Semen collection by urethral catheterization and electro-ejaculation with different voltages, and the effect of holding temperature and cooling rate before cryopreservation on semen quality in the Japanese macaque (Macaca fuscata)

In the Japanese macaque, semen has been collected by electro-ejaculation (EE), using the higher voltage stimuli compared to other species including genus Macaca. Semen coagulate immediately after ejaculation, which makes difficult to produce high-quality semen for artificial insemination. Recently, semen collection using urethral catheterization (UC) has been reported in carnivore and this technique may allow semen collection without coagulation in a less invasive manner. Further, the temporal preservation temperature and cooling rate of semen during cryopreservation affect post thawing sperm quality. In this study, to improve semen quality and quantity, as well as the animal welfare, semen collection was performed by EE with high (5-15 V) or low (3-6 V) voltage, UC and a combination of the two (EE-UC). It has been suggested that a high voltage is necessary for semen collection, but 10 V stimulation was effective enough and 15 V is for additional sperm collection. Also, liquid semen was collected by EE-UC and this could increase the total number of sperm. Further, to improve the post thawing sperm motility, semen was kept at four temperatures (4, 15, 25 and 37˚C) for 60 min, and processed with two cooling procedures (slow cooling before second dilution and fast cooling after second dilution). Holding semen at 25˚C and fast cooling after the second dilution maintained progressive motile sperm rate. The present results will contribute to the improvement of semen collection and animal welfare of Japanese macaques.

Structural variations of subterminal satellite blocks and their source mechanisms as inferred from the meiotic configurations of chimpanzee chromosome termini

African great apes have large constitutive heterochromatin (C-band) blocks in subtelomeric regions of the majority of their chromosomes, but humans lack these. Additionally, the chimpanzee meiotic cell division process demonstrates unique partial terminal associations in the first meiotic prophase (pachytene). These are likely formed as a result of interaction among subtelomeric C-band blocks. We thus conducted an extensive study to define the features in the subtelomeric heterochromatic regions of chimpanzee chromosomes undergoing mitotic metaphase and meiotic cell division. Molecular cytogenetic analyses with probes of both subterminal satellite DNA (a main component of C-band) and rDNA demonstrated principles of interaction among DNA arrays. The results suggest that homologous and ectopic recombination through persistent subtelomeric associations (post-bouquet association observed in 32% of spermatocytes in the pachytene stage) appears to create variability in heterochromatin patterns and simultaneously restrain subtelomeric genome polymorphisms. That is, the meeting of non-homologous chromosome termini sets the stage for ectopic pairing which, in turn, is the mechanism for generating variability and genomic dispersion of subtelomeric C-band blocks through a system of concerted evolution. Comparison between the present study and previous reports indicated that the chromosomal distribution rate of sutelomeric regions seems to have antagonistic correlation with arm numbers holding subterminal satellite blocks in humans, chimpanzees, and gorillas. That is, the increase of subterminal satellite blocks probably reduces genomic diversity in the subtelomeric regions. The acquisition vs. loss of the subtelomeric C-band blocks is postulated as the underlying engine of this chromosomal differentiation yielded by meiotic chromosomal interaction.

Considerable Synteny and Sequence Similarity of Primate Chromosomal Region VIIq31

Human chromosome 7 has been the focus of many behavioral, genetic, and medical studies because it carries genes related to cancer and neurodevelopment. We examined the evolution of the chromosome 7 homologs, and the 7q31 region in particular, using chromosome painting analyses and 3 paint probes derived from (i) the whole of chimpanzee chromosome VII (wcVII), (ii) human 7q31 (h7q31), and (iii) the chimpanzee homolog VIIq31 (cVIIq31). The wcVII probe was used instead of the whole human chromosome 7 because the chimpanzee contains additional C-bands and revealed large areas of synteny conservation as well as fragmentation across 20 primate species. Analyses focusing specifically on the 7q31 homolog and vicinity revealed considerable conservation across lineages with 2 exceptions. First, the probes verified an insertion of repetitive sequence at VIIq22 in chimpanzees and bonobos and also detected the sequence in most subtelomeres of the African apes. Second, a paracentric inversion with a breakpoint in the cVIIq31 block was found in the common marmoset, confirming earlier studies. Subsequent in silico comparative genome analysis of 17 primate species revealed that VIIq31.1 is more significantly conserved at the sequence level than other regions of chromosome VII, which indicates that its components are likely responsible for critical shared traits across the order, including conditions necessary for proper human development and wellbeing.

