Identification and functional analysis of an ovarian form of the egg activation factor phospholipase C zeta (PLCζ) in pufferfish

Recent studies suggest that egg activation in mammals is triggered by a sperm-specific phospholipase C, PLCzeta. In other vertebrate species such as medaka fish, chickens, and quail, PLCzeta is also expressed as a testis-specific mRNA. Functional studies suggest that PLCzeta plays a similar role as a trigger of egg activation in these species. Here, we report the identification of PLCzeta orthologues in pufferfish species Takifugu rubripes (Fugu) and Tetraodon nigroviridis (Tetraodon). Unexpectedly in these species PLCzeta is expressed not in the testis, but in ovary and brain. Injection of pufferfish PLCzeta copy ribonucleic acid (cRNA) into mouse eggs failed to trigger calcium oscillations, unlike medaka PLCzeta cRNA. Our findings provide the first evidence that PLCzeta may be expressed in the egg, rather than the sperm, in some vertebrate species, and that its mechanism of action and physiologic role at fertilization may differ in different vertebrate species.     

Maternal inheritance of plastids and mitochondria in Cycas L. (Cycadaceae)

Cycas is often considered a living fossil, thereby providing a unique model for revealing the evolution of spermatophytes. To date, the genetic inheritance of these archaic plants is not fully understood. The present study seeks to document the process of organelle inheritance in an interspecific cross of Cycas species. Extranuclear organelle DNA from chloroplasts and mitochondria was analyzed using both polymerase chain reaction-restriction fragment length polymorphism analysis and microscopy. Here, we show that the chloroplasts and mitochondria in the progeny of interspecific crosses between Cycas taitungensis and Cycas ferruginea were exclusively inherited from the female parent. Epifluorescence microscopic analyses of the pollen cells from Cycas elongata indicated that there was a significant degradation of organelle DNA in male reproductive cells following maturation; the DNA fluorescent signals were only seen after pollen mitosis two, but not detectable at mature stage. Lack of organelle DNA fluorescent signal in prothallial cells was confirmed by the absence of plastids and mitochondria in electronic microscopic images. In conclusion, these data suggest that the maternal plastid and mitochondrial inheritance in Cycas, native to the old world, are the same as seen in seed plants.     

miR-21 targets the tumor suppressor RhoB and regulates proliferation, invasion and apoptosis in colorectal cancer cells

It has become increasingly clear that microRNAs play an important role in many human diseases including cancer. Here, we show that expression of miR-21 in HEK293 and several colorectal cancer cells was found inversely correlated with ras homolog gene family, member B (RhoB) expression. miR-21 expression significantly suppressed RhoB 3' UTR luciferase-reporter activity, but the inhibitory effect was lost when the putative target sites were mutated. Exogenous miR-21 over-expression mimicked the effect of RhoB knockdown in promoting proliferation and invasion and inhibiting apoptosis, whereas anti-miR-21 or RhoB expression yielded opposite effects, in colorectal cancer cells. These results suggest that miR-21 is a regulator of RhoB expression and RhoB could be a useful target in exploring the potential therapeutic benefits of miR-21 mediated tumor cell behaviors in colorectal cancer.     

A new xanthene‐based two‐photon fluorescent probe for the imaging of 1,4‐dithiothreitol (DTT) in living cells

1,4‐Dithiothreitol (DTT) has wide applications in cell biology and biochemistry. Development of effective methods for monitoring DTT in biological systems is important for the safe handling and study of toxicity to humans. Herein, we describe a two‐photon fluorescence probe (Rh‐DTT) to detect DTT in living systems for the first time. Rh‐DTT showed high selectivity and sensitivity to DTT. Rh‐DTT can be successfully used for the two‐photon imaging of DTT in living cells, and also can detect DTT in living tissues and mice.     

