Differences In Hatching Research Articles

Improved methods for harvesting and counting synchronous populations of Artemia nauplii for use in developmental toxicology

Artemia nauplli have, within recent years, gained popularity as a test organism for short-term toxicity testing. Because nauplii exhibit rapid development and growth within 48 hr after hatch, their potential as a model organism for teratology screening has been considered. To do this, synchronous populations of nauplii at different developmental intervals must be available. A dual-chamber hatching vessel which enables multiple harvesting of synchronous populations of nauplii from one sample of prepared cysts has been developed. An accumulation period of 2 hr defines the synchronous population and produces around 1000 nauplii among five hatching vessels. The body lengths of nauplii harvested 2 to 9 hr after the initial harvest were equivalent to and lower than that of animals incubated at the hatching temperature (31 ± 1°C); e.g., the body length of freshly harvested nauplii at 9 hr was 473 ± 6.2 μm (±SE) and for nauplii incubated for 8 to 10 hr, the body lengths were 643 ± 10.7 and 702 ± 10.9 μm, respectively. A counting method was developed that enabled precise counting up to 400 nauplii in suspension and distinguishing dead from live nauplii. Measurements of body length, body water volume, and whole animal DNA and protein of nauplii harvested sequentially from the same of sample prepared cysts indicated that in addition to temporal differences in hatching, the nauplii may differ both physically and chemically.

Reproduction of the Turquoise-Browed Motmot at Archaeological Ruins in Yucatan

The reproductive biology of the Turquoise-browed Motmot (Eumomota superciliosa) was studied at five sites in YucatAn, Mexico, during 1980, 1981, and 1982. Pairs of E. superciliosa reared their young within beam-socket recesses in the walls of archaeological ruins. This novel situation facilitated the gathering of data, previously unpublished for E. superciliosa, on laying interval, hatch percentage, and nestling survival. Comparisons of this man-impacted population with other, relatively undisturbed populations of the species were possible. Initiation of laying was correlated with the onset of local spring (May-June) rainfall. Eggs were deposited at approximately 48-hour intervals. Mean fresh egg weight was 8.07 g during 1982. A clutch of four represented approximately 50% of adult body weight. In 1980, clutch size averaged 3.86 eggs per nest; hatch, 2.41 eggs per nest; nestling survival to 24 days, 1.05 young per nest; in 1982, these means were 3.97, 2.56, and 1.56, respectively. Significant differences in hatch and nestling survival occurred between several sites; these are discussed in relation to site-specific predator proximity and rainfall patterns. THE TURQUOISE-BROWED MOTMOT (Eumomota superciliosa) is a conspicuous element in the avifauna of much of Middle America, present in both natural and disturbed habitats as well as xeric and mesic situations (Skutch 1947; Paynter 1955; Klaas 1968; Orejuela 1975, 1977, 1980). Its breeding behavior appears to be influenced strongly by local conditions-pairs may in relative isolation, in semi-colonial, or colonial fashion; sites utilized range from rock crevices to burrows in dirt and sand banks. Although such flexibility would seem to make E. superciliosa an excellent subject for investigations of comparative reproductive behavior and ecology, only two studies of its life history have been attempted (Skutch 1947; Orejuela 1977, 1980), and data on such important elements of its biology as laying interval, hatch percentage, and nestling survival have not been published. The fossorial nesting behavior of this motmot appears largely responsible for this omission. Where soils are deep, nest (eggs are laid on bare substrate) burrows are too long to be excavated by researchers without undue disturbance; under shallow soil conditions, motmots frequently use inaccessible crevices in vertical limestone exposures to rear their young (Skutch 1947, Orejuela 1975). At a number of localities in Yucatan, Mexico, however, E. superciliosa rears its young within beam-socket and ventilation recesses of archaeological ruins (Martin and Martin 1980). Within many of these, eggs and nestlings may be observed conveniently. Additionally, adults at these sites are conditioned to the presence of human visitors. Although the artificiality of such sites may seem at first to argue against their choice as areas for study, we view the situation pragmatically, and following Lack (1965), consider much of the northern hemisphere an artifact of man. We also believe that studies conducted in tropical areas modified by man are of particular present and future value. Here, as part of a program of comparative studies of avian populations in natural and impacted environments, (Martin 1980, 1981; Martin and Martin 1978), we (1) provide data on reproductive timing, clutch size, egg weight, hatch, and nestling survival in ruins-nesting Yucatan E. superciliosa, (2) discuss intersite differences in these data in terms of the general hypotheses directly relating environmental moisture and potential predator barriers to reproductive success, and (3) when possible, compare these data with those of Skutch (1947), Klaas (1968), and Orejuela (1975, 1977), taken on this species under more natural conditions in Guatemala, Honduras, and Mexico (Campeche). STUDY AREA AND METHODS Our five study sites lie within an area of primarily low second-growth, deciduous forest approximately 85 km S Merida, Yucatan, Mexico. Uxmal is located at approximately 20?20'N, 39?45'W; Kabah lies approximately 17 km SE Uxmal; Sayil, 6 km SE Kabah; Xlapak, 4 km E Sayil; Labna, 5 km E Xlapak. Tourist visitation ranges from relatively heavy at Uxmal to moderate at Sayil and Xlapak. Soils of this region are shallow and are underlain by limestone. Percolation to the water table is extremely rapid and surface water is essentially non-existent. Numerous sinkholes, cenotes, and cave entries pierce the limestone bedrock and frequently expose the underlying aquifer. Crevices in the walls of these declivities appear to be the natural breeding sites of E. superciliosa of this

