Effect of four eggshell repair materials on weight loss during incubation of white leghorn chicken eggs

Egg weight loss during incubation is a key indicator used to monitor successful egg development and is closely related to hatchability and chick survival. Artificial incubation is one of the most important captive breeding techniques used in conservation efforts to bolster avian populations. To repair damage to the eggshell and ensure embryonic viability during incubation, a variety of repair coverings can be applied. This study tested the impact of four repair materials (nail polish, synthetic glue, medical dressing, and molten wax film) on egg weight loss during incubation. We found no impact on weight loss for coverings smaller than 35% of the eggshell surface, nor did we find any differences between covering types. The average egg weight loss decreased as the coverage area increased, and the weight loss did not differ when blunt versus sharp-end coverings were compared. Given the relative insensitivity of egg weight loss and survival to the type of patch material used, we concluded that the selection of material for the purpose of weight loss management could be based on practical considerations, such as ease of application and availability.

Glucose consumption and gene expression in granulosa cells collected before and after in vitro oocyte maturation in the southern white rhinoceros (Ceratotherium simum simum)

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 media and oocytes from donors treated with or without gonadotropin stimulation prior to ovum recovery; and (2) evaluate COC glucose consumption in spent media.

METHODS

COCs were retrieved from four SWRs. Granulosa cells were collected before and after IVM in SDZ or IZW medium. Total RNA was evaluated by qPCR.

KEY RESULTS

Oocyte maturation was greater in SDZ than IZW media. Expression of genes associated with follicle development increased in Pre-IVM GC. Six genes were differentially expressed in Post-IVM GC from stimulated compared to unstimulated donors. COCs from stimulated animals consumed more glucose. Fifty seven percent of oocytes in SDZ medium consumed all available glucose.

CONCLUSIONS

Gene expression changed upon in vitro maturation and gonadotropin stimulation. Higher glucose availability might be needed during IVM.

IMPLICATIONS

This is the first study examining GC gene expression and COC metabolic requirements in rhinoceros, which are critical aspects to optimise IVM of rhinoceros oocytes.

Use of Bisection to Reduce Mitochondrial DNA in the Bovine Oocyte

Interspecies somatic cell nuclear transfer (iSCNT) may be used to rescue endangered species, but two distinct populations of mitochondrial DNA (mtDNA) exist within the reconstructed embryo: one within the recipient ooplasm and one within the donor somatic cell. This mitochondrial heteroplasmy can lead to developmental issues in the embryo and the fetus. Handmade cloning protocols include oocyte bisection, which can be used to decrease the mtDNA copy number, reducing the degree of mitochondrial heteroplasmy in a reconstructed embryo. Centrifugation of denuded, mature bovine oocytes produced a visible mitochondria-dense fraction at one pole of the oocyte. Oocytes' zonae pellucidae were removed by exposure to a pronase solution. Bisection was performed using a microblade to remove the visible mitochondria fraction. qPCR was used to quantify the mtDNA present in DNA samples extracted from whole oocytes and bisected ooplasts, providing a comparison of mtDNA copy numbers before and after bisection. Copy numbers were calculated using cycle threshold values, a standard curve's regression line formula, and a ratio that included the respective sizes of mtDNA PCR products and genomic PCR products. One bovine oocyte had an average mtDNA copy number (± standard deviation) of 137,904 ± 94,768 (n = 38). One mitochondria-depleted ooplast had an average mtDNA copy number of 8,442 ± 13,806 (n = 33). Average mtDNA copies present in a mitochondria-rich ooplast were 79,390 ± 58,526 mtDNA copies (n = 28). The differences between these calculated averages indicate that the centrifugation and subsequent bisection can significantly decrease the mtDNA copy numbers present in the mitochondria-depleted ooplast when compared to the original oocyte (P < 0.0001, determined by one-way ANOVA). The reduction in mtDNA should decrease the degree of mitochondrial heteroplasmy in a reconstructed embryo, possibly fostering standard embryonic and fetal development. Supplementation with mitochondrial extract from the somatic donor cell may also be essential to achieve successful embryonic development.

Sperm cryopreservation in the Burmese python Python bivittatus as a model for endangered snakes

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 before cryopreservation. Spermatozoa were extended in TES and Tris (TEST) yolk buffer with glycerol (GLY) or dimethyl sulfoxide (DMSO) concentrations of 8%, 12% or 16%, or combinations of GLY and DMSO with final concentrations of 4%:4%, 6%:6% or 8%:8%, and frozen at a rate of 0.3°C min-1. Sperm frozen in combinations of GLY and DMSO exhibited greater post-thaw motility and plasma membrane integrity than those frozen in GLY or DMSO alone. All DMSO and GLY:DMSO treatments preserved a greater proportion of intact acrosomes than GLY alone. To determine the best overall cryopreservation protocol for this species, a sperm quality index was calculated, giving equal weight to each of the three measured indicators of cryosurvival. This analysis revealed that Burmese python spermatozoa frozen in 6% GLY:6% DMSO or 4% GLY:4% DMSO exhibited the highest post-thaw viability. This study represents the first comparative, comprehensive attempt to develop a sperm cryopreservation protocol for any snake species.

Challenges in the development of sperm cryopreservation protocols for snakes

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. Spermatozoa were extended in TES and Tris (TEST) yolk buffer with 12% dimethylsulfoxide (DMSO) or 12% glycerol and frozen at a rate of 0.3°Cmin-1 . The sperm quality index (SQI), representing three viability parameters (motility, plasma membrane and acrosome integrity), was determined. Despite some species differences, glycerol was a more effective cryoprotectant for Colubridae, whereas DMSO provided greater cryoprotection for spermatozoa of members of the other three families.

