Application of a multidisciplinary approach to the systematics of Acomys (Rodentia : Muridae) from northern Tanzania

The systematic status and geographic distribution of spiny mice of the genus Acomys I. Geoffroy, 1838 in northern Tanzania is uncertain. This study assesses the systematic and geographic distribution of Acomys from northern Tanzania using a multidisciplinary approach that includes molecular, cytogenetic, traditional and geometric morphometric analyses, and classical morphology of the same individuals. The molecular analysis was based on 1140 base pairs (bp) of the mitochondrial cytochrome b and 1297 bp of the nuclear interphotoreceptor retinoid binding protein (IRBP) gene sequences. These data were subjected to phylogenetic analyses using Maximum likelihood, Bayesian, Maximum parsimony, and Minimum evolution analyses. The cytogenetic analysis included G-banding of metaphase chromosomes. The morphometric analyses included univariate and multivariate analyses of traditional morphometric measurements of the cranium and mandible, and of geometric morphometric two-dimensional landmarks of the dorsal, ventral, and lateral views of the cranium, and lateral view of mandible that included thin-plate spline (TPS) analysis. The classical morphology included examination of external, cranial and mandibular morphology. Results of all these multidisciplinary analyses were congruent and provide evidence for the occurrence of two sympatric species of Acomys in northern Tanzania, namely, the previously recorded A. wilsoni (2n = 62) and a newly recorded A. cf. percivali (2n = 58). These results that also represent the first reported mitochondrial cytochrome b and nuclear IRBP gene sequences and karyotype for A. cf. percivali, increases the number of species known to occur in Tanzania from four to five. However, the mitochondrial cytochrome b data that included GenBank sequences from the type locality in Kenya suggest that A. wilsoni may not be monophyletic. Ecologically, the two species seem to partition their niches with A. cf. percivali being found in well-covered habitats with thorn bushes, rocky and mountainous areas, and A. wilsoni being found in open semi-arid grasslands as well as in rice fields. The two species appear to be isolated by complex natural barriers formed by the Great East African Rift Valley whose geological features have generally been associated with active rodent speciation. However, the present results need further multidisciplinary investigation involving extensive sampling and examination of topotypical material. CopyrightDissertation (MSc)--University of Pretoria, 2008.Zoology and Entomologyunrestricte

The pattern of reproduction in the mole-rat Heliophobius from Tanzania : do not refrain during the long rains!

The genus Heliophobius comprises of at least six cryptic, topotypical species in the Heliophobius argentocinereus species complex. The current study investigated the breeding patterns of a wildcaught population from Tanzania where the putative species H. emini resides. Individuals were collected on a monthly basis for an entire calendar year. Assessment of foetus presence, gonadal histology, reproductive tract morphometrics in combination with gonadal steroid (plasma progesterone and oestradiol-17β in females and testosterone in males) measurements and field observations revealed that rainfall is important for the onset of breeding. The results further confirmed that breeding is limited to a single, yearly reproductive event synchonised to the long rainfall pattern. The distinct breeding peak in July is associated with an elevation in gonadal mass, increase in concentrations of reproductive hormones and presence of Graafian follicles and corpora lutea in the ovaries of females. These reproductive parameters coincided with the end of the long rainfall period, whereas presence of young in the maternal burrow system corresponded with the start of the short rainfall of East Africa. These findings confirm Heliophobius has a single breeding opportunity each year, and this species is therefore vulnerable to any changes that may impact their climatically attuned breeding patterns.MKN was sponsored by a student bursary from DAAD in Germany. NCB acknowledges funding from the South African DST/NRF SARChI Chair for Mammal Behavioural Ecology and Physiology, University of Pretoria.http://www.nrcresearchpress.com/journal/cjzhb2017Mammal Research InstituteZoology and Entomolog