Evolutionary Origin of OwlRep, a Megasatellite DNA Associated with Adaptation of Owl Monkeys to Nocturnal Lifestyle

Rod cells of many nocturnal mammals have a “non-standard” nuclear architecture, which is called the inverted nuclear architecture. Heterochromatin localizes to the central region of the nucleus. This leads to an efficient light transmission to the outer segments of photoreceptors. Rod cells of diurnal mammals have the conventional nuclear architecture. Owl monkeys (genus Aotus) are the only taxon of simian primates that has a nocturnal or cathemeral lifestyle, and this adaptation is widely thought to be secondary. Their rod cells were shown to exhibit an intermediate chromatin distribution: a spherical heterochromatin block was found in the central region of the nucleus although it was less complete than that of typical nocturnal mammals. We recently demonstrated that the primary DNA component of this heterochromatin block was OwlRep, a megasatellite DNA consisting of 187-bp-long repeat units. However, the origin of OwlRep was not known. Here we show that OwlRep was derived from HSAT6, a simple repeat sequence found in the centromere regions of human chromosomes. HSAT6 occurs widely in primates, suggesting that it was already present in the last common ancestor of extant primates. Notably, Strepsirrhini and Tarsiformes apparently carry a single HSAT6 copy, whereas many species of Simiiformes contain multiple copies. Comparison of nucleotide sequences of these copies revealed the entire process of the OwlRep formation. HSAT6, with or without flanking sequences, was segmentally duplicated in New World monkeys. Then, in the owl monkey linage after its divergence from other New World monkeys, a copy of HSAT6 was tandemly amplified, eventually forming a megasatellite DNA.

Derivation of induced pluripotent stem cells in Japanese macaque (Macaca fuscata)

Non-human primates are our closest relatives and are of special interest for ecological, evolutionary and biomedical research. The Japanese macaque (Macaca fuscata) has contributed to the progress of primatology and neurosciences over 60 years. Despite this importance, the molecular and cellular basis of the Japanese macaque remains unexplored since useful cellular tools are lacking. Here we generated induced pluripotent stem cells (iPSCs) from skin fibroblasts of the Japanese macaque with Sendai virus or plasmid vectors. The Japanese macaque iPSCs (jm-iPSCs) were established under feeder-free culture conditions, but feeder cells turned out to be essential for their maintenance. The jm-iPSCs formed human iPSC-like flat colonies which were positive for pluripotent antigens including alkaline phosphatase, SSEA4, and TRA-1-81. They also expressed endogenous OCT3/4, SOX2, L-MYC, and KLF4 and other pluripotent marker genes. The potential to differentiate into all three germ layers and neural stem cells was confirmed by embryoid body and neurosphere formation, respectively. The jm-iPSCs will provide a robust in vitro tool for investigating the underlying mechanisms of development and physiology studies with the Japanese macaque.

A prospective phase II study of combined androgen blockade in patients with androgen receptor-positive metastatic or locally advanced unresectable salivary gland carcinoma

Background

There is no standard first-line chemotherapy for recurrent/metastatic (RM) or unresectable locally advanced (LA) salivary gland carcinoma (SGC).

Patients and methods

We conducted a single institution, open-label, single arm, phase II trial of combined androgen blockade (CAB) for androgen receptor (AR)-positive SGC. Leuprorelin acetate was administered subcutaneously at a dose of 3.75 mg every 4 weeks. Bicalutamide was administered orally at a daily dose of 80 mg. Patients were treated until progressive disease or unacceptable toxicities.

Results

Thirty-six eligible patients were enrolled. Thirty-three patients had RM disease and three patients had LA disease. The pathological diagnoses were salivary duct carcinoma (34 patients, 94%) and adenocarcinoma, NOS (two patients, 6%). The best overall response rate was 41.7% [n = 15, 95% confidence interval (CI), 25.5%-59.2%], the clinical benefit rate was 75.0% (n = 27, 95% CI, 57.8%-87.9%). The median progression-free survival was 8.8 months (95% CI, 6.3-12.3 months) and the median overall survival was 30.5 months (95% CI, 16.8 months to not reached). Additional analyses between treatment outcomes and clinicopathological factors or biomarkers including AR positivity, human epidermal growth factor receptor 2 status, and its complex downstream signaling pathway gene mutations showed no statistically significant differences. Elevated grade 3 liver transaminases and increased serum creatinine were reported in two patients, respectively. Discontinuation of leuprorelin acetate or bicalutamide due to adverse event occurred in one patient.