Serum prolactin and testosterone levels in captive and wild brown kiwi (Apteryx mantelli) during the prebreeding, breeding, and incubation periods

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 levels of PRL in captive and wild male and female kiwi through the prebreeding and breeding seasons, and to directly compare testosterone (T) concentrations between captive and wild males during the breeding and incubation periods. Female PRL concentrations increased at the time of oviposition, whereas male PRL concentrations rose gradually between the prebreeding and incubation periods. Although males are considered the main incubator, an increase in PRL levels could help females maintain behaviors such as nest guarding, or to take over incubation the event of mate loss. A gradual increase in PRL allows the male to be ready for incubation during the long breeding season. Interestingly, T concentrations in captive males did not decrease during incubation and was significantly higher than in wild males. Continual elevated T could have an impact on sperm production through negative feedback, thereby contributing to the low egg fertility seen in captive kiwi. Therefore, determining the underlying reason for the differences in hormone levels could be significant, if not vital, for improving the success of captive kiwi breeding programs.

98 Efficacy of commercial equine semen freezing extenders for cryopreservation of southern white rhinoceros (Ceratotherium simum simum) sperm

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 rhinoceros and a useful model for the development of assisted reproductive technologies, including semen cryopreservation. Two equine semen cryopreservation protocols were compared to a common rhinoceros freezing method. Semen was collected from a single male on 3 occasions by electroejaculation. Initial semen parameters were 86% motility; speed 3.2 (scale 1-5); 89% plasma membrane integrity; and 95% intact acrosomes. Semen was extended 1:1 in INRA 96 (IMV Technologies, L’Aigle, France) before centrifugation at 400×g for 10min. Supernatant was removed and the sperm pellet was subjected to 1 of 2 treatments: resuspension in 500µL of either BotuCrio (Botupharma, Botucatu, Brazil) or Cryomax (ARS Inc., Chino, CA, USA), both containing a proprietary combination of glycerol and an amide as cryoprotectants. Following a 40-min cool at 4°C, extended semen was frozen in vials at a cooling rate of 30°C/min for 3min before LN submersion. Control semen was extended 1:1 in TEST-Y buffer without cryoprotectant and cooled for 2.5h before adding glycerol to a final concentration of 4%. Extended sperm (500µL) was frozen in vials at 12.5°C/min for 15min before LN submersion. Initial motility score (IMS;% motile×speed of progression2), plasma membrane integrity (IPL), and acrosome integrity (IAC) were recorded after extension. All vials were thawed at 37°C for 60s and the cryoprotectant was removed by centrifugation. Sperm pellets were resupended in M199+HEPES and sperm was evaluated for the characteristics described above at 37°C at 0, 30, and 60min (T0, T30, T60) post-thaw. All data are expressed as a percentage of initial (%IMS,%IPL, and%IAC) to account for the differences in sperm parameters between ejaculates. Cryopreservation protocol significantly affected%IMS at T0 (P=0.0131, Table 1). Although the differences were significant only at T0, sperm frozen in Botucrio or Cryomax tended to maintain a higher%IMS than the control freeze at all time points. However, sperm frozen in Cryomax lost a greater percentage of%IMS over time (67% from T0 to T60v. 44 and 46% for Botucrio and TEST-Y, respectively). Cryopreservation protocol did not affect%IAC or%IPL at any time point, but again Cryomax and Botucrio tended to be higher than TEST-Y. This study indicates that rhinoceros sperm may suffer less cryodamage in Botucrio or Cryomax frozen at 30°C/min than in the conventional TEST-Y frozen at 12.5°C/min. Table 1.Percent of initial motility score (IMS), plasma membrane integrity (IPL), and acrosome integrity (IAC) at 0, 30, and 60min post-thaw (T0, T30, and T60, respectively)

103 Hormonal stimulation and post-breeding sperm induction in the mountain yellow-legged frog, Rana muscosa

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 program is the collection of sperm for cryobanking as a means of preserving genetic diversity in a cost- and space-effective manner. To develop a protocol for induction of sperm release from Mountain yellow-legged frogs, we tested the administration of gonadotropin-releasing hormone agonist (d-Ala6, des-Gly10 ethylamide LHRH derivative) and hCG singly or in combination. Once a month, animals were injected with a single dose of saline amphibian ringers (control) or 1 of 10 hormone treatments. Groups 1-4 received a single intraperitoneal injection of gonadotropin-releasing hormone agonist administered in 4 different doses: (1) 0.3 μg/g body weight (bw); (2) 0.4 μg/g bw; (3) 0.6 μg/g bw; and (4) 1 μg/g bw. Groups 5 and 6 were injected with 5 and 10IU hCG/g bw, respectively, and groups 7-10 received a combined injection of hCG and GnRH in four different doses: (7) 5 IU/g hCG with 0.3 μg/g GnRH; (8) 10 IU/g hCG with 0.3 μg/g GnRH; (9) 5 IU/g hCG and 0.6 μg/g GnRH; and (10) 10 IU/g hCG and 0.6 μg/g GnRH. Hormone treatments began in July 2015, 2 months after the end of the breeding season to allow males a post-breeding recovery time. Monthly administration continued from July until December 2015, ending before the brumation period. In 2016, treatments resumed again in July, after another breeding period. In 2017, hormone treatments began in April, during the reproductive season, and continued until July. From July 2015 through November 2016, sperm concentration and motility were examined in response to hormones treatment groups 1, 3, 5, 6, and 7-10. In April 2017, based on previous results, experiments were redesigned to include group 9 from 2015-16, and two new groups, 2 and 4. Spermiation was not easily hormonally induced when administered from August-October 2015, August-September 2016, and in July 2017. These low-response periods coincided with post-breeding months when only 3.7% (3/81) of males responded to either 10 IU/g hCG, 0.6 μg/g GnRH, or a combination of 5 IU/g hCG and 0.6 μg/g GnRH. Sperm production was significantly affected (P&lt;0.05) by the month of hormone administration and hormone treatments during the responsive periods (P&lt;0.0001) of April-June and October-November. However, hormone doses and treatments had no significant effect on the average or total sperm concentration per male (P&lt;0.05). Motility and speed of forward progression were not significantly affected by treatment (P&lt;0.05). This study demonstrates the seasonality of sperm production in this species, which may be attributed to testicular recrudescence during the summer months following breeding. Without hormonal stimulation, spermiation did not occur during the nonreproductive part of the year.

