Sequence and evolution of rhesus monkey alphoid DNA

Summary Analysis of rhesus monkey alphoid DNA suggests that it arose by tandem duplication of an ancestral monomer unit followed by independent variation within two adjacent monomers (one becoming more divergent than the other) before their amplification as a dimer unit to produce tandem arrays. The rhesus monkey alphoid DNA is a tandemly repeated, 343-bp dimer; the consensus dimer is over 98% homologous to the alphoid dimers reported for baboon and bonnet monkey, 81% homologous to the African green monkey alpha monomer, and less than 70% homologous to the more divergent human alphoid DNAs. The consensus dimer consists of two wings (I and II, 172 and 171 bp, respectively) that are only 70% homologous to each other, but share seven regions of exact homology. These same regions are highly conserved among the consensus sequences of the other cercopithecid alphoid DNAs. The three alpha-protein binding sites reported for African green monkey alpha DNA by F. Strauss and A. Varshavsky (Cell 37: 889–901, 1984) occur in wings I and II, but with one site altered in wing I. Two cloned dimer segments are 98% homologous to the consensus, each containing 8 single-base-pair differences within the 343-bp segment. Surprisingly, 37% of these differences occur in regions that are evolutionarily conserved in the alphoid consensus sequences, including the alpha-protein binding sites. Sequence variation in this highly repetitive DNA family may produce unique nucleosomal architectures for different members of an alphoid array. These unique architectures may modulate the evolution of these repetitive DNAs and may produce unique centromeric characteristics in primate chromosomes.     

Structure, evolution, and tissue-specific synthesis of human apolipoprotein AIV

Apolipoprotein AIV (apoAIV) is a protein of the lipid transport system found associated with chylomicrons, high-density lipoprotein (HDL), and the lipoprotein-free fraction of the plasma. The gene coding for the human apoAIV is closely linked with the genes coding for apolipoproteins AI (apoAI) and CIII (apoCIII). In this paper a nearly full-length apoAIV cDNA clone has been isolated by screening an adult human liver DNA library using a human apoAIV gene probe. In-frame translation of the cDNA sequence in this clone indicated that the human apoAIV consists of 396 amino acid residues including a 20 residue long signal peptide. The coding region of this cDNA sequence contains 15 nucleotide repeats, 11 of which code for amino acid repeats with potentials of forming amphipathic helices. Alignment and comparison of the human and rat apoAIV amino acid sequences indicated a five-residue deletion near the carboxy terminus of the rat protein. This comparison also indicated that these proteins are 61.8% homologous, suggesting that the rate of evolution of apoAIV is 65 accepted point mutations (PAMs) per 100 residues per 100 million years. The rates of evolution of certain amino acid repeats in apoAIV are higher than the rate of evolution of the entire protein. However, the corresponding, computer-generated, secondary structures and hydropathy profiles of these repeats are very similar between the human and rat apoAIV. The relative steady-state levels of apoAIV mRNA in various human and monkey tissues were determined by hybridization blotting analysis of total RNA from these tissues using a human apoAIV cDNA probe.(ABSTRACT TRUNCATED AT 250 WORDS)     

猕猴神经干细胞的诱导分化、干性维持及同种脑内移植

为探索猕猴神经干细胞分化及特性维持,推进神经干细胞临床应用研究,该实验以绿色荧光蛋白(green fluorescence protein,GFP)为标记探讨猕猴胚胎干细胞向玫瑰花环(rosettes)结构神经干细胞的分化及其碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)和表皮生长因子(epidermal growth factor,EGF)的扩增培养。结果表明:1)建立了稳定高效的猕猴神经干细胞分化体系,在该分化体系下,GFP标记猕猴胚胎干细胞在分化的第12天时,95%以上的细胞分化为神经干细胞;2)分化得到的Rosettes结构神经干细胞经bFGF/EGF扩增后,能够较好地维持其Rosettes结构;3)经bFGF/EGF扩增后的rosettes结构神经干细胞移植到猕猴脑内后能够较好的存活并向神经元分化,即bFGF/EGF扩增培养能较好地维持Rosettes结构的神经干细胞,且移植到猕猴脑内的该细胞亦能够较好地存活并向神经元分化,该结果为神经干细胞应用于临床提供了基础理论依据。     

