Excess amino acid polymorphism in mitochondrial DNA: contrasts among genes from Drosophila, mice, and humans

Recent studies of mitochondrial DNA (mtDNA) variation in mammals and Drosophila have shown an excess of amino acid variation within species (replacement polymorphism) relative to the number of silent and replacement differences fixed between species. To examine further this pattern of nonneutral mtDNA evolution, we present sequence data for the ND3 and ND5 genes from 59 lines of Drosophila melanogaster and 29 lines of D. simulans. Of interest are the frequency spectra of silent and replacement polymorphisms, and potential variation among genes and taxa in the departures from neutral expectations. The Drosophila ND3 and ND5 data show no significant excess of replacement polymorphism using the McDonald-Kreitman test. These data are in contrast to significant departures from neutrality for the ND3 gene in mammals and other genes in Drosophila mtDNA (cytochrome b and ATPase 6). Pooled across genes, however, both Drosophila and human mtDNA show very significant excesses of amino acid polymorphism. Silent polymorphisms at ND5 show a significantly higher variance in frequency than replacement polymorphisms, and the latter show a significant skew toward low frequencies (Tajima's D = -1.954). These patterns are interpreted in light of the nearly neutral theory where mildly deleterious amino acid haplotypes are observed as ephemeral variants within species but do not contribute to divergence. The patterns of polymorphism and divergence at charge-altering amino acid sites are presented for the Drosophila ND5 gene to examine the evolution of functionally distinct mutations. Excess charge-altering polymorphism is observed at the carboxyl terminal and excess charge-altering divergence is detected at the amino terminal. While the mildly deleterious model fits as a net effect in the evolution of nonrecombining mitochondrial genomes, these data suggest that opposing evolutionary pressures may act on different regions of mitochondrial genes and genomes.      

Abdominal cysticercosis in a rhesus macaque (Macaca mulatta)

A mid-abdominal mass was discovered during routine physical examination of a rhesus macaque (Macaca mulatta). Further diagnostics and exploratory laparotomy were performed, revealing a fluid-filled cyst attached to the caudal free margin of the greater omentum. Formation and pulsatile movement of white-colored circumferential bands within the wall of the cyst were observed during surgery. The cyst was removed and later was dissected. The discovery of a single invaginated scolex identified the cyst as a cysticercus. The location and characteristics of the cysticercus were consistent with the larval form of Taenia hydatigena.     

Spatial representation along the proximodistal axis of CA1

CA1 cells receive direct input from space-responsive cells in medial entorhinal cortex (MEC), such as grid cells, as well as more nonspatial cells in lateral entorhinal cortex (LEC). Because MEC projects preferentially to the proximal part of the CA1, bordering CA2, whereas LEC innervates only the distal part, bordering subiculum, we asked if spatial tuning is graded along the transverse axis of CA1. Tetrodes were implanted along the entire proximodistal axis of dorsal CA1 in rats. Data were recorded in cylinders large enough to elicit firing at more than one location in many neurons. Distal CA1 cells showed more dispersed firing and had a larger number of firing fields than proximal cells. Phase-locking of spikes to MEC theta oscillations was weaker in distal CA1 than in proximal CA1. The findings suggest that spatial firing in CA1 is organized transversally, with the strongest spatial modulation occurring in the MEC-associated proximal part.     

Fxna, a novel gene differentially expressed in the rat ovary at the time of folliculogenesis, is required for normal ovarian histogenesis

In rodents, the formation of ovarian follicles occurs after birth. In recent years, several factors required for follicular assembly and the growth of the newly formed follicles have been identified. We now describe a novel gene, Fxna, identified by differential display in the neonatal rat ovary. Fxna encodes an mRNA of 5.4 kb, and a protein of 898 amino acids. Fxna is a transmembrane metallopeptidase from family M28, localized to the endoplasmic reticulum. In the ovary, Fxna mRNA is expressed in granulosa cells; its abundance is maximal 48 hours after birth, i.e. during the initiation of follicular assembly. Reducing Fxna mRNA levels via lentiviral-mediated delivery of short hairpin RNAs to neonatal ovaries resulted in substantial loss of primordial, primary and secondary follicles, and structural disorganization of the ovary, with many abnormal follicles containing more than one oocyte and clusters of somatic cells not associated with any oocytes. These abnormalities were not attributable to either increased apoptosis or decreased proliferation of granulosa cells. The results indicate that Fxna is required for the organization of somatic cells and oocytes into discrete follicular structures. As an endoplasmic reticulum-bound peptidase, Fxna may facilitate follicular organization by processing precursor proteins required for intraovarian cell-to-cell communication.     

A direct method for the synthesis of orthogonally protected furyl- and thienyl- amino acids

The synthesis of unnatural amino acids plays a key part in expanding the potential application of peptide-based drugs and in the total synthesis of peptide natural products. Herein, we report a direct method for the synthesis of orthogonally protected 5-membered heteroaromatic amino acids.     