97 Ovulation induction in anovulatory southern white rhinoceros (Ceratotherium simum simum)

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 captive genetic variation. Captive-born female white rhinoceros (Ceratotherium simum simum) have low reproductive rates and apparent acyclicity is a common issue. Although females fail to ovulate and progesterone remains at baseline levels, follicle growth may occur and ovulation can be induced with exogenous hormones. Female southern white rhinos (n=6) housed as a bachelorette group were determined to be ovulatory (n=1) or anovulatory (n=5) by serial ultrasound and fecal progesterone (P4; ng g−1) analysis. However, all anovulatory females grew follicles beyond preovulatory size, which then regressed. At the time of study, when follicles were preovulatory size (35.4±1.2 mm; mean±SD), anovulatory females (n=4) were induced to ovulate (n=11) with a gonadotropin releasing hormone (GnRH) agonist (4.5mg, SucroMate™; Bioniche Animal Health, Bogart, GA, USA) in a single intramuscular injection. Nine treatments resulted in ovulation (81.8%), all between 36 and 48h post-treatment, while 2 hemorrhagic anovulatory follicles (18.2%; HAF) formed, both in the same female. Ovulations were confirmed by disappearance of the follicle by 48h and P4 elevation above baseline was coincident with corpus luteum (CL) and HAF formation. All resulting luteal structures were included in analysis. Follicle growth was permitted to proceed without GnRH treatment between inductions (n=6); dominant follicles grew beyond preovulatory size (43.8±6.1mm) followed by regression and growth of another preovulatory follicle that was subjected to GnRH treatment. Data were analyzed by R studio (ver. 1.1.383). Luteal phases were characterized as “short” (&lt;50 days) or “long” (&gt;50 days). Only P4 above baseline (days) was significantly different (P&lt;0.05) between long and short cycles. Other cycle parameters, such as CL visibility (days), time from ovulation to P4 above baseline (days), maximum P4 (ng g−1), and maximum luteal size (mm), were not significantly different between cycle types. Both cycle types were observed following both spontaneous (short, n=5; long, n=3) and induced ovulations (short, n=8; long, n=3). These data provide additional insight into the differences between long and short cycles and that GnRH is a reliable and effective method to overcome anovulation in SWR. We also prove that long cycle lengths are not necessarily indicative of early pregnancy loss, as has been previously suggested. Taken together, this information can enhance captive breeding efforts and the genetic diversity of the ex situ, SWR insurance population.

25 Cryopreservation of horse testicular tissue as a model for rhinoceros

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 alterations in the seminiferous tubules (ST). However, the relative influence of CR, type of medium, and condition of TT from the aged NWR male on TT integrity was not clear. Due to the limited availability of rhinoceros TT, we used the horse as a model for optimization of TT cryopreservation. We evaluated the effect of (1) cryoprotectant solution [PBS (PBS +1.5M dimethyl sulfoxide) v. DMEM (DMEM/F12+10.0% fetal bovine serum+0.05M sucrose+1.5M dimethyl sulfoxide)] and (2) CR [CR1 (−2.0°C min−1 from 0°C to −4.0°C, −15°C min−1 to −12°C, and −0.3°C min−1 to −40°C in a programmable freezer) v. CR2 (same as CR1 but cooled to −8°C and held for 5min before cooling to −40°C) v. CR3 (−1.0°C min−1 from 0°C to −80°C in a CoolCell® freezing device; Corning, Corning, NY, USA)] on the structural integrity of ST from a 2-year-old horse (n=20 ST), cell viability, and expression of spermatogonial stem cells (SSC; GFRα1, and GRP125) and pluripotent markers (SSEA-4, SSEA-1, and OCT-4) in spermatogonial cells isolated from TT frozen with the above treatments (n=3). We found a positive interaction between CR and cryoprotectant solution on structural integrity of fixed and stained TT after freezing in PBS and CR2 that resulted in lower detachment of epithelium cells from the basement membrane (score±standard error of the mean; 0.50±0.1) than that of TT frozen in PBS and CR1 and CR3 (1.00±0.1 and 1.80±0.1, respectively; P&lt;0.001) or in DMEM and CR1 (1.25±0.1), CR2 (1.35±0.1), and CR3 (1.40±0.1; P&lt;0.01) and in lower incidence of basement membrane damage (0.75±0.1) than that of TT frozen in PBS and CR1 (1.17±0.07) and CR3 (1.16±0.07) or in DMEM and CR1 (1.10±0.1), CR2 (1.15±0.1), or CR3 (1.45±0.1; P&lt;0.01). A lower rate of pyknosis was observed in TT frozen with PBS (1.15±0.06) than in TT frozen in DMEM (1.43±0.06; P&lt;0.001). Overall, integrity of ST was improved when TT was frozen in PBS at CR2 having similar percentages of ST with intact epithelium (60%) and basement membrane (35%) as that of refrigerated TT (45 and 50%, respectively) but different from that of TT frozen with PBS at CR1 (10 and 15%, respectively; P&lt;0.05). Flow cytometry analysis of spermatogonial cells revealed that the percentages of live cells from TT frozen in PBS (CR1: 61.5±7.4%; CR2: 59.7±4.8%; CR3: 51.5±4.1%) or DMEM (CR1: 66.2±6.0%; CR2: 59.8±6.0%; CR3: 58.9±6.9%), and expression of SSC and pluripotent markers was similar among all freezing treatments. However, the percentages of live cells from frozen-thawed TT were lower than those of cells isolated from refrigerated TT (80.6±2.2%; P&lt;0.001). Overall, our results showed that (1) structural integrity of horse ST was better maintained when TT was frozen in PBS at CR2 and (2) SSC can be isolated from frozen-thawed TT with a similar relative frequency to that of refrigerated TT.

