Reproductive activity of ruffed lemurs (Varecia variegata variegata) in a Madagascar rain forest

Mating activity was observed during four breeding seasons in two groups of black and white ruffed lemurs (Varecia variegata variegata) living in lowland rain forest on Nosy Mangabe island, Madagascar. The onset of the May-July breeding season was signalled by behavioral changes in adult males. Males made forays outside their usual home ranges, were more aggressive to other males, and performed appetitive and other sex-specific behaviors more frequently. Females showed receptive and proceptive behaviors during a 1-2 day behavioral estrus. Ruffed lemurs mated monogamously, polyandrously, and polygynously. These observations do not support previous assertions that they live only in monogamous families. Limited evidence suggests females exercised mate choice and may have preferred familiar males. © 1993 Wiley-Liss, Inc.     

Genetic control of retroviral disease in aging wild mice

Different populations of wild mice (Mus musculus domesticus) in Los Angeles and Ventura Counties were observed over their lifespan in captivity for expression of infectious murine leukemia virus (MuLV) and murine mammary tumor virus (MMTV) and for the occurrence of cancer and other diseases. In most populations of feral mice these indigenous retroviruses were infrequently expressed and cancer seldom occurred until later in life (>2 years old). MMTV was found in the milk of about 50% of wild mice, but was associated with only a low incidence (>1%) of breast cancer after one year of age. By contrast, in several populations, most notably at a squab farm near Lake Casitas (LC), infectious MuLV acquired at birth via milk was highly prevalent, and the infected mice were prone to leukemia and a lower motor neuron paralytic disease after one year of age. These two diseases were both caused by the same infectious (ecotropic)strain of MuLV and were the principal cause of premature death in these aging LC mice. A dominant gene called FV-4^R restricting the infection with ecotropic MuLV was found segregating in LC mice. Mice inheriting this FV-4^R allele were resistant to the ecotropic MuLV associated lymphoma and paralysis. The FV-4^R allele represents a defective endogenous MuLV provirus DNA segment that expresses an ecotropic MuLV envelope-related glycoprotein (gp70) on the cell surface. This FV-4^R encoded gp70 presumably occupies the receptor for ecotropic MuLV and blocks entry of the virus. The FV-4^R gene was probably acquired by the naturally occurring crossbreeding of LC feral mice with another species of feral mice (Mus castaneus) from Southeast Asia. The FV-4^R gp70 does not block entry of the amphotropic MuLV that uses a separate cell surface receptor. Therefore LC mice continued to be susceptible to the highly prevalent but weakly lymphogenic and nonparalytogenic amphotropic strain of MuLV. The study points out the potential of feral populations to reveal genes associated with specific disease resistance.     

Patterns of fluctuating asymmetry in sexual ornaments predict female choice

Extravagant secondary sexual characters are assumed to have arisen and be maintained by sexual selection. While traits like horns, antlers and spurs can be ascribed to intrasexual competition, other traits such as extravagant feather ornaments, displays and pheromones have to be ascribed to mate choice. A number of studies have tested whether females exert selection on the size of male ornaments, but only some of these have recorded female preferences for the most extravagantly ornamented males. Here I demonstrate that female choice can be directly predicted from the relationship between the degree of fluctuating asymmetry and the size of a secondary sexual character. Fluctuating asymmetry is an epigenetic measure of the ability of individuals to cope with stress, and it occurs when an individual is unable to undergo identical development of an otherwise bilaterally symmetric trait on both sides of its body. There is a negative relationship between the degree of fluctuating asymmetry and the absolute size of an ornament in those bird species with a female preference for the largest male sex trait, while there is a flat or U-shaped relationship among species without a female preference. These results suggest that females prefer exaggerated secondary sexual characters if they reliably demonstrate the ability of males to cope with genetic and environmental stress. Some species may demonstrate a flat or U-shaped relationship between the degree of fluctuating asymmetry and the absolute size of an ornament because (i) the genetic variance in viability signalled by the secondary sex trait has been depleted; (ii) the secondary sex trait is not particularly costly and therefore does not demonstrate condition dependence; or because (iii) the sex traits can be considered arbitrary traits rather than characters reflecting good genes.     