Selected Endemic Zoonoses in Pigs Presenting for Slaughter in Kampala, Uganda

Leptospirosis, brucellosis, and Q fever (coxiellosis) are bacterial zoonoses that cause acute febrile illness in people as well as reproductive losses in pigs. Pig keeping is an increasingly important livelihood to millions of smallholder farmers in Uganda because of exponential increases in demand for pork. The prevalence of leptospirosis and Q fever in pigs is unknown, and the few studies of porcine brucellosis have estimated a range of seroprevalence. Therefore, we undertook a prevalence survey of leptospirosis, brucellosis, and Q fever in pigs using quantitative real-time PCR to determine the potential importance of these zoonoses to the growing pig sector in Uganda. Six hundred forty-nine pigs were sampled in 2015–2016 at an urban pork slaughterhouse. Ten percent of pigs (n = 68) had leptospiral DNA in either their kidney or reproductive tissue. In adjusted analyses, variables predictive of leptospiral status included female sex (odds ratio [OR]: 2.37,P< 0.01) and pigs sampled in March 2016 (OR: 2.23,P= 0.02) and October 2016 (OR: 0.30,P= 0.04). DNA fingerprinting revealed circulation of at least four distinct serovars in these pigs. Brucella spp. and Coxiella burnetii DNA were not detected in any sampled pig. This is the first report of widespread circulation of pathogenic Leptospira spp. in pigs in Uganda, suggesting that leptospirosis likely has a greater impact on the health of pigs than was previously recognized. Pig farmers, pig traders, and slaughterhouse workers may be at greatest occupational risk because of their direct contact with infective leptospires in aborted fetuses, bodily fluids, and other tissues

Leptospira Serovars for Diagnosis of Leptospirosis in Humans and Animals in Africa: Common Leptospira Isolates and Reservoir Hosts

The burden of leptospirosis in humans and animals in Africa is higher than that reported from other parts of the world. However, the disease is not routinely diagnosed in the continent. One of major factors limiting diagnosis is the poor availability of live isolates of locally circulating Leptospira serovars for inclusion in the antigen panel of the gold standard microscopic agglutination test (MAT) for detecting antibodies against leptospirosis. To gain insight in Leptospira serovars and their natural hosts occurring in Tanzania, concomitantly enabling the improvement of the MAT by inclusion of fresh local isolates, a total of 52 Leptospira isolates were obtained from fresh urine and kidney homogenates, collected between 1996 and 2006 from small mammals, cattle and pigs. Isolates were identified by serogrouping, cross agglutination absorption test (CAAT), and molecular typing. Common Leptospira serovars with their respective animal hosts were: Sokoine (cattle and rodents); Kenya (rodents and shrews); Mwogolo (rodents); Lora (rodents); Qunjian (rodent); serogroup Grippotyphosa (cattle); and an unknown serogroup from pigs. Inclusion of local serovars particularly serovar Sokoine in MAT revealed a 10-fold increase in leptospirosis prevalence in Tanzania from 1.9 % to 16.9 % in rodents and 0.26% to 10.75 % in humans. This indicates that local serovars are useful for diagnosis of human and animal leptospirosis in Tanzania and neighbouring countries

Using giant African pouched rats to detect tuberculosis in human sputum samples: 2010 findings

Giant African pouched rats previously have detected tuberculosis (TB) in human sputum samples in which the presence of TB was not initially detected by smear microscopy. Operant conditioning principles were used to train these rats to indicate TB-positive samples. In 2010, rats trained in this way evaluated 26,665 sputum samples from 12,329 patients. Microscopy performed at DOTS centers found 1,671 (13.6%) of these patients to be TB-positive. Detection rats identified 716 additional TB-positive patients, a 42.8% increase in new-case detection. These previously unreported data, which extend to over 20,000 the number of patients evaluated by pouched rats in simulated second-line screening, suggest that the rats can be highly valuable in that capacity

Phylogeography and cryptic diversity of the solitary-dwelling silvery mole-rat, genus Heliophobius (family: Bathyergidae)

Alongside the eusocial naked mole-rat, Heterocephalus glaber, Heliophobius argenteocinereus represents the second oldest lineage within the African mole-rat family Bathyergidae, and phylogenetically intermediate between the East African Het. glaber and the South African genera Bathyergus and Georychus. Across its geographic range, Hel.. argenteocinereus is widely distributed on both sides of the East African Rift System (EARS), and is a key taxon for understanding the phylogeographic patterns of divergence of the family as a whole. Phylogenetic analysis of 62 mitochondrial cyt b sequences, representing 48 distinct haplotypes from 26 geographic locations across the range of Heliophobius, consistently and robustly resolved six genetically divergent clades that we recognize as distinct evolutionary species. Early species descriptions of Heliophobius were synonymized into a monotypic taxonomy that recognized only Hel. argentocinereus. These synonyms constitute available names for these rediscovered cryptic lineages, for which combined morphological and genetic evidence for topotypical populations endorses the recognition of six to eight distinct taxa. Bayesian estimates of diver- gence times using the fossil Proheliophobius as a calibration for the molecular clock suggest that the adaptive radiation of the genus began in the early Miocene, and that cladogenesis, represented in the extant species, reflects a strident signa- ture of tectonic activity that forged the principal graben in the EARS.SYNTHESYS grant (BE-TAF-289), grants from the National Research Foundation, the University of Pretoria South Africa (to NCB) and the ERANDA and Bay Foundations (FC).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1469-7998ab201

Mycobacterium tuberculosis volatiles for diagnosis of tuberculosis by Cricetomys rats.

