Barbara S. Durrant

• PhD
• San Diego Zoo

Simple Summary Granulosa cells play an essential role in oocyte meiotic competence acquisition by supplying nutrients and metabolites to oocytes and secreting paracrine signals that regulate oocyte maturation. Identifying biomarkers in granulosa cells to measure an oocyte’s ability to mature in vitro noninvasively predicts success or failure prior...

Much remains unknown about the reproductive physiology of southern white rhinoceros (SWR) and the effect of ovarian stimulation prior to ovum pickup (OPU) have not been fully elucidated. Granulosa cells (GC) provide valuable insight into follicle growth and oocyte maturation status. The goals of this study were to evaluate transcriptomic changes in...

Much remains unknown about the reproductive physiology of southern white rhinoceros (SWR) and the effect of ovarian stimulation prior to ovum pickup (OPU) have not been fully elucidated. Granulosa cells (GC) provide valuable insight into follicle growth and oocyte maturation status. The goals of this study were to evaluate transcriptomic changes in...

Efforts to implement effective assisted reproductive technologies (ARTs) for the conservation of the northern white rhinoceros (NWR; Ceratotherium simum cottoni) to prevent its forthcoming extinction, could be supported by research conducted on the closely related southern white rhinoceros (SWR; Ceratotherium simum simum). Within the follicle, extr...

In vivo-collected granulosa cells (GC) from the southern white rhinoceros (SWR) provide a non-invasive assessment of the developmental status of oocytes prior to in vitro culture, which could aid in the development of assisted reproductive technologies (ART). Our study aimed to investigate gene expression in SWR granulosa cells, collected in vivo a...

Context With two northern white rhinos (NWR) remaining, the continued existence of this species relies on studying their relative, the southern white rhino (SWR). Aims (1) Characterise gene expression in granulosa cells (GC) from SWR cumulus oocyte complexes (COCs) prior to (Pre-) and after (Post-) in vitro maturation (IVM), comparing culture medi...

Burmese pythons Python bivittatus captured in the Florida Everglades as part of an invasive species monitoring program served as a model for the development of sperm cryopreservation protocols for endangered snakes. Spermatozoa were collected from the vas deferens and initial motility, plasma membrane integrity and acrosome integrity were recorded...

Anurans can display a host of intriguing sexual syndromes, including hermaphroditism and sex reversal. Using a multifaceted approach for diagnosing and characterising hermaphroditism in the endangered anuran species Rana mucosa, we tracked changes in female reproductive status using hormone monitoring, ultrasound examinations, individual life histo...

Snake populations are declining worldwide, but research devoted to the development of sperm cryopreservation techniques for this taxon is very limited. Spermatozoa were collected postmortem from snakes of four squamate families (Elapidae, Colubridae, Viperidae and Pythonidae). Viability assessment was performed before and after cryopreservation. Sp...

The sloth bear (Melursus ursinus) is one of the least studied bears. Important aspects of sloth bear biology and ecology, such as reproductive physiology and behavior, are largely unknown. Increased scent-marking by anogenital rubbing during breeding season has been recorded in other bear species. We studied the genital rubbing behavior of 37 capti...

The northern white rhino (Ceratotherium simum cottoni) is functionally extinct with only two females left alive. However, cryopreserved material from a number of individuals represents the potential to produce additional individuals using advanced reproductive and genetic rescue technologies and perhaps eventually a population to return to their na...

All extant species in the Rhinocerotidae family are experiencing escalating threats in the wild, making self-sustaining captive populations essential genetic reservoirs for species survival. Assisted reproductive technologies (ARTs) will become increasingly important for achieving and maintaining ex situ population sustainability and genetic divers...

All species in the extant Rhinocerotidae family are experiencing increased threats in the wild, making captive populations essential genetic reservoirs for species survival. However, managed species face distinct challenges in captivity, resulting in populations that are not self-sustaining. Captive southern white rhinoceros (Ceratotherium simum si...

Southern white rhinoceros (SWR) poaching has reached record levels, and captive infertility has rendered SWR assurance populations no longer self-sustaining. Previous work has identified dietary phytoestrogens as a likely cause of this problem. Here, we investigate the role of gut microbiota in this phenomenon by comparing two rhinoceros species to...

