Artificial spawning and rearing of lake sturgeon,Acipenser fulvescens,in Wild Rose State Fish Hatchery,Wisconsin, 1982–1983

Synopsis Attempts to culture lake sturgeon, Acipenser fulvescens, in the past have generally met with limited success. The Wisconsin Department of Natural Resources has been experimenting with artificial propagation of this species since 1979. The intent has been to develop egg collection and handling techniques, hatching regimes, larva and juvenile diet formulations, and to evaluate juvenile survival after stocking. Eggs were collected by caesarian section and fertilized with milt from ripe males taken during annual sturgeon spawning runs on the Fox and Wolf rivers in central Wisconsin. After insemination, the eggs were treated in a saturated solution of Bentonite clay and transported to the hatchery. Eggs were incubated at temperatures ranging from 13–16° C and embryos began hatching within 4 to 8 days. Hatching success ranged from 42 to 96%. Yolksac absorption was complete within 10 days of hatching. Larvae then became positively phototactic and swam actively as if searching for food. Successful larval diets consisted of live brine shrimp nauplii followed by larger zooplankton, primarily Daphnia sp. Juveniles grew best on diets of live Tubifex sp. and chopped earthworms. Liver, fish mash (ground up trout) and pelleted dry food were poorly accepted. Hatchery reared sturgeon grew more slowly than did wild fish.     

The effect of insemination time and sperm dose on pregnancy rate using sex-sorted ram sperm

The objective was to determine the optimum timing of insemination and minimum effective dose rate of sex-sorted ram sperm. Semen from three Merino rams was sorted into high purity X- and Y-chromosome bearing sperm populations. Ovulation was controlled in 732 Merino ewes using PMSG at progestagen pessary removal and GnRH 36 h later. Sorted (S) and non-sorted (NS) doses of 1 or 15 × 10⁶ motile, frozen-thawed sperm were inseminated laparoscopically at 50, 54, 58, 62, and 66 h after progestagen withdrawal. An additional treatment dose of 0.5 × 10⁶ S or NS sperm was inseminated at the 58 h time point (n = 60). Pregnancy was diagnosed by ultrasound at 60-62 d gestation. Both 1 × 10⁶ and 15 × 10⁶ sperm achieved similar pregnancy rates, regardless of sperm type, at 58 h (S1: 46 ± 9.4%; S15: 43 ± 9.3%; NS1: 41 ± 9.2%; NS15: 49 ± 9.4%). However, pregnancy rates were lower (P < 0.05) for doses of 1 than 15 × 10⁶ sperm inseminated at 50 (15 ± 6.3% vs. 36 ± 9.1%), 54 (14 ± 4.4% vs. 55 ± 7.3%), 62 (33 ± 6.9% vs. 54 ± 7.3%), and 66 h (29 ± 8.6% vs. 56 ± 9.5%). There was no difference between S and NS sperm for inseminations with 0.5 × 10⁶ motile sperm at 58 h after PR (15 ± 3.6% vs. 14 ± 3.3%), nor with 15 × 10⁶ motile sperm at all insemination times (49 ± 6.3% vs. 49 ± 6.3%). However, fertility was higher for S than NS sperm at the 1 × 10⁶ dose level (37 ± 6.1% and 16 ± 4.0%). More than 90% of lambs born were of the predicted sex. We hypothesise that the sorting process selects a homogeneous, fertile sub-population of sperm, removing those that are dead, damaged and morphologically abnormal.     

Insemination success discrepancy between long-term and short-term copulations in the provisioning shield bug, Parastrachia japonensis (Hemiptera: Cydnidae)

The duration of copulation in the gregarious shield bug, Parastrachia japonensis Scott (Hemiptera: Cydnidae), is of two types, the far more prevalent short-term copulation (average, 15 s) and the long-term coupulation (average, 23 min). Both types were thought to be equally effective in inseminating females. Recent evidence has suggested that there is, in fact, a discrepancy in insemination success between the two duration types of copulations. We carried out manipulated field studies to clarify the difference in insemination success between the two duration types and to determine whether there is some physical or physiological variability in females or males that might affect female receptivity to a long-term copulation. The findings indicated that, although a small percentage of short-term copulations resulted in some sperm transfer, long-term copulations were a far more effective way for males to inseminate females. Further, females experiencing long-term copulations were found to be at a slightly more advanced stage of ovarian development than those experiencing only short-term copulations, and may be deciding whether a long-term copulation occurs. Male size does not appear to affect copulation duration. It is concluded that the long-term type of copulation is the actual effective copulation duration in this species and the objective of all females. Possible factors that might contribute to the prevalence of these two copulation durations are discussed. Received: June 21, 1999 / Accepted: September 6, 1999     