Nupr1 deficiency downregulates HtrA1, enhances SMAD1 signaling,and suppresses age-related bone loss in male mice

Nuclear protein 1 (NUPR1) is a stress-induced protein activated by various stresses, such as inflammation and oxidative stress. We previously reported that Nupr1 deficiency increased bone volume by enhancing bone formation in 11-week-old mice. Analysis of differentially expressed genes between wild-type (WT) and Nupr1-knockout (Nupr1-KO) osteocytes revealed that high temperature requirement A 1 (HTRA1), a serine protease implicated in osteogenesis and transforming growth factor-β signaling was markedly downregulated in Nupr1-KO osteocytes. Nupr1 deficiency also markedly reduced HtrA1 expression, but enhanced SMAD1 signaling in in vitro-cultured primary osteoblasts. In contrast, Nupr1 overexpression enhanced HtrA1 expression in osteoblasts, suggesting that Nupr1 regulates HtrA1 expression, thereby suppressing osteoblastogenesis. Since HtrA1 is also involved in cellular senescence and age-related diseases, we analyzed aging-related bone loss in Nupr1-KO mice. Significant spine trabecular bone loss was noted in WT male and female mice during 6−19 months of age, whereas aging-related trabecular bone loss was attenuated, especially in Nupr1-KO male mice. Moreover, cellular senescence-related markers were upregulated in the osteocytes of 6−19-month-old WT male mice but markedly downregulated in the osteocytes of 19-month-old Nupr1-KO male mice. Oxidative stress-induced cellular senescence stimulated Nupr1 and HtrA1 expression in in vitro-cultured primary osteoblasts, and Nupr1 overexpression enhanced p16^ink4a expression in osteoblasts. Finally, NUPR1 expression in osteocytes isolated from the bones of patients with osteoarthritis was correlated with age. Collectively, these results indicate that Nupr1 regulates HtrA1-mediated osteoblast differentiation and senescence. Our findings unveil a novel Nupr1/HtrA1 axis, which may play pivotal roles in bone formation and age-related bone loss.     

Depletion of Tip60/Kat5 affects the hepatic antioxidant system in mice

Tat-interactive protein 60 kDa (TIP60, also known as lysine acetyltransferase 5 [KAT5]) is a member of the MYST protein family with histone acetyltransferase activity. Recent studies have reported that TIP60 has multiple functions in many signal transduction mechanisms, especially p53-mediated apoptosis. Although the activation of apoptosis signaling pathways requires the presence of cellular reactive oxygen species (ROS) at a certain level, an imbalance between the production and consumption of ROS in cells results in oxidative stress (OS). In this study, we investigated for the first time how the absence of the Tip60 gene in the liver affects gene expression, enzyme activity, and protein expression of the hepatic antioxidant members localized in the cytoplasm, including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and glutathione S-transferase (GST). First, we successfully generated liver-specific Tip60 knockout mice (mutants) using Cre/LoxP recombination. The reduced glutathione level and nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) expression, a marker of OS, increased significantly in the Tip60 mutant liver. Gene expression, activity, and protein expression of the enzymatic antioxidant system, including SOD, CAT, GR, GPx, and GST were investigated in mutants and control groups. Despite a significant correlation between the gene, enzyme activity, and protein content for CAT and GR, this was not true for SOD and GPx. The overall results suggest that TIP60 acts on the hepatic antioxidant system both at the gene and protein levels, but the actual effect of the deletion of Tip60 is observed at the protein level, especially for SOD and GPx.     