Conclusion

This study suggests that CAB has equivalent efficacy and less toxicity for patients with AR-positive RM or unresectable LA SGC compared with conventional chemotherapy, which warrants further study.

Clinical Trial Registration

UMIN-CTR (http://www.umin.ac.jp/ctr/index-j.htm), identification number: UMIN000005703.

Artificial Conditioner for Stored Organs

We have developed an artificial organ conditioning system in order not only to condition but also evaluate the viability for transplant graft of kidneys which have been stored for a long time and damaged by warm ischaemia following cardiac arrest. The conditioning system consisted of an artificial lung, a roller pump, an organ chamber and perfusate. The perfusate was prepared with electrolytes, fluorocarbon, amino acid, glucose, an oxygen scavenger and so on. Conditioning was performed by continuous perfusion under mild hypothermia at 24° C. Mildly damaged kidneys (0 and 30 minutes warm ischaemia rabbit kidneys) were well conditioned but severely damaged kidneys failed to produce urination. Our device successfully exposed the viability of stored kidneys and the successful conditioning of damaged kidneys due to warm ischaemia avoiding transplantation. By establishing our method, the harvesting of kidneys following cardiac arrest will be feasible.

Co-Opted Megasatellite DNA Drives Evolution of Secondary Night Vision in Azara's Owl Monkey

Owl monkeys (genus Aotus) are the only taxon in simian primates that consists of nocturnal or otherwise cathemeral species. Their night vision is superior to that of other monkeys, apes, and humans but not as good as that of typical nocturnal mammals. This incomplete night vision has been used to conclude that these monkeys only secondarily adapted to a nocturnal lifestyle, or to their cathemeral lifestyle that involves high night-time activity. It is known that the rod cells of many nocturnal mammals possess a unique nuclear architecture in which heterochromatin is centrally located. This "inverted nuclear architecture", in contrast with "conventional nuclear architecture", provides elevated night vision by passing light efficiently to the outer segments of photoreceptors. Owl monkey rod cells exhibit an intermediate chromatin distribution, which may provide them with less efficient night vision than other nocturnal mammals. Recently, we identified three megasatellite DNAs in the genome of Azara's owl monkey (Aotus azarae). In the present study, we show that one of the three megasatellite DNAs, OwlRep, serves as the primary component of the heterochromatin block located in the central space of the rod nucleus in A. azarae. This satellite DNA is likely to have emerged in the Aotus lineage after its divergence from those of other platyrrhini taxa and underwent a rapid expansion in the genome. Our results indicate that the heterochromatin core in the A. azarae rod nucleus was newly formed in A. azarae or its recent ancestor, and supports the hypothesis that A. azarae, and with all probability other Aotus species, secondarily acquired night vision.

Direct estimation of de novo mutation rates in a chimpanzee parent-offspring trio by ultra-deep whole genome sequencing

Mutations generate genetic variation and are a major driving force of evolution. Therefore, examining mutation rates and modes are essential for understanding the genetic basis of the physiology and evolution of organisms. Here, we aim to identify germline de novo mutations through the whole-genome surveyance of Mendelian inheritance error sites (MIEs), those not inherited through the Mendelian inheritance manner from either of the parents, using ultra-deep whole genome sequences (>150-fold) from a chimpanzee parent-offspring trio. We identified such 889 MIEs and classified them into four categories based on the pattern of inheritance and the sequence read depth: [i] de novo single nucleotide variants (SNVs), [ii] copy number neutral inherited variants, [iii] hemizygous deletion inherited variants, and [iv] de novo copy number variants (CNVs). From de novo SNV candidates, we estimated a germline de novo SNV mutation rate as 1.48 × 10^-8 per site per generation or 0.62 × 10^-9 per site per year. In summary, this study demonstrates the significance of ultra-deep whole genome sequencing not only for the direct estimation of mutation rates but also for discerning various mutation modes including de novo allelic conversion and de novo CNVs by identifying MIEs through the transmission of genomes from parents to offspring.

