bluuebunny/crossref_metadata_2025 huggingface dataset:
Protection of rabbit embryos against fracture damage from freezing and thawing by encapsulation in calcium alginate gel
Authors: Kojima T. , Hashimoto K. , Ito S. , Hori Y. , Tomizuka T. , Oguri N.
Published: June 2005

Avoidance of fracture damage to the zona pellucida during freezing and thawing is essential for the successful freezing of rabbit embryos. The aim of this study was to examine the effects of encapsulation of rabbit embryos in calcium alginate gel, prior to freezing, on damage to the non‐cellular components (zona and mucin coat) caused by freezing and thawing, and on the survival of embryos after thawing in vivo as well as in vitro. Morulae immersed in 2% sodium alginate in Ringer solution were aspirated into a Pasteur pipette. The contents of the pipette were then ejected into a 110 mM solution of calcium chloride. After 30 min, 1‐ to 2‐mm long semi‐solid cylinders, each including one embryo, were cut off with a surgical blade. In the presence of 11% dimethyl sulfoxide, the encapsulated embryos were cooled by the standard method and stored in liquid nitrogen. After rapid thawing, the alginate gel was mechanically removed from around the embryos, and the embryos were morphologically evaluated and allocated to different groups for examination of their development in vitro or in vivo. The percentage of embryos with an intact zona was higher in the encapsulated group than in the non‐encapsulated group (95.3% vs. 76.5%, P < 0.001). The encapsulation markedly reduced the occurrence of damage to the mucin coat (from 43.1% to 8.5%, P < 0.001). The frozen and thawed embryos that were released from alginate gel developed normally in vitro (86.3%) and in vivo (54.2%). The results suggest that encapsulation of rabbit embryos in alginate gel prior to freezing improves the percentage of transferable embryos after thawing and increases the number of offspring that originate from frozen and thawed embryos.
Comparative kinematic analysis of prey capture in Anolis carolinensis (iguania) and Lacerta viridis (scleroglossa)
Authors: Bels Vincent L. , Goosse Veronique
Published: June 2005

The kinematic profiles of jaw movements are described for Anolis carolinensis and Lacerta viridis feeding on the same prey item (maggot). A. carolinensis is an iguanian (typified by lingual prey capture) and L. viridis is a scleroglossan (typified by prey capture using jaws alone). A. carolinensis, however, catches maggots by using only the jaws. In so doing, it exhibits the four stages of gape profile considered typical for lizards (slow open, fast open, fast close, slow close). Gape cycle in L. viridis shows a hyperbolic curve (no slow open). Two hypotheses concerning the relationship between the two gape cycles are discussed.
Mobilization of lipid and protein by embryonic snapping turtles in wet and dry environments
Authors: Janzen Fredric J. , Packard Gary C. , Packard Mary J. , Boardman Thomas J. , Zumbrunnen James R.
Published: June 2005

Eggs of common snapping turtles (Chelydra serpentina) were incubated at 26°C on substrates with water potentials of – 150 kPa (wet) and – 850 kPa (dry) to assess the effects on patterns of mobilization of nutrients from the yolk. Embryos developing at – 150 kPa mobilized and incorporated both lipid and protein more rapidly than did embryos developing at – 850 kPa. As a consequence, embryos developing in wet environments hatched at a larger size than did embryos developing in dry settings. This effect of moisture on embryonic metabolism and growth in snapping turtles differs from that found in birds in which embryonic growth apparently is unaffected by moisture.
Photomanipulation of sexual maturation and breeding cycle of the steppe polecat (Mustela eversmanni) and other techniques for more rapid propagation of the species
Authors: Mead Rodney A. , Neirinckx Sandra
Published: June 2005