189 Isolation and purification of rhinoceros and horse spermatogonial stem cells

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 phenotypically characterised by the expression of markers specific for SSC, and in vitro culture methods optimized to isolate, purify, and enrich populations of SSC from mixed germ cells. The reproductive age may affect the percent of SSC in TT, affecting recovery from older animals. We previously identified in TT of NWR the surface markers GFRa1 and GPR125, both of which were expressed at various stages of spermatogenesis. However, characterisation, isolation, and purification of rhinoceros SSC have not been studied. Because of the limited availability of rhinoceros TT, we used the horse as a model for rhinoceros (both species are in the same order: Perissodactyla). In this study, we (1) identified and compared the expression of markers specific for SSC (GFRa1, GPR125, PLZF) and pluripotent markers (SSEA-1, SSEA-4, OCT-4) in rhinoceros and horse mixed germ cells; (2) evaluated whether rhinoceros and horse SSC could be purified and enriched by sequential culture with collagen (2 days) and laminin (3 weeks); and (3) determined whether age may affect the percentages of SSC by comparing the expression of SSC and pluripotent markers in horse mixed germ cells at different reproductive stages: pubertal (PU=1-1.5 years) v. post-pubertal (PP=2-3 years) v. adult (AD=&gt;5 years). Mixed germ cells were isolated from testes of one male of each of 3 rhinoceros species: NWR, southern white rhinoceros (SWR; Ceratotherium simum simum, 49 years), and greater one-horned rhinoceros (GOHR; Rhinoceros unicornis, 5 years), and horses at different reproductive stages (PU=2, PP=2, AD=7). The SWR and GOHR testes were refrigerated overnight, whereas NWR mixed germ cells were isolated from frozen-thawed TT. Flow cytometry analysis showed expression of SSC and pluripotent markers but not for transcription factor PLZF. The marker expression was similarly distributed between the 3 species of rhinoceros, with a larger portion of cells positive for SSEA-4 (mean%±s.e.m.: 6.3±1.1%) and smaller proportion for GDNFa1 (0.4±0.2%), GRP125 (0.1±0.1%), OCT-4 (0.4±0.2%), and SSEA-1 (0.4±0.2%; P&lt;0.05). Similarly, horse expressed the markers GDNFa1 (0.9±0.3%), GRP125 (0.9±0.4%), OCT-4 (1.7±0.5%), and SSEA-1 (0.12±0.1%), but the abundance of SSEA-4 (1.8±0.8%) was less than that of rhinoceros (P&lt;0.05). In rhinoceros, sequential culture enhanced the numbers of cells expressing all markers compared with that before culture, whereas in horses, the increase was observed only for cells expressing GDNFa1, GPR125, and SSEA-1. Reproductive stage did not affect the percentages of horse cells expressing germ cell and pluripotent markers. Overall, these results showed that rhinoceros SSC can be isolated from TT and expressed the same SSC markers as horses, and that differential culture enriched a population of SSC.

92 Sperm Cryopreservation in the Burmese Python (Python bivittatus) as a Model for Endangered Snakes

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.UK.2012-1.RLTS.T193451A2237271.en). As part of an invasive species monitoring program, Burmese pythons were captured in the Florida Everglades and used as a model for the development of sperm cryopreservation protocols for endangered snakes. Sperm was collected by flushing the vas deferens postmortem and initial motility score (IMS; % motile × speed of progression2), plasma membrane integrity (IPL), and acrosome integrity (IAC) were recorded before cryopreservation. Sperm was extended in TEST-yolk buffer with final dimethyl sulfoxide (DMSO) or glycerol (GLY) concentrations of 8, 12, or 16%, or combinations of DMSO and GLY with final concentrations of 4:4, 6:6, or 8:8%. Sperm in 500 µL of extender was frozen in vials at 0.3°C/min to –40°C before storage in liquid nitrogen. For each treatment, triplicate vials from each of 3 males were thawed at 37°C for 90 s. Cryoprotectant was removed by centrifugation and the sperm pellet was resuspended in TCM-199+HEPES. Sperm was evaluated at 22°C immediately following resuspension (T0) and at 60 (T60) minutes. All data were expressed as a percentage of initial (%IMS, %IPL, and %IAC). The effects of freeze method on %IMS, %IPL and %IAC were analysed by ANOVA and Tukey’s HSD test. Freeze method significantly affected %IMS at T0 (P = 0.0004) and T60 (P = 0.0001), with sperm frozen in the 6%DMSO:6%GLY and 4%DMSO:4%GLY treatments resulting in the highest %IMS at both T0 (19.4% and 17.7%, respectively) and T60 (26.7% and 14.4%, respectively). Regardless of cryoprotectant concentrations, sperm frozen in a combination of DMSO and GLY exhibited significantly higher %IMS than all treatments of DMSO or GLY alone (P < 0.0001 at T0 and T60). The %IPL was significantly affected by freeze method at T0 (P < 0.0001) and T60 (P = 0.0266). Sperm frozen in 8%DMSO:8%GLY and 6%DMSO:6%GLY retained greater %IPL at both T0 (69.1% and 65.7%, respectively) and T60 (47.8% and 49.9%, respectively). Acrosome integrity was significantly affected by freeze method at T0 (P < 0.0001) and sperm frozen in 8% DMSO resulted in the greatest %IAC (56.4%). In addition, all DMSO and DMSO:GLY treatments preserved a significantly greater proportion of intact acrosomes than GLY alone (P < 0.0001). To simplify these analyses and to determine the best overall freeze method for this species, a sperm quality index (SQI) was calculated, giving equal weight to each of the 3 measured indicators of cryosurvival. The SQI analysis revealed that Burmese python sperm frozen at 0.3°C/min in either 6%DMSO:6%GLY or 4%DMSO:4%GLY exhibited significantly higher post-thaw viability at T0 and T60 than all other treatments. This study represents the first comparative, comprehensive attempt to develop a sperm cryopreservation protocol for any snake species.