In brown kiwi (Apteryx mantelli), the male is the primary incubator, a trait that is relatively rare among birds. The maintenance of avian incubation behavior is controlled by the protein hormone prolactin (PRL). Although steroid hormone concentrations in both wild and captive kiwi have previously been reported, this study is the first to report le...

Vaginoscopy using a 10-mm, 30° forward viewing rigid endoscope was used to evaluate the caudal reproductive tract of four subadult southern white rhinoceros (Ceratotherium simum simum). A vertical vaginal septum was documented in all four animals, including a primiparous cow that gave birth to a stillborn calf 14 months before vaginoscopy. Vaginosc...

The first choice of any captive animal program should be to promote natural breeding through appropriate diet and environmental conditions. However, in cases of poor reproductive performance, the administration of exogenous hormones can induce breeding behaviours and gamete release. Part of the approach to the Mountain yellow-legged frog recovery p...

Cryopreservation of testicular tissue (TT) allows retention of valuable genetic material that can be used for conservation of endangered species, such as the northern white rhinoceros (NWR; Ceratotherium simum cottoni). Previously, we found that cryopreservation of NWR TT with a slow controlled cooling rate (CR) method induced morphological alterat...

The extant Rhinocerotidae family is experiencing threats in the wild, making captive populations important genetic reservoirs for species survival. Because each species faces distinct challenges in captivity, populations are not self-sustaining. Therefore, assisted reproductive technologies (ART) such as AI will be necessary to maintain or increase...

The northern white rhinoceros (NWR; Ceratotherium simum cottoni) is critically endangered. Testicular tissue (TT) of an NWR that died at 46 years was cryopreserved and stored. Spermatogonial stem cells (SSC) have been isolated from TT and, following transplantation or in vitro culture, differentiated into mature spermatozoa. These SSC have been phe...

Once nearly extinct in the wild, the southern white rhinoceros is currently listed as near threatened by IUCN. This status is likely to change as poaching continues to escalate. To preserve the species’ current genetic diversity, cryopreserving and biobanking white rhinoceros sperm is imperative. The horse is the closest domestic relative of the rh...

Animal keepers at zoos and wildlife rescue centers often possess in‐depth knowledge of the health and behavior of the individuals under their care. While it is often not feasible for keepers to regularly collect behavior data through formal scientific methods, efforts should be made to find alternative means to capture this knowledge. We investigat...

With recent poaching of southern white rhinoceros (Ceratotherium simum simum; SWR) reaching record levels, the need for a robust assurance population is urgent. However, the global captive SWR population is not currently self-sustaining due to the reproductive failure of captive-born females. Dietary phytoestrogens have been proposed to play a role...

• Survival of the five remaining rhinoceros species is threatened. Four of the five species are in managed collections, but captive populations are not self‐sustaining and low reproductive rates make population growth slow. • Slow population growth, coupled with behavioural incompatibilities, acyclicity, low genetic diversity, and disease susceptib...

Pregnancy determination is difficult in the giant panda (Ailuropoda melanolecua), representing a challenge for ex situ conservation efforts. Research in other species experiencing pseudopregnancy indicates that urinary/fecal concentrations of 13,14, dihydro-15-keto-prostaglandin F2α (PGFM) can accurately determine pregnancy status. Our objective wa...

Personal communication letter, Dr. Janine Brown. (PDF)

Urinary PGFM giant panda data. (XLSX)

Personal communication letter, Rebecca Snyder. (PDF)

Studies on the reproductive physiology of sloth bears (Melursus ursinus), including the timing and duration of estrous cycles in females, are limited. Normal levels and profiles of estrogen and progesterone in cycling sloth bear females remain largely unknown. A study has been initiated by Wildlife SOS, San Diego Zoo Global, and the Dayalbagh Educa...

The Burmese python (Python bivittatus) is listed as vulnerable by the International Union for Conservation of Nature (IUCN). Released pet Burmese pythons have detrimental effects on fauna native to southern Florida and are responsible for localised declines of several species in some parts of the Everglades National Park (IUCN, 2012; 10.2305/IUCN.U...

