99 research outputs found
Parentage analysis in a managed free ranging population of southern white rhinoceros : genetic diversity, pedigrees and management
Small populations are vulnerable to the consequences of breeding within closed groups as the loss of genetic variability can lead to inbreeding depression. Here, we use microsatellite genotypes to assess variability and parentage within a small, managed population of southern white rhinoceros in northern Namibia. Tissue samples gathered from either a modified biopsy darting technique or ear notches allowed us to obtain genotypic data for all individuals in the population. As expected for this species, genetic variability in the population was relatively low (overall H obs 0.45). In combination with detailed management records for the period 1993–2009, we were able to assign both parents for all 23 offspring. Only one calf of seven in the F2 generation arose from father–daughter inbreeding within the population. Our analysis revealed that paternity was initially dominated by a single founder bull siring 10 of 13 calves over 9 years; paradoxically, the other founder bull was selected for removal based on observations suggesting he was behaviourally dominant and therefore the likely sire of most calves. We also found that young introduced bulls were breeding successfully within 6 months of their arrival, well before having established their home ranges. We argue that in order to optimally manage and conserve the southern African white rhinoceros meta-population it is essential to have accurate pedigree information and genetic data for all individuals in the numerous small populations that are key to the survival of the species.Ongava Research Centre is funded by charitable donations from the Namibian Wildlife Conservation Trust (UK), West Midlands Safari Park (UK) and the Directors of Ongava Game Reserve.http://link.springer.com/journal/10592hb201
Dynamics of gelling liquids: a short survey
The dynamics of randomly crosslinked liquids is addressed via a Rouse- and a
Zimm-type model with crosslink statistics taken either from bond percolation or
Erdoes-Renyi random graphs. While the Rouse-type model isolates the effects of
the random connectivity on the dynamics of molecular clusters, the Zimm-type
model also accounts for hydrodynamic interactions on a preaveraged level. The
incoherent intermediate scattering function is computed in thermal equilibrium,
its critical behaviour near the sol-gel transition is analysed and related to
the scaling of cluster diffusion constants at the critical point. Second,
non-equilibrium dynamics is studied by looking at stress relaxation in a simple
shear flow. Anomalous stress relaxation and critical rheological properties are
derived. Some of the results contradict long-standing scaling arguments, which
are shown to be flawed by inconsistencies.Comment: 21 pages, 3 figures; Dedicated to Lothar Schaefer on the occasion of
his 60th birthday; Changes: added comments on the gel phase and some
reference
Colloid/nanoparticle formation and mobility in the context of deep geological nuclear waste disposal (project KOLLORADO-1; final report)
Ultrasonographic and laparoscopic evaluation of the reproductive tract in older captive female cheetahs (Acinonyx jubatus)
The study uniquely described the clinical value of transabdominal ultrasonography for
monitoring features characterizing the estrous cycle in female cheetahs (Acinonyx jubatus). The
reproductive tracts of 21 female, nulliparous, and relatively aged (median: 11 and interquartile
range: 9.25–14 years) captive cheetahs resident on two sites in Namibia were assessed by
transabdominal ultrasound. Subsequently, the ovarian findings on ultrasound were compared
with direct visualization while performing laparoscopic sterilization. A combination of these
observations supported by concurrent sampling for vaginal cytology and serum progesterone
concentrations defined the estrous status of individual animals. At one site, six cheetahs had
been implanted with the GnRH agonist, deslorelin as a contraceptive at least once within the
preceding 11 years. On ultrasound, 31 uterine horns and 35 ovaries with discernible structures
on 28 (86%) were visualized in the 21 cheetahs. The uterine body was difficult to visualize
because of its intrapelvic location. Eleven of 19 uteri (58%) visualized showed endometrial
edema suggestive of estrogenization. The uteri of four cheetahs (19%) showed evidence of mild
cystic endometrial hyperplasia. Paraovarian cysts were seen on ultrasound (n ¼ 21) and laparoscopy
(n ¼ 26) in 16 (76.2%) and 18 (85.7%) cheetahs, respectively. Ovarian volumes obtained
from ultrasonographically determined dimensions predicted cyclic activity.