X Chromosome Introgression and Recombination in the cephus Group of Cercopithecus Monkeys

A representative of Cercopithecus erythrotis was surveyed at a 9.3-kb region of the X chromosome. The data were compared against homologous sequences of closely related Cercopithecus monkeys including C. cephus, a species recently shown to have 2 polymorphic X-chromosomal lineages. Direct sequence comparisons and subsequent phylogenetic analyses revealed that synapomorphies in the first 4.3 kb cluster C. erythrotis with one C. cephus lineage, while synapomorphies in the latter 5.0 kb join it with the second C. cephus lineage. This pattern very likely reflects an ancestral episode of introgression from C. cephus into C. erythrotis followed by a recombination event. Similar groups of synapomorphies occur at different phylogenetic depths within the C. erythrotis/C. cephus/C. ascanius radiation and reveal new details in the evolutionary history of this 3-species clade.

Constitutively active ABL family kinases, TEL/ABL and TEL/ARG, harbor distinct leukemogenic activities in vivo

ABL (ABL1) and ARG (ABL2) are highly homologous to each other in overall domain structure and amino-acid sequence, with the exception of their C termini. As with ABL, translocations that fuse ARG to ETV6/TEL have been identified in patients with leukemia. To assess the in vivo leukemogenic activity of constitutively active ABL and ARG, we generated a bone marrow (BM) transplantation model using the chimeric forms TEL/ABL and TEL/ARG, which have comparable kinase activities. TEL/ABL rapidly induced fatal myeloid leukemia in recipient mice, whereas recipients of TEL/ARG-transduced cells did not develop myeloid leukemia, instead, they succumbed to a long-latency infiltrative mastocytosis that could be adoptively transferred to secondary recipients. Swapping of the C termini of ABL and ARG altered disease latency and phenotypes. In a detailed in vitro study, TEL/ARG strongly promoted mast cell differentiation in response to stem cell factor or interleukin-3, whereas TEL/ABL preferentially induced myeloid differentiation of hematopoietic stem/progenitor cells. These results indicate that ABL and ARG kinase activate distinct differentiation pathways to induce specific diseases in vivo, that is, myeloid leukemia and mastocytosis, respectively. Further elucidation of the differences in their properties should provide important insight into the pathogenic mechanisms of oncogenes of the ABL kinase family.

Night Monkey Hybrids Exhibit De Novo Genomic and Karyotypic Alterations: The First Such Case in Primates

Using molecular chromosomal analyses, we discovered night monkey hybrids produced in captivity from matings between a female Aotus azarae boliviensis (2n = 50) and a male Aotus lemurinus griseimembra (2n = 53). The parents produced seven offspring in total, including one male and six females-a pattern consistent with Haldane's rule. Chromosomal studies were conducted on four of the hybrid offspring. Two of them showed relatively "simple" mixture karyotypes, including different chromosome numbers (2n = 51, 52), which were formed because of a heteromorphic autosome pair in the father (n = 26, 27). The other two hybrid monkeys exhibited de novo genomic and karyotypic alterations. Detailed analysis of the alterations revealed that one individual carried a mixture karyotype of the two parental species and an X chromosome trisomy (53,XXX). The second individual displayed trisomy of chromosome 18 (52,XX,+18) and a reciprocal translocation between autosomes 21 and 23 (52,XX,+18,t(21;23)). Interestingly, the second monkey exhibited mosaicism among blood cells (mos52,XX,+18[87]/52,XX,+18,t(21;23)[85]), but only a single karyotype (52,XX,+18) in skin fibroblast cells. The X- and 18-trisomies were derived from a doubling of the mother's chromosomes in early embryonic cell division, and the reciprocal translocation likely developed in the bone marrow of the offspring, considering that it was observed only in blood cells. Such occurrence of trisomies in hybrid individuals is a unique finding in placental mammals.

Chimpanzee Down syndrome: a case study of trisomy 22 in a captive chimpanzee

We report a case of chimpanzee trisomy 22 in a captive-born female. Because chromosome 22 in great apes is homologous to human chromosome 21, the present case is analogous to human trisomy 21, also called Down syndrome. The chimpanzee in the present case experienced retarded growth; infantile cataract and vision problems, including nystagmus, strabismus, and keratoconus; congenital atrial septal defect; and hypodontia. All of these symptoms are common in human Down syndrome. This case was the second reported case of trisomy 22 in the chimpanzee. The chimpanzee in our case became blind by 7 years old, making social life with other chimpanzees difficult, but opportunities to interact with other conspecific individuals have been offered routinely. We believe that providing her with the best care over the course of her life will be essential.