A novel tomato F‐box protein,SlEBF3, is involved in tuning ethylene signaling during plant development and climacteric fruit ripening

Ethylene is instrumental to climacteric fruit ripening and EIN3 BINDING F‐BOX (EBF) proteins have been assigned a central role in mediating ethylene responses by regulating EIN3/EIL degradation in Arabidopsis. However, the role and mode of action of tomato EBFs in ethylene‐dependent processes like fruit ripening remains unclear. Two novel EBF genes, SlEBF3 and SlEBF4, were identified in the tomato genome, and SlEBF3 displayed a ripening‐associated expression pattern suggesting its potential involvement in controlling ethylene response during fruit ripening. SlEBF3 downregulated tomato lines failed to show obvious ripening‐related phenotypes likely due to functional redundancy among SlEBF family members. By contrast, SlEBF3 overexpression lines exhibited pleiotropic ethylene‐related alterations, including inhibition of fruit ripening, attenuated triple‐response and delayed petal abscission. Yeast‐two‐hybrid system and bimolecular fluorescence complementation approaches indicated that SlEBF3 interacts with all known tomato SlEIL proteins and, consistently, total SlEIL protein levels were decreased in SlEBF3 overexpression fruits, supporting the idea that the reduced ethylene sensitivity and defects in fruit ripening are due to the SlEBF3‐mediated degradation of EIL proteins. Moreover, SlEBF3 expression is regulated by EIL1 via a feedback loop, which supposes its role in tuning ethylene signaling and responses. Overall, the study reveals the role of a novel EBF tomato gene in climacteric ripening, thus providing a new target for modulating fleshy fruit ripening.     

Parabacteroides distasonis Alleviates Obesity and Metabolic Dysfunctions via Production of Succinate and Secondary Bile Acids

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贵州北盘江喀斯特地区车桑子造林对乡土植物物种多样性的影响

为明确车桑子(Dodonaea viscosa)造林对北盘江喀斯特地区乡土植物物种多样性的影响,该研究采用群落样地调查法对不同车桑子覆盖度(0、20%、40%、60%、80%、100%)下的植物群落进行实地调查,并对其植物群落的物种多样性进行了对比分析。结果表明:(1)随车桑子覆盖度的增加,群落物种数及高位芽物种数有所下降,留下的物种多为地面芽、隐芽和一年生的草本植物。(2)随车桑子覆盖度的增加,Margalef指数、Simpson指数、Shan-non-Wiener指数及Pielou指数均呈下降趋势,群落中植物的种类和数量均减少,群落结构趋于简单,稳定性降低。(3)随车桑子覆盖度的增加,群落的物种组成不断发生替换,且草本植物的物种替代率均大于木本植物,但群落中物种间替代率呈先降低后升高的趋势,相邻两覆盖度之间的物种相似性系数呈先增加后减小的趋势。研究认为,当车桑子覆盖度≥60%后,乡土植物物种丰富度、多样性相对较低,物种分配不均匀,群落结构变简单,稳定性较差,不利于群落向更高级的演替阶段发展。     

Effects on Liver Hydrogen Peroxide Metabolism Induced by Dietary Selenium Deficiency or Excess in Chickens

To determine the relationship between dietary selenium (Se) deficiency or excess and liver hydrogen peroxide (H₂O₂) metabolism in chickens, 1-day-old chickens received insufficient Se (0.028 mg Se per kg of diet) or excess Se (3.0 or 5.0 mg Se per kg of diet) in their diets for 8 weeks. Body and liver weight changes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, H₂O₂ content, and activities and mRNA levels of enzymes associated with H₂O₂ metabolism (catalase (CAT) and superoxide dismutase (SOD) 1–3) were determined in the liver. This study showed that Se deficiency or excess Se intake elicited relative severe changes. Se deficiency decreased growth, while Se excess promoted growth in chickens. Both diets vastly altered the liver function, but no obvious histopathological changes were observed in the liver. Se deficiency significantly lowered SOD and CAT activities, and the H₂O₂ content in the liver and serum increased. Se excess (3.0 mg/kg) decreased SOD and CAT activities with changes in their mRNA levels, and the H₂O₂ content increased. The larger Se excess (5.0 mg/kg) showed more serious effects but was not fatal. These results indicated that the H₂O₂ metabolism played a destructive role in the changes in bird liver function induced by Se deficiency or excess.