Spermatogonial stem cells (SSC) have been isolated from testicular tissue (TT) of several mammalian species and differentiated into mature spermatozoa following transplantation or in vitro culture. The northern white rhinoceros (NWR; Ceratotherium simum cottoni) is critically endangered. Thus, frozen NWR TT, cryopreserved and stored at the San Dieg...

The population of free-roaming white rhinoceroses (Ceratotherium simum) is under serious threat. Captive breeding of this species is therefore becoming more important, but this is challenging and often not successful. Obtaining reproductive reference values is a crucial aspect of improving these breeding results. In this study performed between 200...

Amphibian evolution spans over 350 million years ago, consequently this taxonomic group displays a wide, complex array of physiological adaptations and their diverse modes of reproduction are a prime example. Reproduction can be affected by taxonomy, geographic and altitudinal distribution, and environmental factors. With some exceptions, amphibian...

The captive southern white rhinoceros (SWR) population is not currently self-sustaining due to the reproductive failure of captive-born females. Our research into this phenomenon points to chemicals produced by plants common to captive diets, such as soy and alfalfa, as possible causes. In other species these chemicals, called phytoestrogens, are w...

The ability to successfully fertilize ova relies upon the swimming ability of spermatozoa. Both in humans and in animals, sperm motility has been used as a metric for the viability of semen samples. Recently, several studies have examined the efficacy of low dosage red light exposure for cellular repair and increasing sperm motility. Of prime impor...

The desert tortoise (Gopherus agassizzii) is listed as threatened by the USA Fish and Wildlife Service and population declines continue to occur throughout most of their range. This species’ low reproductive rate, combined with the advanced age at which they reach sexual maturity, makes them vulnerable to multiple threats. Although assisted reprodu...

The North Island Brown Kiwi (Apteryx mantelli) is a nocturnal endangered species endemic to New Zealand. The protection of suitable habitat is key to the species' recovery; however, little is known about their habitat requirements. We studied the diurnal roosting behaviours of kiwis by intensely tracking 41 radio-tagged, non-breeding adults from Ma...

Of the 934 lizard species evaluated by the International Union for the Conservation of Nature (IUCN), at least one-third is threatened with extinction. However, there are no reports of semen cryopreservation efforts for lizards. Invasive Argentine black and white tegus were captured in the Florida Everglades and sperm was collected post-mortem. Ini...

With only three living individuals left on this planet, the northern white rhinoceros (Ceratotherium simum cottoni) could be considered doomed for extinction. It might still be possible, however, to rescue the (sub)species by combining novel stem cell and assisted reproductive technologies. To discuss the various practical options available to us,...

The captive southern white rhinoceros (SWR) population is not currently self-sustaining, primarily due to poor or absent reproduction of captive-born (F1+) females. In this study, we investigate the role of dietary phytoestrogens in this reproductive phenomenon by characterizing activation of SWR estrogen receptors (ESRs) 1 and 2 by diet items from...

Perivitelline membrane (PVM)-bound sperm detection has recently been incorporated into avian breeding programs to assess egg fertility, confirm successful copulation, and to evaluate male reproductive status and pair compatibility. Due to the similarities between avian and chelonian egg structure and development, and because fertility determination...

Severe declines of the mountain yellow-legged frog (MYLF, Rana muscosa) led to establishment of a captive population at the San Diego Zoo Institute for Conservation Research. With less than 200 adults estimated to remain in the wild, the Institute’s MYLF colony currently holds approximately 30% of the entire gene pool. Simulating natural seasonalit...

La extinción de anfibios a nivel global ha conllevado al establecimiento de Programas de Reproducción Internacionales (PRI) como un intento de preservar y reproducir individuos genéticamente valiosos. En el caso de la “Mountain Yellow-legged frog” (Rana muscosa), los PRIs ayudados por tecnologías de reproducción asistida, han ofrecido una única alt...

Recently, CA condors (Gymnogyps californianus) have been reintroduced to coastal regions of California where they feed on marine mammal carcasses. There is evidence that coastal-dwelling condors experience reproductive issues, such as eggshell thinning, likely resulting from exposure to endocrine disrupting chemicals (EDCs). To address this problem...