Tuberculosis (TB) diagnosis in regions with limited resources depends on microscopy with insufficient sensitivity. Rapid diagnostic tests of low cost but high sensitivity and specificity are needed for better point-of-care management of TB. Trained African giant pouched rats (Cricetomys sp.) can diagnose pulmonary TB in sputum but the relevant Mycobacterium tuberculosis (Mtb)-specific volatile compounds remain unknown. We investigated the odour volatiles of Mtb detected by rats in reference Mtb, nontuberculous mycobacteria, Nocardia sp., Streptomyces sp., Rhodococcus sp., and other respiratory tract microorganisms spiked into Mtb-negative sputum. Thirteen compounds were specific to Mtb and 13 were shared with other microorganisms. Rats discriminated a blend of Mtb-specific volatiles from individual, and blends of shared, compounds (P = 0.001). The rats' sensitivity for typical TB-positive sputa was 99.15% with 92.23% specificity and 93.14% accuracy. These findings underline the potential of trained Cricetomys rats for rapid TB diagnosis in resource-limited settings, particularly in Africa where Cricetomys rats occur widely and the burden of TB is high

Rapid molecular evolution of pain insensitivity in multiple African rodents

Noxious substances, called algogens, cause pain and are used as defensive weapons by plants and stinging insects. We identified four previously unknown instances of algogen-insensitivity by screening eight African rodent species related to the naked mole-rat with the painful substances capsaicin, acid (hydrogen chloride, pH 3.5), and allyl isothiocyanate (AITC). Using RNA sequencing, we traced the emergence of sequence variants in transduction channels, like transient receptor potential channel TRPA1 and voltage-gated sodium channel Nav1.7, that accompany algogen insensitivity. In addition, the AITC-insensitive highveld mole-rat exhibited overexpression of the leak channel NALCN (sodium leak channel, nonselective), ablating AITC detection by nociceptors. These molecular changes likely rendered highveld mole-rats immune to the stings of the Natal droptail ant. Our study reveals how evolution can be used as a discovery tool to find molecular mechanisms that shut down pain.Grants from the European Research Council (advanced grant 294678 to G.R.L.) and the Deutsche Forschungsgemeinschaft SFB 958 (to G.R.L.), by a South African Research Chair for Mammalian Behavioural Ecology and Physiology to N.C.B., and by a National Science Foundation grant to T.J.P.http://www.sciencemag.orghj2019Mammal Research InstituteZoology and Entomolog

Diagnose der Lungentuberkulose durch Cricetomys gambianus Ratten in Ländern der Armut: Bestimmung der Geruchskomponenten von Mycobacterium Tuberculosis