CENP-B box, a nucleotide motif involved in centromere formation, occurs in a New World monkey

Centromere protein B (CENP-B) is one of the major proteins involved in centromere formation, binding to centromeric repetitive DNA by recognizing a 17 bp motif called the CENP-B box. Hominids (humans and great apes) carry large numbers of CENP-B boxes in alpha satellite DNA (AS, the major centromeric repetitive DNA of simian primates). Only negative results have been reported regarding the presence of the CENP-B box in other primate taxa. Consequently, it is widely believed that the CENP-B box is confined, within primates, to the hominids. We report here that the common marmoset, a New World monkey, contains an abundance of CENP-B boxes in its AS. First, in a long contig sequence we constructed and analysed, we identified the motif in 17 of the 38 alpha satellite repeat units. We then sequenced terminal regions of additional clones and found the motif in many of them. Immunostaining of marmoset cells demonstrated that CENP-B binds to DNA in the centromeric regions of chromosomes. Therefore, functional CENP-B boxes are not confined to hominids. Our results indicate that the efficiency of identification of the CENP-B box may depend largely on the sequencing methods used, and that the CENP-B box in centromeric repetitive DNA may be more common than researchers previously thought.

Hypervariability of Nucleolus Organizer Regions in Bengal Slow Lorises, Nycticebus bengalensis (Primates, Lorisidae)

Slow lorises are a cryptic species complex, and thus genetic markers are needed to identify distinct evolutionary lineages or species. We examined the nucleolus organizer regions (NORs) of Bengal slow lorises (Nycticebus bengalensis) using FISH with 18S rDNA (rDNA-FISH) and silver nitrate staining (Ag-NOR stain). Ten individuals of the putatively single species N. bengalensis showed higher variability in localization than 3 other congeners, though their overall karyotypes were similar. The rDNA-FISH analysis detected a total of 18 loci, in contrast to previous studies of other slow loris species that revealed far fewer (6-10) loci. Eight of the 18 loci detected in the present analysis were found to be semi-stable localizations at 4 different chromosomes, while 10 were found to be unstable localizations at 5 other chromosomes. The semi-stable locations showed occasional presence/absence of variations for rDNA-FISH, and unstable locations were polymorphic among individuals, contributing to the higher variability of NORs in this taxon. We hypothesize that the larger numbers of rDNA loci found in N. bengalensis were introduced by genomic dispersion through ectopic recombination in association with terminal regions including rDNA. Such differences are potentially very powerful chromosomal markers to be used in species identification and conservation.

Amino acid residues of bitter taste receptor TAS2R16 that determine sensitivity in primates to β-glycosides

In mammals, bitter taste is mediated by TAS2Rs, which belong to the family of seven transmembrane G protein-coupled receptors. Since TAS2Rs are directly involved in the interaction between mammals and their dietary sources, it is likely that these genes evolved to reflect species-specific diets during mammalian evolution. Here, we analyzed the amino acids responsible for the difference in sensitivities of TAS2R16s of various primates using a cultured cell expression system. We found that the sensitivity of TAS2R16 varied due to several amino acid residues. Mutation of amino acid residues at E86T, L247M, and V260F in human and langur TAS2R16 for mimicking the macaque TAS2R16 decreased the sensitivity of the receptor in an additive manner, which suggests its contribution to the potency of salicin, possibly via direct interaction. However, mutation of amino acid residues 125 and 133 in human TAS2R16, which are situated in helix 4, to the macaque sequence increased the sensitivity of the receptor. These results suggest the possibility that bitter taste sensitivities evolved independently by replacing specific amino acid residues of TAS2Rs in different primate species to adapt to species-specific food.