Twenty steppe polecats were divided into 2 groups, each consisting of 4 males and 6 females, and subjected to either a natural photoperiod (controls) or alternating periods of short (8 h light/16 hr dark for 8–9 weeks) and long days (16 h light/8 h dark for 16–20 weeks). The experimental photoperiod significantly accelerated sexual maturation in both sexes, with males developing maximal testis size within 57 days and females breeding after an average of 52 days exposure to 16L/8D. Males in the experimental group completed 2 1/2 testicular cycles and participated in mating during 3 successive breeding seasons during the 18 month period whereas males in the control group completed a single testicular cycle and only had an opportunity to mate during a single breeding season. Females in the experimental group produced 3 litters whereas females in the control group only gave birth to a single litter. Litter size averaged 6.9 ± 2.0 (n = 23) and did not significantly differ with age, parity, or treatment. Pseudopregnant females returned to estrus within 12 days after the expected date of parturition, were bred, and gave birth to kits. Polecats which were subjected to the experimental photoperiods completed more molting cycles and underwent more photoperiod‐induced changes in body weight than those in the control group.

Death or removal of kits within 8 days after birth resulted in 12/12 females returning to estrus within 6–26 days. Eleven of these females were remated and gave birth to kits. Eight domestic ferrets readily accepted neonatal polecat kits and 5 successfully reared kits, although kit survivial was quite poor. These results clearly demonstrate the potential of these techniques for inducing precocious sexual maturation and production of multiple litters each year.
Conserved tissue‐restricted expression of HUC 1‐1 actin phenotype among eumetazoan organisms
Authors: Sawtell N. M. , Hartman A. L. , Lessard J. L.
Published: June 2005

Actin has evolved from a single protein into a family of more than six distinct isoforms in mammals. Based on amino acid sequence data, actins segregate into two major classes, the “cytoplasmic” or nonmuscle actins, present in all animals, and the “α‐” or muscle actins, a group restricted to vertebrate muscle. We have recently identified two unique actin isoforms in rat intestinal brush border which combine features of these two classes. The amino terminal regions of these actins indicate that they are of a cytoplasmic type and yet the carboxy terminal regions contain an epitope (defined by Mab HUC 1‐1) which, among mammalian actins, is restricted to the muscle isoforms. We report here that in addition to the rat, all species thus far examined which have an intestinal “brush border” express actins containing the HUC 1‐1 epitope in this region. Furthermore, we show that the actins present in the muscle tissue of nonvertebrate eumetazoans, which are all of the cytoplasmic type, also contain this epitope. Thus these findings suggest that the HUC 1‐1 epitope appeared early on a subset of cytoplasmic‐type actins and was retained among actins expressed in muscle tissue throughout the evolutionary divergence of these cytoplasmic‐type actins to the “α‐” muscle actins.
Effects of prolactin and bromocryptine on the regulation of testicular luteinizing hormone receptors in mice
Authors: Takase Minoru , Tsutsui Kazuyoshi , Kawashima Seiichiro
Published: June 2005

The binding of luteinizing hormone (LH) to testicular homogenates increased gradually in mice from 15 to 60 days of age, while the level at 90 days was almost the same as that at 60 days. The plasma concentration of prolactin (PRL) increased significantly from 15 to 40 days and thereafter remained constant. In order to ascertain the influence of PRL on testicular receptors for LH, bromocryptine was injected subcutaneously for 10 days into immature (20‐day‐old) and adult (90‐day‐old) mice. In 20‐day‐old mice, treatment with bromocryptine significantly reduced the plasma levels of PRL but had no significant effects on the binding of LH to receptors in 30‐day‐old mice. However, in 90‐day‐old mice, treatment with bromocryptine led to a significant reduction in numbers of receptors for LH 10 days later. There was no difference in dissociation constants (Kd) between groups of oil‐injected (Kd = 6.5 × 10−10 M) and bromocryptine‐injected (Kd = 4.6 × 10−10 M) mice. The reduction in binding of LH per testis of 100‐day‐old mice after treatment with bromocryptine was eliminated by the simultaneous administration of ovine (o) PRL. The plasma level of follicle‐stimulating hormone (FSH) in 100‐day‐old mice, which tended to be decreased as a result of treatment with bromocryptine, was markedly increased by treatment with oPRL. There were no distinct changes in binding of FSH in any of the groups. These results suggest that, in immature mice, PRL is not the principal factor involved in the age‐related increase in numbers of receptors for LH while, in adult mice, PRL plays a stimulatory role in the increase in the number of these receptors.
Developmental potential of biopsied mouse blastocysts
Authors: Nijs Martine , Van Steirteghem André
Published: June 2005