187 Morphological Appearance and Expression of Spermatogonial Stem Cell Markers in White Rhinoceros Testicular Tissue

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 Diego Zoo’s Frozen Zoo®, potentially contain SSC that could be a source of spermatozoa. The method used for cryopreserving TT may affect the integrity and number of SSC. Therefore, identifying alterations in the seminiferous tubules (ST) of frozen-ndash;thawed-NWR TT will provide insight into the condition of the SSC. Therefore, our aims were to (1) determine the effect of freezing rhinoceros TT on the structure of epithelium, and (2) identify SSC (GFRα1, GPR125) and pluripotent (SSEA-4 and Oct-4) markers. Testicular tissue of an adult NWR and a stillborn southern white rhinoceros (SWR) were frozen by equilibration of TT for 30 min at 4.0°C in PBS and 1.5 M dimethyl sulfoxide (DMSO), cooled at 2.0°C/min to −4.0°C, 0.3°C/min to −40°C, and plunged into liquid nitrogen. Tissues were thawed at 37°C in a water bath and DMSO removed in a 4-step dilution. Tissue was then fixed, dehydrated, and paraffin embedded. For morphological evaluations, frozen-ndash;thawed tissue was sectioned and stained with hematoxylin and eosin (H&E). The TT from both rhinoceros collected immediately after death (fresh) and stained with H&E were used as a control for cryopreservation. Localization of SSC and pluripotent markers in ST of frozen-ndash;thawed TT was detected by immunohistochemistry. Morphologically, fresh-NWR TT was severely altered, displaying large epithelium gaps and partial (62.2%) or total detachment (37.7%) from, and slight damage (35.5%) to, the basement membrane. The number of pyknotic nuclei per ST was moderate (15.6 ± 7.2%). Many of these changes could have resulted from autolysis and handling before tissue preparation. In contrast, histological appearance of fresh-SWR was good, with 98.3% of the tubules intact, and a small proportion of pyknotic cells (0.8 ± 1.5%). Seminferous tubule (n = 30/male) length and width (μm; ± SEM) differed between NWR (635.2 ± 34.4 × 214.6 ± 10.8) and SWR (277.7 ± 13.8 × 73.2 ± 2.4; P < 0.05). Damages after cryopreservation compared with fresh tissue comprised (1) epithelium detachment, NWR = 100% (P < 0.0001), and SWR = 43.3% (P < 0.001); (2) basement membrane alteration, only in NWR (93.0%; P < 0.001); and (3) decreased length and width in the ST, NWR = 409.4 ± 18.1 × 173.4 ± 8.2 (P < 0.05), and SWR = 195.2 ± 8.3 × 61.6 ± 2.8 (P < 0.05), with loss of lumen in both males. Immunohistochemistry revealed that NWR expressed GFRα1 and GPR125 at various stages of spermatogenqaesis, whereas Oct-4 was detected in few cells. In contrast to NWR, Oct-4 expression in SWR was located at the basement membrane; SSEA-4 was not detected in either male. In conclusion, freezing-induced morphological alterations in rhinoceros ST and positive expression of markers for SSC and pluripotency suggest the presence of SSC. Further studies are required to evaluate the viability of rhinoceros SSC.

Reproductive performance parameters in a large population of game-ranched white rhinoceroses (Ceratotherium simum simum)

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 2008 and 2016, reproductive performance was analysed in 1,354 animals kept in a 8000 hectares game-ranched environment. Descriptive statistics of this captive population showed an average annual herd growth (%) of 7 .0±0.1 (min -9 –max 15). Average calving rates were calculated as an annual calving rate of 20% and biennial calving rate of 37% adult females calving per year. Females had a median age of 83.2 months at first calving (IQR 72.9–110.7) and inter-calving intervals of 29.2 (IQR 24.6–34.8) months. Furthermore, translocations of animals did not interfere with reproductive success in terms of inter-calving periods or age at first calving. Multivariate models showed a clear seasonal calving pattern with a significant increase of the number of calvings during December–April when compared to April–December. Our results did not show any significant skewed progeny sex ratios. Weather observations showed no significant influence of rain or season on sex ratios of the calves.

Red light improves spermatozoa motility and does not induce oxidative DNA damage

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 importance to the practical application of this technique is the absence of DNA damage caused by radiation exposure. In this study, we examine the effect of 633 nm coherent, red laser light on sperm motility using a novel wavelet-based algorithm that allows for direct measurement of curvilinear velocity under red light illumination. This new algorithm gives results comparable to the standard computer-assisted sperm analysis (CASA) system. We then assess the safety of red light treatment of sperm by analyzing, (1) the levels of double-strand breaks in the DNA, and (2) oxidative damage in the sperm DNA. The results demonstrate that for the parameters used there are insignificant differences in oxidative DNA damage as a result of irradiation.

Rewinding the process of mammalian extinction

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, we convened a multidisciplinary meeting under the name "Conservation by Cellular Technologies." The outcome of this meeting and the proposed road map that, if successfully implemented, would ultimately lead to a self-sustaining population of an extremely endangered species are outlined here. The ideas discussed here, while centered on the northern white rhinoceros, are equally applicable, after proper adjustments, to other mammals on the brink of extinction. Through implementation of these ideas we hope to establish the foundation for reversal of some of the effects of what has been termed the sixth mass extinction event in the history of Earth, and the first anthropogenic one. Zoo Biol. 35:280-292, 2016. © 2016 The Authors. Zoo Biology published by Wiley Periodicals, Inc.

Chelonian perivitelline membrane-bound sperm detection: A new breeding management tool

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 in chelonian eggs lacking embryonic growth is equally challenging, PVM-bound sperm detection may also be a promising tool for the reproductive management of turtles and tortoises. This study is the first to successfully demonstrate the use of PVM-bound sperm detection in chelonian eggs. Recovered membranes were stained with Hoechst 33342 and examined for sperm presence using fluorescence microscopy. Sperm were positively identified for up to 206 days post-oviposition, following storage, diapause, and/or incubation, in 52 opportunistically collected eggs representing 12 species. However, advanced microbial infection frequently hindered the ability to detect membrane-bound sperm. Fertile Centrochelys sulcata, Manouria emys, and Stigmochelys pardalis eggs were used to evaluate the impact of incubation and storage on the ability to detect sperm. Storage at -20°C or in formalin were found to be the best methods for egg preservation prior to sperm detection. Additionally, sperm-derived mtDNA was isolated and PCR amplified from Astrochelys radiata, C. sulcata, and S. pardalis eggs. PVM-bound sperm detection has the potential to substantially improve studies of artificial incubation and sperm storage, and could be used to evaluate the success of artificial insemination in chelonian species. Mitochondrial DNA from PVM-bound sperm has applications for parentage analysis, the study of sperm competition, and potentially species identification.