Formation of functional CENP-B boxes at diverse locations in repeat units of centromeric DNA in New World monkeys

Centromere protein B, which is involved in centromere formation, binds to centromeric repetitive DNA by recognizing a nucleotide motif called the CENP-B box. Humans have large numbers of CENP-B boxes in the centromeric repetitive DNA of their autosomes and X chromosome. The current understanding is that these CENP-B boxes are located at identical positions in the repeat units of centromeric DNA. Great apes also have CENP-B boxes in locations that are identical to humans. The purpose of the present study was to examine the location of CENP-B box in New World monkeys. We recently identified CENP-B box in one species of New World monkeys (marmosets). In this study, we found functional CENP-B boxes in CENP-A-assembled repeat units of centromeric DNA in 2 additional New World monkeys (squirrel monkeys and tamarins) by immunostaining and ChIP-qPCR analyses. The locations of the 3 CENP-B boxes in the repeat units differed from one another. The repeat unit size of centromeric DNA of New World monkeys (340–350 bp) is approximately twice that of humans and great apes (171 bp). This might be, associated with higher-order repeat structures of centromeric DNA, a factor for the observed variation in the CENP-B box location in New World monkeys.

Rapid Expansion of Phenylthiocarbamide Non-Tasters among Japanese Macaques

Bitter taste receptors (TAS2R proteins) allow mammals to detect and avoid ingestion of toxins in food. Thus, TAS2Rs play an important role in food choice and are subject to complex natural selection pressures. In our previous study, we examined nucleotide variation in TAS2R38, a gene expressing bitter taste receptor for phenylthiocarbamide (PTC), in 333 Japanese macaques (Macaca fuscata) from 9 local populations in Japan. We identified a PTC “non-taster” TAS2R38 allele in Japanese macaques that was caused by a loss of the start codon. This PTC non-taster allele was only found in a limited local population (the Kii area), at a frequency of 29%. In this study, we confirmed that this allele was present in only the Kii population by analyzing an additional 264 individuals from eight new populations. Using cellular and behavioral experiments, we found that this allele lost its receptor function for perceiving PTC. The nucleotide sequences of the allele including flanking regions (of about 10 kb) from 23 chromosomes were identical, suggesting that a non-taster allele arose and expanded in the Kii population during the last 13,000 years. Genetic analyses of non-coding regions in Kii individuals and neighboring populations indicated that the high allele frequency in the Kii population could not be explained by demographic history, suggesting that positive selection resulted in a rapid increase in PTC non-tasters in the Kii population. The loss-of-function that occurred at the TAS2R38 locus presumably provided a fitness advantage to Japanese macaques in the Kii population. Because TAS2R38 ligands are often found in plants, this functional change in fitness is perhaps related to feeding habit specificity. These findings should provide valuable insights for elucidating adaptive evolutionary changes with respect to various environments in wild mammals.

Novel variable number of tandem repeats of gibbon MAOA gene and its evolutionary significance

Variable number of tandem repeats (VNTRs) are scattered throughout the primate genome, and genetic variation of these VNTRs have been accumulated during primate radiation. Here, we analyzed VNTRs upstream of the monoamine oxidase A (MAOA) gene in 11 different gibbon species. An abundance of truncated VNTR sequences and copy number differences were observed compared to those of human VNTR sequences. To better understand the biological role of these VNTRs, a luciferase activity assay was conducted and results indicated that selected VNTR sequences of the MAOA gene from human and three different gibbon species (Hylobates klossii, Hylobates lar, and Nomascus concolor) showed silencing ability. Together, these data could be useful for understanding the evolutionary history and functional significance of MAOA VNTR sequences in gibbon species.

Higher-order repeat structure in alpha satellite DNA occurs in New World monkeys and is not confined to hominoids

Centromeres usually contain large amounts of tandem repeat DNA. Alpha satellite DNA (AS) is the most abundant tandem repeat DNA found in the centromeres of simian primates. The AS of humans contains sequences organized into higher-order repeat (HOR) structures, which are tandem arrays of larger repeat units consisting of multiple basic repeat units. HOR-carrying AS also occurs in other hominoids, but results reported to date for phylogenetically more remote taxa have been negative. Here we show direct evidence for clear HOR structures in AS of the owl monkey and common marmoset. These monkeys are New World monkey species that are located phylogenetically outside of hominoids. It is currently postulated that the presence of HOR structures in AS is unique to hominoids. Our results suggest that this view must be modified. A plausible explanation is that generation of HOR structures is a general event that occurs occasionally or frequently in primate centromeres, and that, in humans, HOR-carrying AS became predominant in the central region of the centromere. It is often difficult to assemble sequence reads of tandem repeat DNAs into accurate contig sequences; our careful sequencing strategy allowed us to overcome this problem.