The health of a preimplantation embryo can be diagnosed in one or more cells biopsied from the conceptus. Here, we tried to evaluate the impact of biopsy of some trophectoderm cells from hatching mouse blastocysts on their further in vitro implantation and early egg cylinder formation. Of 374 blastocysts evaluated 112 hours after hCG, 34% initiated hatching with a small number of mural, polar, or intermediate trophectoderm cells. Half of 59 embryos that underwent induction of hatching by zona puncturing herniated some cells through this opening. After removal of cells with a glass microneedle from spontaneously hatching blastocysts, viability assessed by vital FDA staining was impaired, as well as the in vitro zona pellucida shedding and implantation. When polar trophectoderm cells were biopsied, a significantly lower number of embryos reached the egg cylinder stage.
Role of body temperature in seasonal acclimatization: Photoperiod‐induced rhythms and heat production in Meriones crassus
Authors: Haim A. , Levi G.
Published: June 2005

Heat production by means of nonshivering thermogenesis (NST) and food consumption were compared in individuals of the fat jird Meriones crassus, acclimated to 8L:16D and 16L:8D cycles at an ambient temperature of 28°C. Daily rhythms of body temperature were compared at the same time.

A significant (P < 0.05 and P < 0.005) increase in NST and food consumption was noted in fat jirds acclimated to short photoperiod 8L:16D when compared with those acclimated to a long photoperiod 16L:8D. A clear difference in rhythms of body temperature was observed between the two groups.

In light of these results it is reasonable to assume that seasonal acclimatization in the fat jird can be partly induced by the change of photoperiod. Rhythms of body temperature in the fat jird are entrained by photoperiod and appear to be adjusted to the different metabolic demands of summer and winter.
Action of 1,25‐dihydroxyvitamin D3 and parathyroid hormone on 45calcium uptake by the yolk sac membrane of chick embryos
Authors: Lee S. K. , Clark N. B. , Brown S. C.
Published: June 2005

During development, the chick embryo mobilizes the calcium it needs from two extraembryonic sources, initially from the yolk and later from the eggshell. Calcium may be hormonally regulated during avian embryogenesis, but details of this regulation are lacking. We investigated the effects of 1,25‐dihydroxycholecalciferol [1,25(OH)2D3], bovine parathyroid hormone [bPTH], and vehicle [ethanol or saline] on blood calcium values and incorporation of 45Ca into the yolk sac membrane of 9, 12, and 15 day chick embryos. Control data were also collected from uninjected 6 day embryos. Solutions were injected directly into the yolk sac compartment 48 and 24 hours prior to the experiment. Exogenous 1,25(OH)2D3 induced hypercalcemia in all age groups examined, while exogenous PTH induced hypercalcemia in day 12 and 15 embryos. Small disks of yolk sac membrane were incubated in medium to which 45Ca was added and assayed for 45Ca content at various intervals after start of incubation. In control yolk sac tissue, the uptake of 45Ca was greatest in younger embryos with decreasing uptake at developmentally more advanced ages; 1,25(OH)2D3 treatment significantly enhanced the uptake of 45Ca into yolk sac tissue in all groups (9, 12, and 15 day embryos). PTH treatment caused a significant elevation in 45Ca uptake in the day 12 and 15 embryos.
Relative developmental abilities of hamster 2‐ and 8‐cell embryos cultured in hamster embryo culture medium‐1 and ‐2
Authors: Seshagiri Polani B. , Bavister Barry D.
Published: June 2005