Transfer and detection of freshly isolated or cultured chicken (Gallus gallus) and exotic species' embryonic gonadal germ stem cells in host embryos

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 critically endangered species. This project evaluated the possibility of using xenotransfer of embryonic gonadal germline stem cells (GGCs) for future reintroduction of their germplasm into the gene pool. We examined and compared the host gonad colonization of freshly isolated and 3 day (3d) cultured donor GGCs from chicken and 13 species of exotic embryos. Following 3d-culture of GGCs, there was a significant increase in the percentage of stem cell marker (SSEA-1, -3, -4) positive cells. However, the percentage of positive host gonads with chicken donor-derived cells decreased from 68% (fresh) to 22% (3d), while the percentage of exotic species donor-cells positive host gonads decreased from 61% (fresh) to 49% (3d-cultured). Donor GGCs from both chicken and exotic species were localized within the caudal endoderm, including the region encompassing the gonadal ridge by 16 hours post-injection. Furthermore, donor-derived cells isolated from stage 36 host embryos were antigenic for anti SSEA-1, VASA/DDX4 and EMA-1 antibodies, presumably indicating maintenance of stem cell identity. This study demonstrates that GGCs from multiple species can migrate to the gonadal region and maintain presumed stemness following xenotransfer into a chicken host embryo, suggesting that germline stem cell migration is highly conserved in birds.

109 DEVELOPMENT OF A SPERM CRYOPRESERVATION PROTOCOL FOR THE ARGENTINE BLACK AND WHITE TEGU (TUPINAMBIS MERIANAE)

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 black and white tegus were captured in the Florida Everglades. Following postmortem examination, sperm was collected by flushing the vas deferens and used as a model for the development of sperm cryopreservation protocols for related endangered lizards. Initial motility score (IMS; % motile × speed of progression2), plasma membrane integrity (IPL) and acrosome integrity (IAC) were recorded before freezing. Sperm was extended in TES and Tris (TEST)-yolk buffer with a final glycerol or dimethyl sulfoxide (DMSO) concentration of 8, 12, or 16%, and frozen in vials at 0.3, 1, or 6.3°C min–1. Vials were thawed at 37°C for 90 s. Cryoprotectant (CPA) was removed by centrifugation and resuspension of the sperm pellet in M199, at which time (T0) all variables were assessed and expressed as the percentage of initial (%IMS, %IPL, and %IAC). Statistical tests included multivariate ANOVA (MANOVA) and Student's t-test. Over all CPA concentrations and freeze methods, DMSO was significantly better than glycerol in maintaining %IMS (P = 0.01; 37.32 ± 3.5 and 25.44 ± 3.09, respectively) and %IAC (P < 0.01; 81.45 ± 3.45 and 22.99 ± 3.03, respectively). The 2 CPA were equally successful in protecting %IPL (P = 0.77; 56.61 ± 5.62 and 54.42 ± 4.93, respectively). The slowest freeze rate of 0.3°C min–1 was more successful than 1 and 6.3°C min–1 in preserving %IMS (P = 0.01; 37.85 ± 3.29, 26.03 ± 4.45, and 21.91 ± 4.45, respectively) and %IPL (P < 0.01; 77.43 ± 2.54, 27.99 ± 3.44, and 42.32 ± 3.44, respectively). The %IAC was not significantly affected by freeze rate (P = 0.14; 58.06 ± 6.89, 36.14 ± 9.33, and 42.99 ± 9.33, respectively). The interaction between CPA and freeze method affected %IMS (P < 0.01) and %IAC (P < 0.01), but did not affect %IPL (P = 0.28). All variables were affected (P < 0.05) by concentration of cryoprotectant as well as the interaction between freeze method and cryoprotectant concentration. To simplify these analyses and to determine the best overall freeze method for this species, a sperm quality index (SQI) was calculated, giving equal weight to each of the 3 measured indicators of cryosurvival. Table 1 depicts the product of %IMS, %IPL, and %IAC for each treatment. Because there were significant interactions between treatment parameters, each treatment was compared with all others (a–f). The SQI analysis revealed that tegu sperm frozen at 0.3°C min–1 in 8% DMSO exhibited a significantly higher post-thaw viability compared with all other treatments. Table 1.Sperm quality index (SQI) of thawed tegu sperm

Xenogeneic transfer of adult quail (Coturnix coturnix) spermatogonial stem cells to embryonic chicken (Gallus gallus) hosts: a model for avian conservation

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 (model for exotic species) spermatogonial stem cells were xenogeneically transferred to stages 14-17 chicken host embryos. Fluorescent cellular dyes, quail-specific antibodies, and quail-specific quantitative PCR confirmed donor cell migration to and colonization of the host gonadal ridge. Donor-derived cells were observed by fluorescent microscopy in the caudal area as early as 2 h after injection, in the gonadal ridge at 4 h after injection, as well as in the gonads of stages 35-38 host embryos. Four of eight donor-derived cell flow cytometry-positive host gonads were confirmed by quantitative PCR using quail-specific primers. There was no statistically significant effect of host stage of injection, host gonad isolation stage, or host sex on the number of hosts positive for donor cells or the percent of donor-derived cells per positive gonad. Donor-derived cells isolated from stages 35-38 host gonads costained with the germ stem cell marker SSEA-1, indicating that the donor-derived cells have maintained stem cell-ness. This is the first study to suggest that it is feasible to rescue adult germ stem cells of deceased birds to prolong the reproductive lifespan of critically endangered species or genetically valuable individuals by transferring them to an embryonic chicken host.

