中的发育变化规律，以及性激素在卵母细胞发育中的调控作用；【方法】利用解剖学、组织学、组织化学以及放射免疫的方法对泰山螭霖鱼卵巢和卵母细胞的解剖学、组织学、组织化学以及性激素水平在年周期中的变化规律进行了研究。【结果】2～4月份，卵巢由Ⅳ期发育至第v期，4月份进入繁殖期；4～6月份，为第v期；6月下旬～7月份为第vi期，是排卵后退化阶段；8月份，为Ⅱ期卵巢（休整期）；9月份～翌年的1月份为第Ⅲ期，以Ⅲ期卵巢过冬。泰山螭霖鱼血清17β-雌二醇(E2)自1月份开始升高，排卵前即3月份达到高峰（53.6 pg·ml-1左右），4月份排卵时降为20.22 pg·ml-1，一直持续到9月份，降至最低点，1.6667 pg·ml-1左右，之后维持在低水平，到1月份又开始上升。血清17α，20β－双羟孕酮（17α，20β-DHP）在4月份（接近排卵时）达到高峰，56.333 pg·ml-1，然后维持高水平（56.333～50.667 pg·ml-1）至排卵结束（6月份），11月份～翌年3月份均维持低水平（35～15 pg·ml-1）；【结论】泰山螭霖鱼为短期分批产卵类型，一年一个产卵期，E2和17α，20β-DHP对卵母细胞发育有重要的调控作用。     

Effects of low ph exposure of adult salmonids on gametogenesis and embryo development

Mature male and female rainbow trout were treated with low pH (Av. 4.5) sulfuric acid water for 1 or 2 weeks. Percentage of eyed embryos in eggs from control, 1-week-treated and 2-week-treated females were 100%, 80% and 0%, respectively. Low pH exposure of male trout induced 11% deformation in embryos fertilized with their sperm. In order to clarify the physiological mechanism of the effects of low pH exposure, sex hormone levels were compared. In female fish, plasma sex hormones levels showed no difference among the groups, but egg contents of 1720-dihydroxy-4-pregnen-3-one, which induces oocyte maturation, were significantly lower in low pH exposed groups. Acidified male fish showed higher plasma levels of the spermiation inducing hormone, 11-ketotestosterone. Effects on eggs were manifested under pH lower than 5. Under continual rearing of land-locked sockeye salmon in acid water, the effects on the oocyte were observed in those adult females which were exposed to acidic condition for more than 1 week before the timing of ovulation. These results suggest that low pH affects oocyte maturational events occurring just 1 week before ovulation, and that acid stress affects the endocrinological mechanisms of final maturation in fish gametocytes. Thus, acidification of the aquatic environment may reduce the reproductive activity of fish at rather low acidity levels.     

表皮生长因子对胎鼠卵巢卵泡体外发育和类固醇激素分泌的影响

表皮生长因子（EGF）是参与卵巢功能调节的一个重要肽类因子，关于EGF对小鼠胚胎期卵巢卵泡发育和类固醇激素发育的 今未见报道。本研究以单个卵巢的放泡数、生长卵泡数和5个最大卵母 平均直径为卵泡发育优劣的衡量指标，利用我们早期研究建立的无血清培养体系研究了EGF对胎鼠卵巢卵泡发育和类固醇激素分泌的作用。结果发现：①EGF处理组胎鼠卵巢总卵泡数、生长卵九和卵巢内5个最大卵母细胞平均直径从培养第7天起即显著高于ITS对照组直至培养结束；②EGF在培养后期显著促进胎鼠卵巢分泌睾酮，但对雌二醇的基础分泌无影响；③EGF处理组胎鼠卵巢在培养过程的后期引起贴壁的卵巢边缘脱离培养板底壁发生卷边现象，丧失卵母细胞皮持－髓质生长模式。结果提示：EGF在胎鼠卵巢原始卵泡生长起始中起重要作用， 同时EGF促进胎鼠卵巢小腔前卵泡／卵母细胞进一步生长、发育和体外存活；EGF促卵泡发作用与雌二醇的作用无关。