The development of laboratory tests for cancer in Japan with special reference to carcinoembryonic proteins

The present paper describes the present status of clinical tests for cancer in Japan. Since no cancer-specific substance has been found so far the clinical tests for cancer at present are always quantitative but not qualitative. Among these substances, alpha-fetoprotein is one of the most specific substances for cancer and its test is essential for diagnosis of hepatoma beins used worldwide. AFP is a specific product of liver cancer cells. The measurement of carcinoembryonic antigen in patient blood is a hopeful method for cancer diagnosis. This substance is not specifically produced by cancer cells, but the phenomenon of appearance in bloodstream appears to be cancer-specific. This may reflect the invasion of blood vessels in tissues such as colorectum, lung, etc., by infiltration of cancer cell. This is the reason for the appearance of CEA in a wide variety of cancers. There are many other clinical tests at present but these are only secondary aids for the diagnosis of cancer. This is the reason why the description concentrates mostly on AFP and CEA. The companies manufacturing the kits for these tests in Japan are also listed in this paper.

Emergence of infectious malignant thrombocytopenia in Japanese macaques (Macaca fuscata) by SRV-4 after transmission to a novel host

We discovered a lethal hemorrhagic syndrome arising from severe thrombocytopenia in Japanese macaques kept at the Primate Research Institute, Kyoto University. Extensive investigation identified that simian retrovirus type 4 (SRV-4) was the causative agent of the disease. SRV-4 had previously been isolated only from cynomolgus macaques in which it is usually asymptomatic. We consider that the SRV-4 crossed the so-called species barrier between cynomolgus and Japanese macaques, leading to extremely severe acute symptoms in the latter. Infectious agents that cross the species barrier occasionally amplify in virulence, which is not observed in the original hosts. In such cases, the new hosts are usually distantly related to the original hosts. However, Japanese macaques are closely related to cynomolgus macaques, and can even hybridize when given the opportunity. This lethal outbreak of a novel pathogen in Japanese macaques highlights the need to modify our expectations about virulence with regards crossing species barriers.

Locational diversity of alpha satellite DNA and intergeneric hybridization aspects in the Nomascus and Hylobates genera of small apes

Recently, we discovered that alpha satellite DNA has unique and genus-specific localizations on the chromosomes of small apes. This study describes the details of alpha satellite localization in the genera Nomascus and Hylobates and explores their usefulness in distinguishing parental genome sets in hybrids between these genera. Fluorescence in situ hybridization was used to establish diagnostic criteria of alpha satellite DNA markers in discriminating small ape genomes. In particular we established the genus specificity of alpha satellite distribution in three species of light-cheeked gibbons (Nomascus leucogenys, N. siki, and N. gabriellae) in comparison to that of Hylobates lar. Then we determined the localization of alpha satellite DNA in a hybrid individual which resulted from a cross between these two genera. In Nomascus the alpha satellite DNA blocks were located at the centromere, telomere, and four interstitial regions. In Hylobates detectable amounts of alpha satellite DNA were seen only at centromeric regions. The differences in alpha satellite DNA locations between Nomascus and Hylobates allowed us to easily distinguish the parental chromosomal sets in the genome of intergeneric hybrid individuals found in Thai and Japanese zoos. Our study illustrates how molecular cytogenetic markers can serve as diagnostic tools to identify the origin of individuals. These molecular tools can aid zoos, captive breeding programs and conservation efforts in managing small apes species. Discovering more information on alpha satellite distribution is also an opportunity to examine phylogenetic and evolutionary questions that are still controversial in small apes.