Laparoscopy showed that 19 ovaries had discernible follicular structures. In the study population,
10 (47.6%) cheetahswere in proestrus or estrus; none in the luteal phase; and 11 (52.4%)
in anestrus. Transabdominal ultrasound, in combination with serum progesterone concentrations
and vaginal cytology, was used with acceptable accuracy to assess cyclic ovarian activity
in captive cheetahs. A considerable proportion of this aged population showed ovarian
activity and the prevalence of paraovarian cysts was notable. A history of prior deslorelin
treatment was not associated with either reproductive activity or uterine pathology.AfriCat Foundation and CCF in Namibia.http://www.theriojournal.com2016-12-31hb2015ab201
Single-incision laparoscopic sterilization of the cheetah (Acinonyx jubatus)
OBJECTIVE : To describe laparoscopic ovariectomy and salpingectomy in the cheetah (Acinonyx jubatus) using single-incision
laparoscopic surgery (SILS).
STUDY DESIGN : Prospective cohort.
ANIMALS : Female cheetahs (Acinonyx jubatus) ( n ¼ 21).
METHODS : Cheetahs were randomly divided to receive either ovariectomy (n ¼ 11) or salpingectomy (n ¼ 10). The use and
complications of a SILS port was evaluated in all of cheetahs. Surgery duration and insufflation volumes of carbon dioxide
(CO2) were recorded and compared across procedures.
RESULTS : Laparoscopic ovariectomy and salpingectomy were performed without complications using a SILS port. The
poorly-developed mesosalpinx and ovarian bursa facilitated access to the uterine tube for salpingectomy in the cheetah. The
median surgery duration for ovariectomy was 24 minutes (interquartile range 3) and for salpingectomy was 19.5 minutes
(interquartile range 3) (P ¼.005). The median volume of CO2 used for ovariectomy was 11.25 L (interquartile range
3.08) and for salpingectomy was 4.90 L (interquartile range 2.52), (P ¼.001)
CONCLUSIONS : Laparoscopic ovariectomy and salpingectomy can be performed in the cheetah using SILS without perioperative
complications. Salpingectomy is faster than ovariectomy and requires less total CO2 for insufflation.NRF grants, AfriCat. Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa and the Arabella Dean
fund of the South African Veterinary Foundation.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1532-950X2016-07-30hb2015ab201
Ultra-Fast Oleophobic-Hydrophilic Switching Surfaces for Anti-Fogging, Self-Cleaning, and Oil-Water Separation
Smooth copolymer–fluorosurfactant complex film surfaces are found to exhibit fast oleophobic–hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80°) and low water contact angle (110°), which, when combined with the inherent ultrafast switching speed, yields oil–water mixture separation efficiencies exceeding 98%
Phylogenetic tree derived from bacterial, cytosol and organelle 5S rRNA sequences.
A phylogenetic tree was constructed by computer analysis of 47 completely determined 5S rRNA sequences. The wheat mitochondrial sequence is significantly more related to prokaryotic than to eukaryotic sequences, and its affinity to that of the thermophilic Gram-negative bacterium Thermus aquaticus is comparable to the affinity between Anacystis nidulans and chloroplastic sequences. This strongly supports the idea of an endosymbiotic origin of plant mitochondria. A comparison of the plant cytosol and chloroplast sub-trees suggests a similar rate of nucleotide substitution in nuclear genes and chloroplastic genes. Other features of the tree are a common precursor of protozoa and metazoa, which appears to be more related to the fungal than to the plant protosequence, and an early divergence of the archebacterial sequence (Halobacterium cutirubrum) from the prokaryotic branch
Diffusion of gelation clusters in the Zimm model
Starting from a Zimm model, we study self-diffusion in a solution of crosslinked monomers. We focus on the effects of the hydrodynamic interaction on the dynamics and the critical behaviour at the sol-gel point. Hydrodynamic interactions cause the clusters’ diffusion constant to depend not only on the cluster’s size but also on the cluster’s shape --in contrast to the Rouse model. This gives rise to a non-trivial scaling of the Kirkwood diffusion constant averaged over all clusters of fixed size n, with given in terms of the spectral dimension of critical percolation clusters. The long-time decay of the incoherent scattering function is determined by the diffusive motion of the largest clusters. This implies the critical vanishing of the cluster-averaged effective diffusion constant at the gel point with exponent
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