Histological,Biochemical, and Ultrastructural Studies on Hyperpigmented Human Skin Xenografts

The mechanisms for hyperpigmentation observed in human cutaneous xenografts placed on athymic nude mice was investigated. Histologic, biochemical, histochemical, and ultrastructural examinations were performed on human skin prior to grafting and at various times ranging from 2 weeks to 30 weeks post-grafting (PG). Hyperpigmentation was macroscopically visible on the graft as early as 4–6 weeks. The number of Dopa-positive melanocytes per unit area was increased at 2 weeks PG and remained elevated until 20 weeks PG. The surface area of the melanocytes, a measure of the activity of the cells, also increased significantly and remained above the pre-grafting size throughout the study. Western blot analysis using tyrosinase specific antibody (αTy-SP) revealed the presence of tyrosinase exclusively in the grafted skin from 2 weeks to 12 weeks PG tested. Histological and ultrastructural observations revealed the presence of numerous dendritic melanocytes, indeterminant clear cells suggestive of Langerhans cells, and dermal melanophages. The results of this study suggest that the observed hyperpigmentation in grafted tissue is caused by an increase in the number of Dopa-positive melanocytes and probably from enhanced melanin production. Extracts of proteins from the xenografts exhibited prominent differences in low and high molecular proteins between pre- and post-grafted skin. Among them, the exclusive appearance of a protein doublet with apparent mw ～14 kDa was found in grafted skin, and subsequent studies indicate it has potent effects on melanocyte function.     

OSBPL3在代谢相关脂肪性肝病中的作用及机制研究

摘要 目的：探究氧化固醇结合蛋白类似物3（Oxysterol Binding Protein-like 3,OSBPL3）在代谢相关脂肪性肝病中的作用及可能机制。方法：建立肝脏特异性沉默OSBPL3小鼠模型和空载体对照组,分别予以普食和高脂喂养12周。分为正常对照组、OSBPL3沉默组、肥胖对照组、肥胖OSBPL3沉默组。观察小鼠一般情况,Real-time PCR检测脂质合成基因及脂质分解基因mRNA水平,western blot检测Akt/mTOR通路关键蛋白的表达。人HepG2细胞株给予不同浓度油酸（oleic acid,OA）处理,观察油红O染色的变化,western blot检测OSBPL3表达水平。结果：正常对照组与OSBPL3沉默组小鼠各项指标相比无统计学差异（P＞0.05）;与对照组相比,肥胖对照组及肥胖OSBPL3沉默组体质量、内脏脂肪及内脏脂肪指数较高（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组体质量、内脏脂肪及内脏脂肪指数较低（P＜0.05）。与对照组相比,肥胖对照组及肥胖OSBPL3沉默组总胆固醇(Total cholesterol,TC)、甘油三酯(triglycerides,TG)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)、低密度脂蛋白胆固醇(low density lipoprotein cholesterol,LDL-C)较高（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组TC、TG、LDL-C及HDL-C较低（P＜0.05）。与正常对照组与OSBPL3沉默组小鼠SREBP-1C、FAS及PPARα表达水平相比无统计学差异（P＞0.05）;与对照组相比,肥胖对照组及肥胖OSBPL3沉默组SREBP-1C、FAS较高,PPARα表达水平较低（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组SREBP-1C、FAS表达水平较低,PPARα表达水平较高（P＜0.05）。与对照组相比,肥胖对照组Akt及mTOR磷酸化表达水平较高（P＜0.05）;与肥胖对照组相比,肥胖OSBPL3沉默组Akt及mTOR磷酸化表达水平较低（P＜0.05）。随着OA作用浓度的升高,油红O染色逐渐加深。与0 μmol/L油酸相比,油酸以剂量依赖性方式增加HepG2细胞OSBPL3 mRNA水平（P<0.05）。结论：OSBPL3能够调控脂质代谢的表达,可能通过调控Akt/mTOR信号通路发挥生物学功能,有望为研究NAFLD疾病发生发展及治疗提供参考依据。     

Infectivity of preserved Cryptosporidium parvum oocysts for immunosuppressed adult mice

Abstract The present study was undertaken to determine the infectivity of Cryptosporidium parvum oocysts for immunosup-pressed adult C57BL/6N mice after the oocysts had been stored from 1–48 months at 4°C in 2.5% potassium dichromate. All mice inoculated with oocysts 1–18 months old developed patent infections, while mice inoculated with older oocysts remained uninfected. The prepatent period was extended from 2 to 6 or 7 days as the storage time for oocysts increased. The finding that C. parvum oocysts remain infective for mice for at least 18 months offers important economic and time-saving advantages for investigators who frequently require large numbers of oocysts that must be painstakingly purified from calf manure.