177 IN VITRO MATURATION AND FERTILIZATION OF OVARIAN OOCYTES OF FREE-RANGING GEMSBOK (ORYX GAZELLA)

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 addax (Addax nasomaculatus). Gemsbok were introduced to the White Sands Missile Range by the New Mexico Department of Game and Fish to preserve the habitat by providing big game hunting, which ensures the support and lobby of hunters. Gonads were collected from hunted gemsbok and transported in PBS to the laboratory, where gametes were harvested. Testes were stored at 4°C in PBS until sperm were needed for IVF (18 to 28 h). Ovaries were sliced to release follicular oocytes, which were placed in maturation medium (TCM-199 with FCS, pyruvate, gentamicin and LH, FSH and oestradiol) for 20- to 22-h in vitro maturation culture at 38.8°C in 5% CO2 in air. Oocytes were then washed [Tyrode lactate (TL)-HEPES with BSA, pyruvate and gentamicin] and placed in groups of 5 to 10 in 50-μL drops of IVF-TL medium supplemented with pyruvate, gentamicin and BSA. Sperm were allowed to swim out of sliced epididymides into room temperature IVF-TL medium and then equilibrated for 30 min at 38.8°C. Approximately 2 × 103 motile sperm were added to each oocyte drop and incubated under oil for 21 to 23 h at 38.8°C in 5% CO2 in air. Domestic cattle oocytes were matured in maturation medium at 39°C during shipment to the field site, where they were washed and transferred to IVF medium as described for gemsbok oocytes. Approximately 1.7 × 103 motile gemsbok sperm were added to each drop and oocytes were incubated as described for gemsbok oocytes. At the end of IVF culture, oocytes of both species were stripped of granulosa cells and placed in embryo medium (SOF supplemented with BSA, essential and nonessential amino acids, pyruvate and gentamicin; all media formulations from Applied Reproductive Technologies, Madison, WI, USA) at 38.8°C in 5% CO2 in air. Embryo culture medium was refreshed after 48 h. Embryos were removed from culture after 6 days, examined for cleavage and fixed in PBS:formalin for staining and further analysis. Although gemsbok sperm were capable of fertilizing domestic cow oocytes at the same rate (38.3%) as gemsbok oocytes (37.1%), the antelope oocytes cleaved at a higher rate (29% vs cattle at 15.3%). These results indicate that chilled epididymal gemsbok sperm is capable of fertilizing gemsbok and domestic cattle oocytes and that protocols designed for in vitro maturation and fertilization of cattle oocytes may be successfully used in the field to produce gemsbok embryos (Table 1). Table 1.Fertilization of in vitro-matured gemsbok and cattle oocytes by chilled epididymal gemsbok sperm The authors thank the New Mexico Department of Game and Fish, Troylyn Zimmerly, Dana Powers and the Biology Department of New Mexico Institute of Mining and Technology.

117 CRYOPRESERVATION OF SNAKE SEMEN: ARE WE FROZEN IN TIME?

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 protocols for semen evaluation, cooling, or freezing are described in the 4 known publications on snake semen cryopreservation. In this initial study, semen was collected noninvasively from 4 live adult red diamond rattlesnakes (Crotalus ruber) by ventral massage. An aliquot of each ejaculate was diluted in Ham's F10 and evaluated for motility and speed of progression (SOP, scale of 1–5, 5 being fastest) before and after freezing. Because ejaculate volumes were very small, each one was subjected to 2 to 4 treatments only. Samples were diluted in Lake's extender with 2 or 4% dimethyl sulfoxide or Test-Yolk extender with 4%, 8%, or 10% glycerol before cooling to 4°C. Semen extended with Lake's (a common avian semen extender) was then frozen by one of two protocols (FP): FP1, pelleted in liquid nitrogen vapor; FP2, placed in cryovials in an alcohol bath for 4 h in a –80°C freezer (cooling rate of 1°C min–1). Semen extended with Test-Yolk (a widely used mammalian semen extender) was frozen by one of two protocols: FP3, placed in cryovials in a controlled-rate freezer and cooled at 1°C min–1 to –20°C, then 50°C min–1 to –80°C; FP4, placed in cryovials in a controlled-rate freezer and cooled at 1°C min–1 to –8°C, then 3°C min–1 to –16°C, then 5°C min–1 to –80°C. Interestingly, semen frozen in Lake's extender exhibited no post-thaw motility, regardless of dimethyl sulfoxide concentration or FP (Table 1). In contrast, all semen frozen in Test-Yolk exhibited motility post-thaw. Semen from male 42 frozen by FP3 with 8% glycerol resulted in the greatest post-thaw motility of all treatments for both males. However, the same treatment for male 122 was not as successful, suggesting a possible male effect on semen cryosurvival (Table 1). The single sample frozen with 4% glycerol exhibited the lowest post-thaw motility, indicating that higher concentrations of the cryoprotectant may be beneficial to snake sperm. The exciting results of this preliminary study may guide future research in the long-neglected field of snake semen cryopreservation. Table 1.Motility/speed of progression for fresh and cryopreserved semen of red diamond rattlesnakes frozen with Test-Yolk extender and glycerol

An interdisciplinary systems approach to study sperm physiology and evolution

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-time automated tracking and trapping system (RATTS) is described that provides a remote user-friendly robotic interface. The combination of laser tweezers, fluorescent imaging, and RATTS can measure sperm swimming speed and swimming force simultaneously with mitochondrial membrane potential (MMP). The roles of two sources of adenosine triphosphate in sperm motility/energetics are studied: oxidative phosphorylation, which occurs in the mitochondria located in the sperm midpiece, and glycolysis, which occurs along the length of the sperm tail (flagellum). The effects of glucose, oxidative phosphorylation inhibitors, and glycolytic inhibitors on human sperm motility are studied. This combination of photonic physical and engineering tools has been used to examine the evolutionary effect of sperm competition in primates. The results demonstrate a correlation between mating type and sperm motility: sperm from polygamous (multi-partner) primate species swim faster and with greater force than sperm from polygynous (single partner) primate species. In summary, engineering and biological systems are combined to provide a powerful interdisciplinary approach to study the complex biological systems that drive the sperm toward the egg.