In Regionen mit geringem Einkommen sind neue Methoden zur Schnelldiagnose der Tuberkulose (TB) dringend erforderlich, auch in Ergänzung zur hauptsächlich genutzten Mikroskopie. Ratten, die speziell auf die Erkennung von TB trainiert wurden, bieten eine vielversprechende Möglichkeit zur schnellen TB-Diagnose gerade in Regionen mit limitierten Ressourcen. Die spezifischen flüchtigen Verbindungen von Mycobacterium tuberculosis (Mtb), die im Sputum von TB Patienten von Cricetomys gambianus Ratten erkannt werden, sind bislang unbekannt. Ebenso ist nicht bekannt, ob diese Ratten Geruchssignale von anderen Mykobakterien und Mtb-ähnlichen Mikroorganismen, welche ebenfalls Lungenerkrankungen auslösen, erkennen. In dieser Arbeit wurden die Mtb-spezifischen flüchtigen Verbindungen untersucht, welche von Ratten erkannt werden. Desweiteren wurde geprüft, ob diese Verbindungen auch von anderen Mykobakterien-Arten abgegeben werden. Dabei wurden klinische Sputen mit verschiedenen Mycobacterium spp, Mtb Genotypen und anderen Mikroorganismen der Atemwege verwendet. Schließlich wurde die Fähigkeit der Ratten untersucht, Mtb-spezifische Verbindungen von anderen verwandten Verbindungen aus Mtb und anderen Mikroorganismen zu unterscheiden. Die Ergebnisse zeigen, dass Mtb spezifisch flüchtige Substanzen bildet, die in anderen Mykobakterien sowie den mykobakterien-ähnlichen Bakterieren Nocardia spp. und Rhodococcus spp. und weiteren Mikroorganismen nicht vorkommen. Die trainierten Ratten nutzen diese flüchtigen Substanzen, um TB-positive Sputen von TB-negativen zu unterscheiden. Flüchtige Verbindungen, die sowohl von Mtb als auch von anderen Mykobakterien produziert werden, ignorieren die Ratten. Ein Gemisch dieser Substanzen wird von den Ratten deutlich besser erkannt, als einzelne Verbindungen. Die Ratten können weiterhin Mtb von anderen Mikroorganismen unterscheiden. Die Detektionsrate wird dabei von der Wachstumphase der Kultur beeinflusst. Die Ratten erkennen schliesslich viel häufiger TB-positive Sputen als negative Sputen, die mit Mtb beimpft bzw. mit den flüchtigen Substanzen versetzt wurden. Klinische Sputen, die Mtb enthalten, werden von den Raten gegenüber Sputen mit anderen Mikroorganismen unterschieden. Sputen, die verschiedene Mtb Genotypen beinhalten, werden ebenso detektiert. Daher ist die Schlussfolgerung zulässig, dass die trainierten Ratten zuverlässig TB erkennen. Weitere Studien sind erforderlich, um die optimalen Bedingungen und Anteile der Mtb-spezifischen flüchtigen Substanzen zu bestimmen, um ähnlich starke Reaktion der Ratten im Vergleich zur Reaktion auf typische TB-positive Sputen zu erhalten. Weitere Untersuchungen sollten die Detektionsrate für Sputen mit häufig vorkommenden nichttuberkulösen Mykobakterien feststellen. Zudem können weitere Untersuchungen, die auch dormante Mtb einschließen, Einblicke in die Ursachen für die Detektion falsch-positiver Sputen geben, die durch Mikroskopie und konventionelle Mtb-Kultur ermittelt wurden, in denen sich dormante Mtb-Erreger nicht anziehen lassen.Novel methods for rapid diagnosis of tuberculosis (TB) are urgently needed to complement the widely used smear microscopy in low income settings. Trained TB detection rats offer a promising tool for rapid diagnosis of TB in resource limited settings. The Mycobacterium tuberculosis (Mtb) specific volatile compounds detected by trained Cricetomys gambianus rats in sputum of TB patients are unknown. It is also not known whether rats detect odour signals from other mycobacteria and microorganisms related to Mtb, which cause pulmonary infections resembling TB. In this thesis I investigated Mtb-specific volatile compounds detected by trained rats and whether the target compounds are found in other mycobacterial species and related pulmonary pathogens. The ability of rats to discriminate cultures of different microorganisms, clinical sputa with different Mycobacterium spp., Mtb genotypes and other respiratory tract microorganisms was investigated. Finally, the ability of the rats to discriminate Mtb-specific odour compounds from shared compounds found in Mtb and other microorganisms was determined. Results show that Mtb produce specific volatile compounds which are not produced by other mycobacterial species, mycobacteria-related Nocardia spp. and Rhodococcus spp. and other microorganisms. Trained rats use these Mtb-specific compounds to distinguish TB-positive sputa from TB-negative sputa. Volatile compounds shared by Mtb and other mycobacteria and non-mycobacterial species are not detected by trained rats. A blend of Mtb-specific compounds is detected by rats better than individual compounds. Rats can discriminate cultures of Mtb from those of other microorganisms. Detection of Mtb cultures is influenced by growth stage. Rats detect more frequently TB-positive sputa than negative sputa spiked with Mtb or specific volatiles. Clinical sputa containing Mtb are well discriminated by rats from sputa containing other microorganisms. Sputa containing different Mtb genotypes are also detected. It is concluded that trained rats can reliably diagnose TB. Further studies are needed to determine the optimal combinations/ratios of Mtb-specific volatile compounds to yield similarly higher responses of rats as those of detection of typical TB-positive sputa. Future studies should assess detection of sputa with frequent nontuberculous mycobacterial species. Further investigations including recovery of dormant Mtb in sputum may give insights on actual cause of detection of false positive sputa currently judged by microscopy and conventional Mtb culture in which dormant Mtb cannot grow