Beltsville Poultry Semen Extender: 7. Comparison of Commercial Diluents for Holding Turkey Semen Six Hours at 15 C

The ability of three commercial semen diluents (Minnesota, I.M.V.-French and Universal) and the Beltsville Poultry Semen Extender (BPSE) to maintain the fertilizing capacity of turkey semen held 6 hr at 15 C was examined. Hens were inseminated weekly for 20 wk and hatchability of eggs was determined. Neither candling nor true fertility of semen diluted 1:1 in BPSE, the Minnesota, or I.M.V.-French diluent and held for 6 hr differed significantly from each other. Fertility of semen held 6 hr in BPSE or Universal diluent was lower than their respective unstored controls. No difference in fertility was observed between semen held in Minnesota or I.M.V.-French diluent and their unstored controls. Significantly higher hatch of fertile eggs and of all eggs set was obtained from hens inseminated with semen diluted (0 hr) with BPSE (90 and 86%) than all other diluents. Hatch of fertile eggs was higher from hens inseminated with semen held 6 hr in Universal (90%) and French (86%) extenders and lower for the Minnesota (78%) extender. No difference was observed in hatch of fertile eggs between the BPSE (84%) and French (86%) extender. Hatchability of all eggs set was higher when hens were inseminated with semen held 6 hr in the I.M:V.-French diluent (81%) when compared to hens inseminated with the Minnesota (75%) or Universal diluent (75%). No differences in hatch of all eggs set were noted when BPSE (77%) and the commercial extenders were compared.

Hatching rhythms in three species of Diclidophora (Monogenea) with observations on host behaviour.

Eggs of three species of Diclidophora were incubated in alternating 12 h periods of light and darkness at 13 degrees C. Eggs of D. merlangi collected at Arbroath hatched during the illumination period with most larvae being recovered in the first 4-6 h; some evidence of a seasonal difference in hatching of these eggs was found. Eggs of D. merlangi collected at Plymouth hatched with a peak of larval recovery in the 2 h period before the light came on. Eggs of D. luscae hatched over 'dusk' while those of D. denticulata hatched after the light was switched off. Neither mechanical disturbance nor the proximity of host tissue caused hatching in D. merlangi or D. luscae. Observations on the behaviour of the host fishes suggest that the hatching rhythms are adapted to specific host behaviour patterns.

Differences in hatch and development rates of potato cyst nematode pathotypes

Differences in hatch and development rates of potato cyst nematode pathotypes