The success and sustainability of an avian breeding programme depend on managing productive and unproductive pairs. Given that each breeding season can be of immeasurable importance, it is critical to resolve pair fertility issues quickly. Such problems are traditionally diagnosed through behavioural observations, egg lay history and hatch rates, w...

American black bears (Ursus americanus) are seasonally polyoestrous and exhibit delayed implantation, which may allow equal and independent fertility of recurrent oestruses of a mating season. We postulated that the luteal inactivity during delayed implantation allows bears to have sequential ovulation during a polyoestrous mating season such that...

The management of captive avian breeding programs increasingly utilizes various artificial reproductive technologies, including in ovo sexing of embryos to adjust population sex ratios. Currently, however, no attention has been given to the loss of genetic diversity following sex-selective incubation, even with respect to individuals from criticall...

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Only 891 of the approximately 5600 lizard species have been evaluated by the International Union for Conservation of Nature (IUCN). Of those, at least one-third are threatened with extinction. However, there is no organised effort to preserve their genetic diversity through semen banking. As part of an invasive species monitoring program, Argentine...

We examined the potential influences of existing social housing arrangements on captive sun bear female reproductive cycling. Three social conditions were studied: 1.2, 1.1, and 0.2. Fecal hormone metabolites of total estrogens, progestins and glucocorticoids were compared between the three social conditions and were analyzed along with vaginal cyt...

As advanced reproductive technologies have become routine for domesticated species, they have begun to be applied in the field of endangered species conservation. For avian conservation the most promising technology is the transfer of germ stem cells of exotic species to domestic hosts for the production of gametes. In this study, adult quail (mode...

Skewed sex ratios in zoo breeding programs may require housing single birds of an overrepresented gender, increasing demands on limited resources that could otherwise be diverted to breeding pairs or other important species. The ability to selectively incubate and hatch eggs of a desired sex represents a significant improvement in the long-term man...

Fertility determination is an integral part of managing a successful avian conservation program. Assessing breeding potential using noninvasive measures is especially important for endangered species. Detection of avian sperm on the vitelline membrane is a technique used to determine sperm function, sperm/oviduct compatibility and to assess male an...

The incorporation of artificial reproductive technologies, including stem cell rescue, could enhance the reproductive success of an avian breeding/management program. The goal of this research is to produce host chickens capable of generating donor-derived sperm. This could be accomplished by transfer of donor embryo germ stem cells (eGSCs) from ex...

The production of host chickens (Gallus gallus) with chimeric gonads producing gametes derived from transferred exotic donor-bird germ stem cells (GSCs), could potentially have a great impact on the management of threatened species. In this study a novel method of somatic nuclear transfer (snt) was developed using an antibody-biotin-avidin-antibody...

The transfer of adult germ stem cells (GSC) into chicken (Gallus gallus) embryos has the potential to become an important advancement in avian conservation. Many conventional methods of artificial reproductive technologies used in mammals, including cryopreserving oocytes and cloning, can be problematic due to the large size of avian oocytes. Howev...

The increasing number of endangered snake species, isolation of small fragmented populations with associated inbreeding and mating or conception problems in captivity underscore the need to develop assisted reproductive techniques such as semen cryopreservation and artificial insemination to enhance conservation efforts. However, no efficient proto...

The gemsbok is a large antelope native to arid regions of southern Africa. Listed by the International Union for Conservation of Nature as a species of least concern, the gemsbok is an excellent model for the development of assisted reproductive techniques for the closely related but critically endangered scimitar-horned oryx (Oryx dammah) and adda...

The effect of freeze-thaw cycles on the levels of active ceruloplasmin in urine obtained from giant pandas. Repeated freeze-thaw cycles could affect the levels of active ceruloplasmin in urine. Ceruloplasmin activity was decreased by an average of 33, 42, 50, and 53% in the 2nd, 3rd, 4th, and 5th thaws, respectively, compared to the activity observ...

Comparison of active ceruloplasmin values in sample pools of giant panda urine obtained from the change in absorbance/ml enzyme method and standard curve method. To check the validity that the rate of colorimetric change is proportional to the amount of ceruloplasmin in giant panda urine, values obtained from the change in absorbance/ml enzyme calc...