The relative developmental abilities of hamster 2‐ and 8‐cell embryos in culture were compared using two versions of hamster embryo culture medium (HECM). These media differed primarily in the number of amino acids present, i.e., 20 amino acids in HECM‐1 and four amino acids in HECM‐2. When 2‐cell embryos were cultured for 24 h, the percentages of ⩾4‐cell embryos obtained in both HECM‐1 and HECM‐2 were comparable (≃93%); at the end of 48 h, the proportion of ⩾8‐cell embryos obtained in HECM‐1 (82.5%) was significantly (P ⩽ 0.001) more than that obtained in HECM‐2 (67.9%). Interchange of media, after 24 h culture, did not enhance the ability of cultured 2‐cell embryos to become blastocysts. When 8‐cell embryos were cultured for 18 h in HECM‐1 and ‐2, there was no appreciable difference in the proportion of total blastocysts formed (89‐91%). However, there were significantly (P ⩽ 0.001) more late blastocysts in HECM‐2 than in HECM‐1 (68.2% vs. 38.4%). Embryo development from 2‐ and 8‐cell stages was compared in media that differed by the presence and absence of phenol red and penicillin‐G. There was no difference in embryo development when these compounds were present or absent. Similarly, the difference in pyruvate concentration between HECM‐1 and ‐2 (0.5 and 0.2 mM, respectively) did not affect embryo development. These results show that a) the presence of four amino acids (Phe, Ile, Met, and Gln as in HECM‐2) was not sufficient for 2‐cell embryo development in culture and additional amino acids (as in HECM‐1) were required; and b) the four amino acids were better than 20 amino acids for obtaining late blastocysts starting from the 8‐cell stage. The low percentage of late blastocysts obtained in HECM‐1 was attributed to the presence of inhibitory amino acids in this formulation. Hence, it is concluded that the optimum medium for development of hamster embryos would contain <4 and >20 amino acids.
Glutathione effects Ciona intestinalis larval tunic morphogenesis
Authors: Robinson W. E. , Michibata H. , Kustin K. , Doona C. J.
Published: June 2005

Dechorionated neurulae and early tail‐bud embryos of Ciona intestinalis (Linnaeus) develop into tadpole larvae without fully formed dorsal, ventral, or caudal fins, although other aspects of organ and tissue development appear normal. Groups of dechorionated neurulae treated with the reducing agent glutathione exhibit a 5‐8% enhancement in caudal fin length compared with dechorionated controls. Other reducing substances tested, namely, gallic acid, chlorogenic acid, cysteine, and dithiothreitol, had no effect on fin formation, possibly due either to their rapid oxidation in aerated seawater (chlorogenic and gallic acids) or to kinetic inertness (dithiothreitol and cysteine). These results imply that larval fin morphogenesis requires secretion of a specific reducing substance.
Limb regeneration in juveniles of the mud crab Rhithropanopeus harrisii following removal of developing limb buds
Authors: McConaugha John R.
Published: June 2005

Regeneration of autotomized limbs by third crab stage Rhithropanoepus harrisii followed the all‐or‐none rule and was completed without significant alteration of the normal molt cycle. Loss of three to six primary limb buds during late intermolt or early premolt (D0, day 3) resulted in a delay of ecdysis while secondary limb buds were formed. The number of animals delaying ecdysis and producing secondary buds was stimulus dependent. While the number of animals initiating secondary regeneration increased with the number of primary buds lost, fewer animals in these groups were capable of regenerating all of the missing primary buds. Animals not initiating secondary regeneration or regenerating only some of the primary limb buds completed regeneration during the following molt cycle. The duration of the subsequent molt cycle was significantly shorter for all regenerating animals, including the regeneration control group. Partial regeneration and acceleration of subsequent molts appears to be the best allocation of available energy reserves.
Changes in the function of dermal fibroblasts in the tadpole tail during anuran metamorphosis
Authors: Kinoshita Tsutomu , Takahama Hideki , Sasaki Fumie
Published: June 2005