Short communication: expression profiles of endogenous retroviral envelopes in Macaca mulatta (rhesus monkey)

Endogenous retroviruses (ERVs), which are footprints of ancient germline infections, were inserted into the genome during the early stages of primate evolution. Human endogenous retroviruses (HERVs) occupy approximately 8% of the human genome. Although most ERV genes are defective, with large deletions, stop codons, and frameshifts in their open reading frames (ORFs), some full-length sequences containing long ORFs are expressed in several tissues and cancers. Several envelope glycoproteins that are encoded by env genes have retained some characteristics of their ancestral infectious viruses. These glycoproteins play essential physiological roles in the organs in which they are expressed. Previous studies have demonstrated the expression of ERV env at the mRNA level in cells and tissues rather than at the protein level, which is more difficult to detect. However, it is not known whether Env is functionally conserved in primates. To understand the possible role of Env in primates, we examined the expression of the env genes of four ERVs (ERV-R, -K, -W, and -FRD) at the protein as well as mRNA levels in various tissues of the rhesus monkey. The ERV env gene products were observed at moderate to high levels in each tissue that was examined and showed tissue-specific expression patterns. Our data suggest a biologically important role for retroviral proteins in healthy tissues of the rhesus monkey.

Chromosomal differentiation of schistosomes: what is the message?

As the only group of flukes with dioecism, schistosomes are unique organisms; they not only have intriguing biological and evolutionary aspects but also are responsible for major public health problems in the developing world. Schistosomiasis caused by this fluke affects approximately 210 million people in 76 countries. In order to facilitate the discovery of eradication methods for this disease, fundamental biological outcomes must be made available. Whole genome sequence data represent one such resource applicable to discovering eradication methods and measures. Herein, I describe three remarkable chromosomal changes and briefly discuss the differentiation of the Asian and African groups of this parasite taxon. Chromosomal data and evolutionary aspects will enable us to exploit genomic information for advancing schistosome studies.

Evolutionary origin of higher-order repeat structure in alpha-satellite DNA of primate centromeres

Alpha-satellite DNA (AS) is a main DNA component of primate centromeres, consisting of tandemly repeated units of ∼170 bp. The AS of humans contains sequences organized into higher-order repeat (HOR) structures, in which a block of multiple repeat units forms a larger repeat unit and the larger units are repeated tandemly. The presence of HOR in AS is widely thought to be unique to hominids (family Hominidae; humans and great apes). Recently, we have identified an HOR-containing AS in the siamang, which is a small ape species belonging to the genus Symphalangus in the family Hylobatidae. This result supports the view that HOR in AS is an attribute of hominoids (superfamily Hominoidea) rather than hominids. A single example is, however, not sufficient for discussion of the evolutionary origin of HOR-containing AS. In the present study, we developed an efficient method for detecting signs of large-scale HOR and demonstrated HOR of AS in all the three other genera. Thus, AS organized into HOR occurs widely in hominoids. Our results indicate that (i) HOR-containing AS was present in the last common ancestor of hominoids or (ii) HOR-containing AS emerged independently in most or all basal branches of hominoids. We have also confirmed HOR occurrence in centromeric AS in the Hylobatidae family, which remained unclear in our previous study because of the existence of AS in subtelomeric regions, in addition to centromeres, of siamang chromosomes.

Heterochromatin blocks constituting the entire short arms of acrocentric chromosomes of Azara's owl monkey: formation processes inferred from chromosomal locations

Centromeres and telomeres of higher eukaryotes generally contain repetitive sequences, which often form pericentric or subtelomeric heterochromatin blocks. C-banding analysis of chromosomes of Azara's owl monkey, a primate species, showed that the short arms of acrocentric chromosomes consist mostly or solely of constitutive heterochromatin. The purpose of the present study was to determine which category, pericentric, or subtelomeric is most appropriate for this heterochromatin, and to infer its formation processes. We cloned and sequenced its DNA component, finding it to be a tandem repeat sequence comprising 187-bp repeat units, which we named OwlRep. Subsequent hybridization analyses revealed that OwlRep resides in the pericentric regions of a small number of metacentric chromosomes, in addition to the short arms of acrocentric chromosomes. Further, in the pericentric regions of the acrocentric chromosomes, OwlRep was observed on the short-arm side only. This distribution pattern of OwlRep among chromosomes can be simply and sufficiently explained by assuming (i) OwlRep was transferred from chromosome to chromosome by the interaction of pericentric heterochromatin, and (ii) it was amplified there as subtelomeric heterochromatin. OwlRep carries several direct and inverted repeats within its repeat units. This complex structure may lead to a higher frequency of chromosome scission and may thus be a factor in the unique distribution pattern among chromosomes. Neither OwlRep nor similar sequences were found in the genomes of the other New World monkey species we examined, suggesting that OwlRep underwent rapid amplification after the divergence of the owl monkey lineage from lineages of the other species.