Artificial insemination at 56 h after intravaginal progesterone device removal improved AI pregnancy rate in beef heifers synchronized with five-day CO-Synch + controlled internal drug release (CIDR) protocol

The objective was to determine whether timed artificial insemination (TAI) 56 h after removal of a Controlled Internal Drug Release (CIDR, 1.38 g of progesterone) insert would improve AI pregnancy rate in beef heifers compared to TAI 72 h after CIDR insert removal in a 5-days CO-Synch + CIDR protocol. Angus cross beef heifers (n = 1098) at nine locations [WA (5 locations; n = 634), ID (2 locations; n = 211), VA (one location; n = 193) and WY (one location; n = 60)] were included in this study. All heifers were given a body condition score (BCS; 1-emaciated; 9-obese), and received a CIDR insert and 100 μg of gonadorelin hydrochloride (GnRH) on Day 0. The CIDR insert was removed and two doses of 25 mg of dinoprost (PGF_2α) were given, first dose at CIDR insert removal and second dose 6 h later, on Day 5. A subset of heifers (n = 629) received an estrus detector aid at CIDR removal. After CIDR removal, heifers were observed thrice daily for estrus and estrus detector aid status until they were inseminated. Within farm, heifers were randomly allocated to two groups and were inseminated either at 56 h (n = 554) or at 72 h (n = 544) after CIDR removal. All heifers were given 100 μg of GnRH at AI. Insemination 56 h after CIDR insert removal improved AI pregnancy rate compared to insemination 72 h (66.2 vs. 55.9%; P < 0.001; 1 - β = 0.94). Locations, BCS categories (≤ 6 vs. > 6) and location by treatment and BCS by treatment interactions did not influence AI pregnancy rate (P > 0.1). The AI pregnancy rates for heifers with BCS ≤ 6 and > 6 were 61.8 and 60.1%, respectively (P > 0.1). The AI pregnancy rates among locations varied from 54.9 to 69.2% (P > 0.1). The AI pregnancy rate for heifers observed in estrus at or before AI was not different compared to heifers not observed in estrus [(65.4% (302/462) vs. 52.7% (88/167); P > 0.05)]. In conclusion, heifers inseminated 56 h after CIDR insert removal in a 5-days CO-Synch + CIDR protocol had, on average, 10.3% higher AI pregnancy rate compared to heifers inseminated 72 h after CIDR insert removal.     

Sperm cell architecture, insemination, and fertilization in the model fern, Ceratopteris richardii

Motile sperm cells of land plants are released directly into the environment and encounter numerous constraints on their way to the egg. Sperm cell organization, shape, size, and plasticity are crucial to the processes associated with fertilization. We conducted an ultrastructural investigation to detail insemination (sperm release, swimming and movement within the archegonium) and fertilization in the model fern Ceratopteris richardii. Gametophytes were grown from spores using sterile culture techniques and flooded in water when sexually mature. Materials were examined at different stages post-flooding. During insemination in C. richardii, the sperm cytoskeleton and flagella rearrange, and the coils of the cell extend while entering the neck canal. In this nearly linear configuration, the dense ridge, a densely compacted band of filaments presumed to be actin, expands to surround the leading edge of the sperm cell. This ridge fuses with the receptive site on the female gamete and is the sperm component that initiates contact with the egg nuclear envelope. All cellular components, except plastids, enter the egg cytoplasm. Sperm mitochondria are distinguishable from those of the egg because they are encased by two or three additional membranes and are sequestered from the zygote cytoplasm. During karyogamy, the sperm components, including the microtubule cytoskeleton (spline) and flagella, maintain their spatial integrity. Microtubules play key roles not only in sperm cell structure but also in facilitating karyogamy in this fern. After karyogamy is completed, microtubule arrays of the sperm cell and the components of the locomotory apparatus are disassembled. We provide the first demonstration of the likely involvement of sperm actin in egg penetration in land plants and new insights into the fate of paternal organelles. This study points to the roles sperm cell structure and dynamics play in the intricate processes of insemination and fertilization in land plants.     

Sperm mortality, insemination and fertilization in the damselfly Ischnura senegalensis: comparisons between wild and inbred populations

Inbreeding can have deleterious effects on individual or population fitness. To avoid fitness reduction, individuals may adopt behavioral or physiological mechanisms to reduce their investment in the production of offspring with genetically similar mates. We examined whether insemination by inbred males introduced more dead sperm than insemination by wild males by counting sperm in female Ischnura senegalensis (Rambur) sperm storage organs. If inbred males inseminated fewer or lower-quality sperm, females would avoid inferior sperm. Our results revealed three features of damselfly inbreeding: insemination failed in a larger proportion of inbred pairs than in wild pairs, inbred pairs showed significantly reduced fertility, and the numbers of live and dead sperm in an inbred female’s sperm storage organs did not differ from those in wild females. These results suggested that neither sperm quantity nor sperm quality was responsible for low fertility to a significant extent, but some kind of female quality, such as sperm usage or storing ability, was. Although inbred pairs had lower fertility, there were no significant differences between inbred and wild pairs in the total numbers of live or dead sperm. It thus seemed that female choice at the insemination stage was responsible for low fertility rather than sperm quantity or quality measured by live-to-dead ratio.     