The role of the fibroblast in the degeneration of the dermal collagen layers was examined in the tail skin of Rana japonica during metamorphosis. At the early stages of tail resorption, spindle‐shaped fibroblasts, which had been staying beneath a dermal collagen layer, began to put out numerous cytoplasmic processes and to invade the collagen layers. As degeneration of the tail progressed, invading cells within the dermis seemingly increased in number. However, quantitative data concerning cell density within the dermis showed that remarkable cell migration other than invasion of fibroblasts does not occur in the dermis until the final stage of metamorphosis. Ultrastructural analyses by staining with ruthenium red and cytochemical localization of acid phosphatase supported a possibility that dermal collagen fibers are intracellularly digested in the invading fibroblasts. In order to confirm the ultrastructural observation that phagocytes of collagen fibers are fibroblasts, constituent cells of tail skin were characterized with isolectin GS‐1, from Griffonia simplicifolia, directly labeled with colloidal gold. In normal tail skin, GS‐1 bound to the free surface of the epidermis, macrophages, and neutrophils, but not to dermal fibroblasts at all. Binding of GS‐1 was also not found on the collagen‐phagocytosing cells in the degenerating skin. Thus, analysis with GS‐1 lectin was consistent with ultrastructural results. These results suggest that phagocytes of collagen fibers in the degenerating tail are fibroblasts and/or fibroblast‐derived cells and that dermal fibroblasts in the tail change in function to become collagen‐phagocytosing cells during metamorphosis.
Reproduction, pregnancy, and circulating reproductive hormones in the lactating siberian hamster (Phodopus sungorus)
Authors: Parkening T. A. , Collins T. J.
Published: June 2005

The Siberian hamster (Phodopus sungorus) has a post‐partum estrus in which it may mate, ovulate, and become pregnant. The pregnancy proceeds as a normal pregnancy while suckling young. Delayed implantation does not exist in this species. If the female fails to become pregnant during the post‐partum estrus, at least one and possibly two other estrous cycles follow in which she may mate and become pregnant. Of 88 litters born after the first litter from 20 pairs of Siberian hamsters during their reproductive life span the days elapsing/mean number of young (± SEM) were as follows: 18–23 days (5.85 ± 0.3, n = 33), 24–29 (5.16 ± 0.4, n = 19), 30–35 (4.25 ± 0.6, n = 8), 40–49 (4.33 ± 0.4, n = 16), 50–52 (5.80 ± 1.0, n = 5), 62–65 (4.00 ± 1.2, n = 3), 70–78 (2.75 ± 0.6, n = 4). No correlation could be found between the number of young nursing and the number of days between litters.

Circulating plasma levels of progesterone (P), prolactin (Prl), luteinizing hormone (LH), and follicle‐stimulating hormone (FSH) were radioimmunoassayed from lactating pregnant and non‐pregnant Siberian hamsters and from lactating Syrian and Chinese hamsters at 2, 5, 10, and 15 days post‐partum. At 5 days post‐partum, both pregnant and non‐pregnant Siberian hamsters exhibited significantly higher levels of P than Syrian or Chinese hamsters. Prl levels were significantly lower in Siberian hamsters at 2 and 5 days post‐partum when compared with those in Syrian hamsters. Selected rank‐order comparisons showed a strong negative correlation (P<.001) between P and Prl for pregnant lactating Siberian hamsters.
Effect of egg water from Bufo arenarum on the fertilizing capacity of homologous spermatozoa
Authors: Fontdevila Marina F. Díaz , Bloj Bernabé , Cabada Marcelo O.
Published: June 2005

