Cloning through somatic cell nuclear transfer (SCNT) remains highly inefficient twenty years after the first demonstration of the technology with the birth of Dolly. By increasing efficiency by selecting the embryos early in development that are most likely to succeed following transfer into a surrogate mother, the technology could be more routinely utilized to enhance animal agriculture production. SCNT is believed to be highly inefficient as a result of incorrect DNA methylation and gene expression that are accumulated because of the SCNT technique. We proposed the use of a non-toxic, non-invasive detector of cell death, to quantitatively assess embryo competency prior to embryo transfer. We believed we could use SR-FLICA to identify the embryos with low levels of cell death as a result of proper DNA methylation and gene expression. By analyzing the whole embryo, differences in gene expression and DNA methylation were identified in embryos with high and low levels of cell death. However, the level of cell death did not prove to be a reliable indicator of embryo quality in predicting pregnancy outcome. This data supports the commonly held hypothesis that DNA methylation and gene expression after SCNT have random defects as a result of the random nature of resetting the DNA for embryo development. More research is required to identify the embryos which will prove to be successful following SCNT and embryo transfer.

Separated from mainland Australia by the Bass Strait, Tasmania has acted as an island preserve maintaining large populations of many mammalian species presently uncommon, rare, or extinct on mainland Australia. There are few studies of Tasmanian mammal distributions. Recent distributional maps, based on information from surveys and mammal specimens, allowed for an investigation of the species density distributions of the terrestrial mammals of Tasmania. Compilation of species' distributional information into species density distributions provides an overview as to which areas may provide the most significant habitat for the greatest number of species; what geographic variations may influence species distributions; and which regions remain least surveyed for mammalian species in Tasmania.

Cluster analysis of a large body of data on 180 Oregon specimens of Eutamias minimus and E. amoenus suggest that overall length of skull, basal length of skull and length of palate are taxonomically critical. If their sum is less than 71.3 millimeters the animal is E. minimus. If the sum is greater than 72.7 millimeters the animal is E. amoenus. If the sum is between 71.3 and72.7 millimeters, other factors must be considered before the animal can be identified. Of the 180 specimens, there were 60 E. minimus, 114 E. amoenus, 2 hybrids, 2 unidentifiable and 2 mismatched skulls and skins.

Although cooperative behavior is generally acknowledged to occur among wolves, there is a lack of systematically collected data confirming the extent of development. The objectives of this study were to collect long-term, detailed observations documenting the role of social structure, seasonal influences, and individual participation in wolf pack cooperative activities. Individual cooperative strategies were associated with age, sex, and social positions and critically compared with results of similar studies. Emphasis was placed on quantifying group and dyadic relationships, focusing on reproductive strategies and dominance structure. Additional data were collected on denning behavior, maternal care behavior, scent marking, and spontaneous individual and group howling.

This thesis examined the effectiveness of DNA fingerprinting analysis for paternity ascertainment and the establishment of relatedness of captive Asian elephants (Elephas maximas). Eighteen Asian elephants from three North .American zoos were examined. Thirteen of these elephants were wild caught. Relationships between these elephants and the remaining elephants born in captivity were known.

Almost no work has been done on the brooding habits of Cucumaria curata Cowles 1902 from the Pacific Coast of North America. Most of the embryological investigations of holothurians on this coast have been with species having free swimming larval forms (Johnson and Johnson, 1950). Since the majority Holothurians have planktonic larvae, a study of the direct development found in C. curate might prove beneficial in comparing the ecological distribution of this species with those having planktonic larvae. The brooding type of development is found in polar species, but seldom found in warmer waters. This may have some direct effect on limiting the distribution of the species. After studying this particular type of development in C. curata, a need arose to investigate its physiology and ecology to ascertain the significance of its larval type to the distribution of the species in the community.

This investigation is based upon the occurrence of oral protozoans among 25 periodontalclasial patients in Stockton, California. It is concerned, in part, with the correlation of infections with age, sex and oral health of the host and, in part, with culture techniques. The specific cultivation of Trichomonas tenax was explored in an effort to employ an improved experimental medium. Trichomonas tenax and Endamoeba gingivalis are the only protozoans known to occur commonly in the human mouth. Distribution is cosmopolitan and there are no known endemic areas. Incidence of these two protozoans, among periodontalclasial patients, has not been reported since the study made by Jirovec, Bertos, Mezl, and Novack (1942).

The family Bucephalidae is unique in the class Trematoda by virtue of the mouth being situated near the mid-ventral portion of the body. Other characteristics of the family include: haptor near the anterior extremity; a simple, sac-like gut with pharynx and esophagus; genital pore ventral, just anterior to the posterior extremity; gonads posterior and vitellaria species live in the gut of marine and fresh-water fishes. The metacercariae are found encysted beneath the skin or in the nervous system of other fishes serving as second intermediate hosts. Sporocysts and cercariae have been recovered from a variety of lamellibranchs. A generalized life cycle of the bucephalids can be stated as follows: eggs discharged from the intestine of the definitive host produce free swimming miracidia which enter the mantle cavity of a lamellibranch; branching sporocysts develop within the gonads and, allegedly, other organs (although the writer observed them only in the gonads); cercariae are produced directly in the sporocysts or daughter sporocysts, and when mature are discharged through the excurrent siphon of the host. Woodhead (1931) described rediae in the sporocysts of Bucephalus elegans and Rhipidocotyle papillosum although Knickern (1950) and Ciorda (1956), working with Rhipidocotyle septpapillata and Rhipidocotyle papillosum respectively, failed to note a redial stage. The writer, too, has seen no rediae. The cercariae, when coming in contact with an appropriate fish, attach to it by means of long, filamentous tall appendages and finally bore into a suitable site for encystment, losing their tails on the way (Woodhead, 1927). The metacercariae reach the definitive host when the smaller fish is devoured. It is not uncommon for the same species of fish to act as both second intermediate and definitive hosts.

During the spring of 1955, while attending classes at the Pacific Marine Station, under the direction of Dr. Alden E. Nobel, Chairman of the Department of Zoology, College of the Pacific, Urechis caupo was introduced as a representative of the fauna of the mud flats of Tomales Bay. The unusual manner in which this animal lives would stimulate the curiosity of any student interested in biology, and especially those associated with marine life. The fact that the animal burrows its own home in a U-shaped tunnel and dwells there with three permanent commensals (Hesperonoë adventor, Skogsberg, a plynoid annelid; and 2 pinnotherid crabs, Scleroplax granulate, Rathburn, and Pinnixa franciscapa, Rathburn) is a unique characteristic. The goby fish, Clevelandia ios (Jordan and GIlbert), may also be considered a commensal, but it uses the burrow as a retreat rather than a permanent residence (Fisher, 1946). Studies on the early embryology of Urechis stimulated the writer to further study of the reproductive cycle. The puzzling descriptions and information pertaining to the immature gametes that are found in the coelomic fluid, coupled with the fact that no permanent gonad has been observed or indeed, that it may be wholly lacking, supplied a challenge that he could not ignore. The primary purpose of this investigation is to attempt to evaluate the reproductive cycle and to attempt to locate some type of germinal epithelium.

No description available.