Rhesus monkey (Macaca mulatta) complex learning skills reassessed

Results from three experiments on basic learning and transfer in rhesus monkeys (Macaca mulatta) are reported in which fully automated testing paradigms, afforded by the Language Research Center's Computerized Test System (LRC-CTS), were employed. Performance levels for discrimination learning set, transfer index, and mediational-learning testing were uniformly higher than was predicted from the literature, in contrast to previous reports of compromised learning under similar conditions (automated apparatus, planimetric stimuli, spatial discontiguity between stimuli and response loci). Analyses reveal relatively advanced learning set performance, transfer-index ratios, and positive transfer of learning even at stringent criterion levels. Moreover, the data suggest that rhesus monkeys tested in these experiments exhibit mediational instead of associative learning strategies, as do great apes and in contrast to previous reports of rhesus learning. We argue that the LRC-CTS enhances learning by nonhuman primate subjects, obviating those factors, reported in the literature from experiments in which manual or other automated systems were employed, that compromise learning.     

A novel human apolipoprotein (apoM).

A novel human apolipoprotein designated apolipoprotein M (apoM) is described. The unique N-terminal amino acid sequence of apoM was found in an approximately 26-kDa protein present in a protein extract of triglyceride-rich lipoproteins (TGRLP). The isolated apoM cDNA (734 base pairs) encoded a 188-amino acid residue-long protein, distantly related to the lipocalin family. The mRNA of apoM was detected in the liver and kidney. Western blotting demonstrated apoM to be present in high density lipoprotein (HDL) and to a lesser extent in TGRLP and low density lipoproteins (LDL). The first 20 amino acid residues of apoM constituted a hydrophobic segment with characteristic features of a signal peptide. This was retained in the mature protein because of the lack of a signal peptidase cleavage site. In vitro translation in the presence of microsomes demonstrated translocation of apoM over the membrane and glycosylation but no signal peptide cleavage. The in vitro translated product remained associated with the microsomes after treatment with carbonate at pH 11, demonstrating that apoM is an integral protein. This finding suggests that apoM is linked to the single phospholipid layer of lipoproteins with a hydrophobic signal anchor. In conclusion, a novel human apolipoprotein, the function of which remains to be determined, is described.     

Denaturation of apolipoprotein A-I and the monomer form of apolipoprotein A-I(Milano).

In this study the thermal and denaturant induced unfolding of apolipoprotein A-I (apo A-I) and the monomer form of apolipoprotein A-I(Milano) (apo A-I(M)) was followed. Dimer apo A-I(M) was reduced with dithiothreitol, which was present in the protein solutions in all experiments. Thermal denaturation is followed by differential scanning calorimetry (DSC) and far-UV and near-UV CD. Both apo A-I and monomer apo A-IM have a broad asymmetric DSC peak that could be deconvoluted into three non two-state transitions, apo A-I being more stable than the monomer apo A-IM. Estimation of melting of tertiary structure by near-UV CD is lower than that for secondary structure determined from far-UV. This together with the non two-state unfolding of the proteins observed with DSC is indicative of unfolding via a molten globular-like state. Apo A-I and monomer apo A-I(M) are equally susceptible to guanidinum chloride, half-unfolded at 1.2 M denaturant. The presence of 0.5 and 1.0 M denaturant, lower and equalize the denaturation temperatures of the proteins, respectively.     

Multifocal candidiasis in a capuchin monkey (Cebus apella).

Candidiasis involving nasal, pharyngeal, and intestinal mucosal surfaces and a pharyngeal lymph node was demonstrated microscopically in a young adult female capuchin monkey (Cebus apella) experimentally infected with Schistosoma haematobium (Iran strain). Persistent nasal exudation and weight loss characterized the clinical disease preceding the animal's death.     

Complete Genome Sequence of Bartonella quintana,a Bacterium Isolated from Rhesus Macaques

Bartonella quintana is a re-emerging pathogen and the causative agent of a broad spectrum of disease manifestations in humans. The present study reports the complete genome of B. quintana strain RM_11, which was isolated from rhesus macaques.     

Pulmonary cestodiasis in a cynomolgus monkey (Macaca fascicularis).

Cestodiasis in primates has been noted historically to occur quite frequently, although tissue damage and clinical signs may or may not be apparent. Larval cestodes, such as hydatid cysts or cysticercus cysts, are known to cause extensive tissue damage, while other larval cestodes, such as tetrathyridia, cause minimal damage to the host. This case history concerns an apparently healthy cynomolgus monkey that was part of a surgical study. During the study, all parameters were normal. The monkey died 3 hours postsurgery. The apparent cause of death was respiratory arrest. At necropsy, it was discovered there were 1- to 3-mm-diameter cysts, which on transection extruded 2- to 5-mm-long larvae. The larvae could not be positively identified; however, they resembled tetrathyridia of Mesocestoides sp.     