The effect of egg water (EW) from oocytes' string of Bufo arenarum on the fertilizing capacity of homologous spermatozoa was studied. When Bufo arenarum spermatozoa were incubated in EW, a decrease in the fertilizing capacity of spermatozoa was observed. This effect depended on the osmolarity of the incubation medium. When the osmolarity was between 35 and 40 mOsm/kg water, inhibition of fertility was observed even in the presence of only 10% EW. When osmolarity was greater than 60 mOsm/kg water, even 90% EW had no effect. Control spermatozoa incubated in saline medium with osmolarity similar to that of EW did not show any decrease in fertility. These effects seem to be related to a component of the EW that can be extracted with agents used to extract lipids. The effect of such lipidic extracts of egg water (LEEW) in reducing the fertilizing capacity of a sperm suspension depends on the concentration of LEEW and the duration of incubation.
Effect of photoperiod on the rate of 3H‐thymidine incorporation of epididymal principal cells in adult Syrian hamsters
Authors: Johnson Larry , Bartke Andrzej
Published: June 2005

Photoperiod‐induced cycles of gonadal regression and recrudescence in the Syrian hamster were used to determine if epididymal growth in adults involves mitotic activity of principal cells. In Experiment 1, the following groups of adult hamsters were examined: induced recrudescing (5L:19D [5 hr light and 19 hr dark] for 13 wk followed by 14L:10D for at least 3 wk), spontaneous recrudescing (5L:19D for 25 wk), and active gonadal state (14:10D). In Experiment 2, adult hamsters were divided into the following groups: induced recrudescing, active, and regressed (5L:19D for 16 wk). Hamsters received subcutaneous injections of 0.5 μCi 3H‐thymidine/g body weight three times/wk for 3 wk. The epididymis was fixed in a glutaraldehyde followed by osmium, embedded in Epon 812, and sectioned at 1 μm. Slides were dipped in Kodak NTB‐3 emulsion, exposed for 2 or 3 months, developed, and evaluated for isotopic labeling of principal and basal cell nuclei by scoring 500 to 1,000 nuclei. In Experiment 1, the percentages of labeled principal cell nuclei for the induced recrudescing, spontaneous recrudescing, and active groups were 26 ± 2%, 23 ± 5%, and 9 ± 1%, respectively. Considering the intermittent availability of 3H‐thymidine during 21 days, this represents daily recruitment of 6.3%, 5.6%, and 2.2%, respectively. In Experiment 2, the percentages of labeled principal cell nuclei for induced recrudescing, active, and regressed groups were 12 ± 4%, 3 ± 1%, and 4 ± 1%, respectively. There was no effect of photoperiod on labeling pattern of basal cells (1.5 ± 0.6%, 1.2 ± 0.1%, 0.4 ± 0.1% for the three photoperiod groups, respectively). Regardless of photoperiod, there was no difference in the labeling pattern of principal or basal cells between the head and the tail of the epididymis. In conclusion, photoperiod influenced the recruitment of epididymal principal cells throughout the epididymis, and new principal cells were added continually to the existing population of cells even in gonadally active adult hamsters.
Nematocyst discharge in Hydra does not require the presence of nerve cells
Authors: Aerne Birgit L. , Stidwill Robert P. , Tardent Pierre
Published: June 2005

By parabiosis we have constructed Hydra that lack nerve cells but whose tentacles contain nematocytes (stinging cells). We were able to demonstrate that the nematocysts of these polyps can be triggered either mechanically or electrically. We conclude that nematocyst discharge in hydra does not require the presence of nerve cells.
Internalization of erythrocytes into liver parenchymal cells in naturally hibernating frogs (Rana esculenta L.)
Authors: Barni Sergio , Bernocchi Graziella
Published: June 2005

Mature and intact red blood cells were found in hepatocytes of frogs during natural underground hibernation. No signs of erythrophagocytosis, e.g., separating membranes between erythrocyte and hepatocyte cytoplasm, and lysosomes, were observed. Red blood cells probably penetrated into hepatocytes by ameboid‐like mechanisms, which can be deduced by cytoplasmic protrusions and invaginations. Most of the hepatocytes had large amounts of stored glycogen and few organells, often segregated in condensed areas. The narrowed bile canalicular lumens without lysosomes and exocytotic vacuoles around them and the reduction of the Disse spaces indicate a low metabolic activity of liver during natural hibernation. The dramatic accumulation of red cells in the hepatocytes of hibernating frogs could share similarities with the phenomenon of internalization of leucocytes into epithelial cells of some vertebrate's tissues via emperipolesis, the mechanisms of which are not well understood.
Adenylate cyclase activity in Mytilus galloprovincialis Lmk: Characteristics of the enzyme from mantle tissue
Authors: Mancebo M. J. , Treviño M. , Crespo C. A. , Espinosa J.
Published: June 2005