Methods of estrus detection and correlates of the reproductive cycle in the sun bear (Helarctos malayanus)

The objective was to explore multiple methods for detecting and characterizing the reproductive cycle of the sun bear (Helarctos malayanus). Thirteen H. m. euryspilus females, loaned from the Malaysian government to US zoos, were used. Fecal metabolite concentrations of estrogen and progesterone were compared to vaginal cytology, changes in genital appearance, and behavior (videotapes and zookeeper observations). Cytology and video behavior were characterized during five hormonally defined states: high, low, and baseline progesterone, estrus, and high estrogen. Among states, there were significant differences in cytology and behavior. Sexual, affiliative, and stereotypic behaviors were highest during estrus, whereas affiliative and social behaviors were lowest during high progesterone. In this captive breeding population, 30.8% of females cycled two or three times a year, 30.8% cycled once a year, and 38.5% did not cycle during this study. Inter-estrus intervals were (mean ± SEM) 115.7 ± 6.3 d (range, 101-131). Spearman rank correlations were significant between both ordinal sexual and affiliative behaviors and vulva swelling and color. Sexual behavior was significantly positively correlated with superficial and keratinized cells, but negatively correlated with parabasal and basophilic cells in cycling females (opposite pattern for appetitive behavior). In conclusion, data for cytology, vulva changes and behavior were consistent with, and complementary to, hormonal data; collectively, they delineated estrus and identified specific reproductive types.

Comparison of glycolysis and oxidative phosphorylation as energy sources for mammalian sperm motility, using the combination of fluorescence imaging, laser tweezers, and real-time automated tracking and trapping

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 mitochondria located in the sperm midpiece and glycolysis, which occurs along the length of the sperm tail (flagellum). The relationships between (a) swimming speed and MMP and (b) swimming force and MMP are studied in dog and human sperm. The effects of glucose, oxidative phosphorylation inhibitors and glycolytic inhibitors on human sperm motility are examined. The results indicate that oxidative phosphorylation does contribute some ATP for human sperm motility, but not enough to sustain high motility. The glycolytic pathway is shown to be a primary source of energy for human sperm motility.

PERMANENT GENETIC RESOURCES: Isolation and characterization of microsatellite loci in the North Island brown kiwi, Apteryx mantelli

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). Microsatellite polymorphism was subsequently determined using 65 individuals. There were two to seven alleles for each polymorphic locus with heterozygozity ranging between 0.04 and 0.86. These primers will be used in future studies to determine the level of extra-pair copulation, dispersal patterns, and genetic diversity within and between wild populations of NIBK.

Use of laser tweezers to analyze sperm motility and mitochondrial membrane potential

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, DiOC2(3), that reports the MP across the inner membrane of the mitochondria located in the sperm's midpiece. Individual sperm are tracked to calculate VCL. Pesc is measured by reducing the laser power after the sperm is trapped using laser tweezers until the sperm is capable of escaping the trap. The MP is measured every second over a 5-s interval during the tracking phase (sperm is swimming freely) and continuously during the trapping phase. The effect of the fluorescent probe on sperm motility is addressed. The sensitivity of the probe is measured by assessing the effects of a mitochondrial uncoupling agent (CCCP) on MP of free swimming sperm. The effects of prolonged exposed to the laser tweezers on VCL and MP are analyzed. The system's capabilities are demonstrated by measuring VCL, Pesc, and MP simultaneously for individual sperm. This combination of imaging tools is useful to quantitatively assess sperm quality and viability.

Analysis of sperm motility using optical tweezers

This study examines the use of optical trapping as a quantitative measure of sperm motility. The effects of laser trap duration and laser trapping power on sperm motility are described between sperm swimming force, swimmimg speed, and speed of progression (SOP) score. Sperm (SOP scores of 2-4) were trapped by a continuous-wave 1064 nm single-point gradient laser trap. Trap duration effects were quantified for 15, 10, and 5 seconds at 420 mW laser power. Laser power effects were quantified at powers of 420 mW, 350 mW, 300 mW, and 250 mW for five seconds. Swimming force, swimming speed, and SOP score relationships were examined at a trap duration and trapping power shown to minimally affect sperm motility. Swimming forces were measured by trapping sperm and subsequently decreasing laser power until the sperm escaped the trap. Swimming trajectories were calculated by custom-built software, and SOP scores were assigned by three qualified sperm scoring experts. A ubiquitous class of sperm were identified that swim with relatively high forces that are uncorrelated to swimming speed. It is concluded that sperm swimming forces measured by optical trapping provide new and valuable quantitative information to assess sperm motility.

Papanicolaou staining of exfoliated vaginal epithelial cells facilitates the prediction of ovulation in the giant panda

The giant panda is seasonally monoestrus, experiencing a single estrous with spontaneous ovulation in the spring. Therefore, accurate monitoring of the estrous cycle to pinpoint the time of ovulation is critical for the success of timed mating or artificial insemination. Analysis of exfoliated vaginal epithelial cells is a simple technique that rapidly yields information about the estrous status of a panda. Vaginal swabs were obtained during five estrous cycles of two nulliparous females. Cells were stained with the trichrome Papanicolaou and classified as basophils, intermediates or superficials. The color of stained cells, basophilic, acidophilic or keratinized, was recorded as a characteristic independent of the three standard cell types. The day urinary conjugates of estrogen fell from peak levels was considered the day of ovulation. A chromic shift occurred 8-9 days before ovulation when the majority of exfoliated vaginal cells changed from basophilic (blue) to acidophilic (pink) without accompanying nuclear or cytoplasmic changes. A second chromic shift was consistently observed 2 days prior to ovulation when keratinized (orange) cells replaced acidophils as the majority of vaginal cells. Monochrome staining of vaginal cells is sufficient to quantify superficial cells, which is a useful adjunct to behavioral and endocrinological data in determining estrous in the giant panda. However, the timing and duration of superficial cell elevations are substantially different between and within individual females, which limits the accuracy of timing ovulation for artificial insemination. The predictive value of vaginal cytology was greatly enhanced with the trichrome stain and evaluation of cell color.