Malignant lymphoma in a squirrel monkey (Saimiri sciureus).

A juvenile male Saimiri sciureus died of a tumor diagnosed as a histiocytic type of malignant lymphoma. The neoplasm presented as a thoracic mass occupying the posterior mediastinum and infiltrating the contiguous structures without involving distant nodes, the liver or spleen. The tumor tissue consisted of sheets or poorly defined clusters of fairly large cells with a vesicular nucleus and a variably abundant cytoplasm. The tumor cells were laid out in a poorly developed stroma of fine argyrophilic fibers. This is the first report of a spontaneous malignant lymphoma in a primate of this species. The speculation is put forth that the reported tumor is probably the first known example of the long sought after correlate of squirrel monkeys to Burkitt lymphoma in man.     

Persistent cloaca in a cynomolgus monkey (Macaca fascicularis).

A persistent cloaca was found to occur in a 15-year-old female cynomolgus monkey. This is the first case reported in a nonhuman primate. The embryological basis of this anomaly is discussed, and pertinent anatomical findings in this animal are reported which demonstrate the embryologic defect.     

Menetrier's disease in a rhesus monkey (Macaca mulatta).

Gross and microscopic features closely resembling those found in Menetrier's disease in man are described in a 20-month-old rhesus monkey. The gastric lining was characterized by greatly enlarged rugae caused by mucosal hypertrophy and hyperplasia along with outfolding of the muscularis mucosa and the submucosa. The mucosa and submucosa were infiltrated with inflammatory cells, mainly lymphocytes and plasma cells.     

Thyroid activity in a hypometabolic primate, the owl monkey (Aotus trivirgatus).

Serum levels of triiodothyronine (T3) and tetraiodothyronine (T4) were significantly lower in owl monkeys than in long-tailed macaques. These observations were considered to be consistent with the lower metabolic rate of the owl monkey. However, the absence of a significant difference in the levels of thyroid stimulating hormone (TSH) between the two species suggested a lower thyroid sensitivity to TSH in the owl monkeys. There was an inverse relation between levels of T3 and TSH in the owl monkeys at night and during the day.     

Structure, evolution, and regulation of chicken apolipoprotein A-I

A full-length cDNA clone for the precursor form of chicken liver apolipoprotein A-I (apoA-I) was isolated by antibody screening of a chicken liver cDNA library in the expression vector lambda gt11. The complete nucleotide sequence and predicted amino acid sequence of this clone is presented. The identity of the clone was confirmed by comparison with partial amino acid sequences for chicken apolipoprotein A-I. Chicken preproapolipoprotein A-1 consists of an 18-amino acid prepeptide, a 6-amino acid propeptide, and 240 amino acids of mature protein. The sequence of the protein is homologous to mammalian apoA-I and is highly internally repetitive, consisting largely of 11-amino acid repeats predicted to have an amphipathic alpha-helical structure. The sequence of the propeptide (Arg-Ser-Phe-Trp-Gln-His) differs in two positions from that of mammalian apoA-I. The mRNA for chicken apoA-I is about 1 kilobase in length and is expressed in a variety of tissues including liver, intestine, brain, adrenals, kidneys, heart, and muscle. This quantitative tissue distribution has been determined and is similar to that observed for mammalian apoE and different from that of mammalian apoA-I mRNA. This reinforces the concept that avian apoA-I performs functions analogous to those of mammalian apoE. Moreover, comparisons revealed sequences of chicken apoA-I similar to the region of mammalian apoE responsible for interaction with cellular receptors. Previous studies have demonstrated striking changes in the rates of synthesis of apoA-I in breast muscle during development and in optic nerve after retinal ablation. We now demonstrate that these changes are paralleled by changes in mRNA levels. ApoA-I mRNA levels increase approximately 50-fold in breast muscle between 14 days postconception and hatching and then decrease about 15-fold to adult levels. The levels of apoA-I mRNA increase about 3-fold in optic nerve following retinal ablation. ApoA-I mRNA is also found in the brain in the absence of nerve injury. This may indicate that locally synthesized apoA-I has a routine or housekeeping function in lipid metabolism in the central nervous system.