The presence and characteristics of a membrane‐bound adenylate cyclase from Mytilus galloprovincialis mantle tissue has been investigated. Enzymatic activity was measured using α32P‐ATP as the substrate with chromatographic isolation of the 32P‐cAMP formed. The enzyme has a Km for ATP of 0.35 mM at 20°C and requires divalent cations (Mg2+ /Mn2+) for its activity. Optimal GTP concentrations are between 10−6 M and 10−4 M. The non‐hydrolyzable GTP analogs, GTPpNHp and GTPγS, increase the activity of the enzyme two‐ to fourfold. NaF stimulates the enzymatic activity ten‐ to 20‐fold. An inhibition of basal activity by adenosine was observed.
Incorporation of strontium (90Sr2+) into the skeleton of the hermatypic coral Galaxea fascicularis
Authors: Ip Y. K. , Krishnaveni P.
Published: June 2005

The rate of 90Sr2+ deposition in Galaxea fascicularis was linear with respect to Sr2+ concentration (0.01–20 mM) and refractory to DCMU (1 μM), an inhibitor of photosynthesis. The deposition rate of 90Sr2+ in polyps incubated under a light intensity of 200 μE.m−2 s−2 was not significantly different from that in polyps incubated in total darkness. The deposition rate of 45Ca2+ (1–20 μM), on the other hand, exhibited saturation kinetics. In addition, it was DCMU sensitive and enhanced by light. Our results therefore support observations reported elsewhere that KsrA is inversely correlated with growth rate in reef corals. However, Sr2+ and Ca2+ deposition in G. fascicularis does not appear to involve similar biochemical mechanisms.
Renal clearance of phosphate and calcium in vitamina D‐deficient chicks: Effect of calcium loading, parathyroidectomy, and parathyroid hormone administration
Authors: Clark Nancy B.
Published: June 2005

Serum and renal clearance values of phosphate and calcium were measured and compared in 4 week‐old vitamin D‐deficient and vitamin D‐replete chickens (Gallus gallus). D‐deficient chicks had significantly lower body weights and serum calcium values; however, their renal functions were not different from D‐replete controls. Serum calcium values in D‐deficient birds did not change in response to parathyroid hormone (PTH) administration; however, they did drop significantly in response to parathyroidectomy (PTX). Serum phosphate values of D‐deficient birds, but not D‐replete birds, rose significantly after PTX.

Clearance of phosphate is known to increase after administration of PTH. This conspicuous effect was absent in PTH‐injected vitamin D‐deficient chickens. PTX caused the excretion of phosphate to drop in both D‐deficient and D‐replete birds to near zero. Conversely, PTX of both D‐deficient and D‐replete chickens stimulated the excretion of more calcium than in controls.

Calcium loading elevates the fractional excretion of calcium in both D‐deficient and D‐replete birds. It also causes a decrease in phosphate excretion in both groups, presumably by inhibiting the secretion of PTH. PTH administration of D‐replete, calcium‐loaded birds caused increased phosphate excretion (as it did in normal controls), an effect that was not seen in similarly treated D‐deficient birds.