An Outbreak of Tularemia in a Colony of Outdoor-Housed Rhesus Macaques (Macaca mulatta)

Since an epizootic and detection of clinical cases of tularemia (Francisella tularensis) in 1996 at the Oregon National Primate Research Center, only 8 cases were identified in the succeeding 13 y. However, within a period of 7 mo, primarily during Winter 2010, 6 rhesus macaques were confirmed positive for Francisella tularensis type B by the Centers for Disease Control and Prevention by culture and fluorescent antibody testing. All cases had similar gross pathologic findings, which included necrotizing splenitis and lymphadenitis. Recent colony management efforts have focused on minimizing nonhuman primate exposure to commonly observed reservoir species and controlling rodent access to corral-style housing. Strategies continue to evolve with regard to managing a large breeding colony of nonhuman primates in the presence of this threat.Abbreviation: ONPRC, Oregon National Primate Research CenterFrancisella tularensis, the causative agent of tularemia, is a small pleomorphic gram-negative coccobacillus.¹¹ Severe disease and potentially death in humans can result from exposure to as few as 10 cfu of this highly infectious organism.^7,10 The disease is also known as rabbit fever and deer-fly fever, reflecting 2 common sources of infection for humans.³ F. tularensis is classified by the United States Department of Health and Human Services as a Category A Select Agent.⁶ It is considered a potential agent of biologic warfare, and in fact, has been weaponized and stockpiled in the past.¹⁰ The 2 biovars that are referenced most frequently in published human and nonhuman primate literature are tularensis (type A) and holarctica (formerly paleartica; type B).^4,12,13,23 An additional biovar, novicida (type C), has been described, but its virulence in humans is decreased due to its lack of a capsule.¹⁰Tularemia is endemic to many parts of the northern hemisphere, which includes the region surrounding the Oregon National Primate Research Center (ONPRC), an AAALAC-accredited facility.²⁰ Tularemia has one of the broadest host ranges of all bacteria, encompassing well over 200 mammalian species primarily, in addition to birds, amphibians, fish, and various arthropods such as fleas, ticks, mosquitoes, and flies.^10,15,19,20 The ONPRC is located in a mixed forest and field environment which is bordered by wetlands and residential neighborhoods outside of Portland. More than 4500 nonhuman primates are housed here, and most live outdoors in breeding groups. Therefore, exposure to this potentially life-threatening and zoonotic pathogen is inevitable, due to its persistence in the environment and the close proximity of several reservoir species. Presumed reservoir species commonly observed at ONPRC include meadow voles (Microtus pennsylvanicus), brown rats (Rattus norvegicus), deer mice (genus Peromyscus), house mice (Mus musculus), and California ground squirrels (Spermophilus beecheyi). Potential arthropod vectors that are monitored regularly at ONPRC include biting flies and mosquitoes. At this time, testing of prospective rodent carriers for tularemia is ongoing; therefore, in the interest of caution, all of the rodent and arthropod species listed are considered potential carriers of the disease.Tularemia was first recognized at the ONPRC in 1996 during an epizootic that resulted in 24 deaths among corral-housed rhesus macaques. Serology results from banked sera and sera collected during and after the outbreak demonstrated a seroconversion rate of approximately 25% in 723 animals. During the succeeding 13 y, only 8 sporadic cases were diagnosed. However, within a period of 3 mo during the winter of 2010, 5 rhesus macaques were diagnosed with Francisella tularensis type B by the Centers for Disease Control and Prevention (Atlanta, GA). Four months later, an additional case was confirmed. All 6 macaques were younger than 1 y and were assigned to a breeding colony protocol approved by the ONPRC Animal Care and Use Committee. The current report describes the clinical signs and gross and histologic findings associated with these cases, as well as methods for prevention and control of future cases of disease.     

A radioimmunoprecipitation method in the serodiagnosis of HIV infection: the development of the optimal conditions for its performance and the evaluation of the possibilities for its use

The optimum conditions for using the method of radioimmunoprecipitation (RIP) for the detection of human immunodeficiency virus (HIV) in serum samples have been established. Out of several available cell lines persistently infected with HIV, specially selected line 17 has been chosen. The characteristic feature of this is the high and stable (under the conditions of prolonged cultivation) accumulation of virus-specific proteins in infected cells. The optimum conditions for making the test and its evaluation have also been established. The data of literature on the advantages of the method of RIP over such traditional methods as the enzyme immunoassay and immunoblotting have been confirmed. Thus, the presence of specific antibodies in several serum samples registered as false negative has been established. The intertypical reactivity of two serotypes of the virus, HIV-1 and HIV-2, has been studied. Cross reactivity of antibodies with respect to the HIV gene gag, but not with respect to viral glycoproteids, has been established. Ideas on the expediency and prospects of using RIP for the serological control of HIV infection are presented.