Fertility trial in Zebu cattle after a natural or controlled estrus with prostaglandin F2 Alpha, comparing natural mating with artificial insemination

With the object of comparing reproductive efficiency obtained by natural mating and by artificial insemination (AI), not only following a natural estrus but also after an induced estrus with PGF2Alpha in Zebu cattle in the tropics, 244 adult cows were divided into 4 groups. Group I (N = 69) and Group III (n = 62) were injected with 25 mg of PGF2Alpha when a functional CL was found on rectal examination. Group I was inseminated and group III was served by natural mating, both groups within five days after injection. Groups II (n = 57) and IV (n = 56) were left untreated, group II being AI and group IV ran with a fertile bull for 22 days. Estrus detection was carried out only in the injected groups (I and III) for 15 minutes every three hours between 0600 and 1800. All information was analyzed by linear trigonometric models. The onset of estrus occurred on average 68.7 h after injection in group I and 59.5 h in group III. However only 46.3% and 54.8% of animals were detected in estrus in group I and III respectively, the difference being significant (P < 0.10). Conception rates were 18.6%, 29.8%, 19.3% and 33.9% for groups I, II, III, and IV respectively. A significant difference (P < 0.10) existed between the injected groups and the untreated ones.     

On the mechanism of sperm release in three gobiid fishes (Teleostei: Gobiidae)

Synopsis In fish, gamete release is commonly assumed to be synchronous in externally inseminating fishes. By collecting and counting the number of sperm and eggs released during separate matings in three demersal spawners, the mediterranean gobies, Zosterisessor ophiocephalus, Gobius niger, and Knipowitschia panizzae, we observed that gametes are released asynchronously. Males release sperm before females start laying their eggs. Sperm is released in the form of sperm trails laid on the nest surface; subsequently active spermatozoa leave the trails and move in the water for several minutes. Sperm trails consist of bands of viscous material in which sperm is embedded. In most cases eggs are not laid directly over the sperm trail, suggesting that sperm may contact the eggs after the latter are released in the water. Male sperm duct glands, seminal vesicles, known to secrete mucosubstances, are likely involved in the production of sperm trails. The possible influence of this mode of insemination on the mating style of marine gobies is discussed.     

The storage of spermatozoa in the oviducal glands of western North Atlantic sharks

Synopsis Spermatozoa stored in oviducal glands of sharks sampled off the North American east coast were revealed by viewing stained tissue sections using light microscopy. Of eleven species surveyed, sperm were found in nine:Alopias vulpinus, Lamna nasus, Carcharhinus obscurus, Carcharhinus plumbeus, Galeocerdo cuvieri, Prionace glauca, Rhizoprionodon terraenovae, Sphyrna lewini andSphyrna tiburo. Three insemination patterns are proposed to account for differences noted in these findings: (1) non-storage/immediate insemination for sharks such asLamna nasus; (2) short-term storage/delayed insemination as found in sharks in which ovulation is prolonged over weeks or months such asRhizoprionodon terraenovae, and (3) long-term storage/repeated insemination, a characteristic of nomadic sharks such asPrionace glauca andCarcharhinus obscurus which can store sperm in specialized tubules for months to years.     

Mating behavior of the predatory mite <Emphasis Type="Italic">Kampimodromus aberrans</Emphasis> (Acari: Phytoseiidae)

The mating behavior of the predatory mite Kampimodromus aberrans was studied in the laboratory at a constant temperature of 25± 1 °C and a photoperiod of 16:8 (L:D). Forty pairs of newly emerged virgin females and unmated males, were maintained separately on leaf discs and their mating behavior, was observed continuously under a stereomicroscope. The mean time until first contact of female and male individuals was approximately 8.2 min. After the first contact the male moved to the top of the female’s dorsum and subsequently underneath her in approximately 1.7 min and then the paired mites walked around on the leaf surface for approximately 7.5 min. Afterwards, the mites remained still in the mating position, i.e. the male beneath the female for an average period of 230.5 min. After mating, most of the females had one spermatophore in one of their spermathecae, whereas a few had one spermatophore in both spermathecae.