The effects of boiling on the levels of active ceruloplasmin in urine obtained from giant pandas. Change in absorbance in each urine sample was measured prior to boiling and then after boiling for 10 or 30 minutes. Boiling for 10 minutes produced a decrease in activity by an average of 34%, while boiling for 30 minutes produced a decrease in activi...

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After ovulation, non-pregnant female giant pandas experience pseudopregnancy. During pseudopregnancy, non-pregnant females exhibit physiological and behavioral changes similar to pregnancy. Monitoring hormonal patterns that are usually different in pregnant mammals are not effective at determining pregnancy status in many animals that undergo pseud...

Optical trapping is a noninvasive biophotonic tool that has been developed to study the physiological and biomechanical properties of cells. The custom‐designed optical system is built to direct near‐infrared laser light into an inverted microscope to create a single‐point three‐dimensional gradient laser trap at the microscope focal point. A real‐...

Conservation of germplasm from endangered species is a priority for all classes of animals. However, the large avian oocyte and the inability to consistently superovulate birds make techniques such as cloning and oocyte cryopreservation unlikely tools for avian conservation. Instead, the use of domestic birds as hosts to produce sperm of exotic spe...

We investigated the potential use of leptin as a wildlife management tool to monitor adiposity in American black bears (Ursus americanus). Body mass (BM), body condition index (BCI), serum leptin concentration, and percent of body fat were measured in semi-free ranging (SFR) adult male (South Dakota, Oct 2003–Jun 2004) and free-ranging (FR) adult f...

Precise determination of the time of ovulation will greatly enhance the success rate of artificial insemination and timed breedings of captive marine mammals. Because daily samples are necessary to effectively monitor the estrous cycle, behavioral conditioning of blood and urine collection has greatly facilitated the development of reproductive hor...

Interspecific (xeno) transfer of embryonic primordial germ cells (PGCs) from quail (Coturnix japonica) to chicken (Gallus gallus) has produced germ cell chimeras that generate viable donor-derived germ cells. The practical application of this technique for the preservation of endangered species requires the use of gonadal stem cells (GSCs) recovere...

Conservation of germplasm from endangered and genetically valuable individuals is a high priority for all classes of animals. However, the large avian oocyte and the inability to consistently super ovulate birds make techniques such as cloning and oocyte cryopreservation unlikely tools for avian conservation. Instead, the use of domestic birds as h...

The combination of laser tweezers, fluorescent imaging, and real-time automated tracking and trapping (RATTS) can measure sperm swimming speed and swimming force simultaneously with mitochondrial membrane potential (MMP). This approach is used to study the roles of two sources of ATP in sperm motility: oxidative phosphorylation, which occurs in the...

Artificial insemination (AI) is the least invasive assisted reproductive technology, and is therefore of great interest to breeders of companion animals, non-domestic, and endangered species (CANDES). This most fundamental artificial breeding technique circumvents physical or behavioral impediments to natural mating and provides the means for genet...

We report the isolation and characterization of eight polymorphic and five monomorphic microsatellites in North Island brown kiwi (NIBK, Apteryx mantelli), using two polymerase chain reaction (PCR) techniques employing either short-tandem repeat primers (STR method) or random PCR-based isolation of microsatellite arrays (PIMA method). Microsatellit...

We combine laser tweezers with custom computer tracking software and robotics to analyze the motility [swimming speed, VCL (curvilinear velocity), and swimming force in terms of escape laser power (Pesc)] and energetics [mitochondrial membrane potential (MP)] of individual sperm. Domestic dog sperm are labeled with a cationic fluorescent probe, DiO...

Gonadal stemcells are capable of producing an endless supply of germcells during the reproductive lifespan of an individual. Collection of these stemcells from gonads during necropsy has the potential to be a very powerful tool for conservation of avian species. Successful transfer and development of donor gonadal stemcells in a host gonad will all...

Of the eight species of Ursidae, six are currently at risk of extinction and the remainder face significant risks to their future survival. One of the greatest threats to bears is human‐imposed environmental alteration (e.g. global warming, chemical pollutants, deforestation). An examination of the reproductive biology and phylogeny of the Ursidae...