Therefore most renal functions studied after calcium loading, PTH administration, or PTX are not altered by vitamin D deficiency in the chicken. The major significant finding is that vitamin D‐deficient chickens do not excrete increased amounts of phosphate in response to PTH stimulus.
Thyroid hormone stimulates the shift of erythrocyte populations during metamorphosis of the flounder
Authors: Miwa Satoshi , Inui Yasuo
Published: June 2005

Hormonal control of changes in circulating erythrocytes was studied in the metamorphosing flounder (Paralichthys olivaceus). Premetamorphic flounder larvae had large, round erythrocytes with small, round and pyknotic nuclei. At metamorphic climax, many smaller erythroid cells with larger nuclei appeared in the circulation. These cells developed into elliptical, adult‐type erythrocytes in fully metamorphosed juveniles. Larval erythrocytes were not observed in juvenile fish. Biochemical analysis of hemoglobins are different between larvae and juveniles. L‐thyroxine (T4) treatment at 100 ppb in ambient seawater clearly stimulated a precocious morphological shift in the erythrocyte populations within 15 days, while the predominant blood cells in control fish were the larval erythrocytes throughout the experiment. The erythrocyte shift found in T4‐treated larvae coincided with metamorphic changes in external appearance and behavior of the fish. These results indicate the presence of the two distinct populations of erythroid cells, larval type and adult type, in developing flounder larvae, and suggest that thyroid hormone suppresses larval erythropoiesis and stimulates establishment of adult, or definitive erythropoiesis.
Increased content of inositol phosphates in amputated limbs of axolotl larvae, and the effect of beryllium
Authors: Tsonis Panagiotis A. , English Denis , Mescher Anthony L.
Published: June 2005

The involvement of phosphatidylinositol phosphate (PIP) breakdown in the initiation of cell proliferation, differentiation, or other developmental processes is well established. PIP breakdown leads to the formation of second messengers, including inositol trisphosphate, which evoke cellular responses and cell‐to‐cell interactions. Such events occur very early after exposure of cells to an agonist. In an attempt to elucidate biochemical mechanisms that could be involved in stimulating cellular events during very early stages of vertebrate limb regeneration we examined local production of inositol phosphates (IPs) following amputation axolotl limbs. The content of IPs increases in stump tissues within 30 seconds after amputation. In addition we found that beryllium treatment, which inhibits regeneration if applied to stumps immediately after amputation, blocks production of IPs. Similarly, Li+ which is known to inhibit production of IP3 affected regeneration in a similar fashion to beryllium. These results indicate that production of PIP‐derived second messengers is one of the earliest events following amputation and might be crucial for the regeneration process.
Regulation of proline synthesis in osmotic response: Effects of protein synthesis inhibitors
Authors: Burton Ronald S.
Published: June 2005

Like many euryhaline marine invertebrates, the copepod Tigriopus californicus acclimates to changes in environmental salinity by adjusting intracellular concentrations of free amino acids (FAA). Proline and alanine are the primary contributors to the FAA pool, and previous work has shown that synthesis of the former is specifically induced by hyperosmotic stress. To determine if protein synthesis plays a regulatory role in the accumulation of FAA during hyperosmotic stress, T. californicus were exposed to two protein synthesis inhibitors prior to and during transfer from 50% to 100% seawater. Both inhibitors, cycloheximide and anisomycin, were found to sharply reduce proline synthesis during hyperosmotic stress. By providing 14C‐(U)‐L‐glutamate as a proline precursor, evidence was obtained that the ultimate site of action for the inhibitors was in the three‐step pathway between glutamate and proline. This work suggests that hyperosmotic stress induces the synthesis of one or more of the enzymes in the proline biosynthetic pathway or a protein which functions to stimulate the activity of these enzymes.
Cleavage rates of diploid and tetraploid mouse embryos during the preimplantation period
Authors: Henery C. , Kaufman M. H.
Published: June 2005

Despite the fact that spontaneous tetraploidy is a rare phenomenon in mice, such embryos may be produced experimentally by a variety of means, though only a very limited degree of postimplantation development has been achieved. Despite this apparent limitation, much data on the rate of development of preimplantation tetraploid embryos has been published. However, the findings from these studies has often been conflicting. In the light of the recent successful achievement of advanced postimplantation tetraploid development in our laboratory, we decided it was an opportune time to re‐evaluate the preimplantation development of these embryos in as near to optimal conditions as we could achieve.

Three groups were studied, namely 1) control (diploid) embryos developing in vivo, 2) control (diploid) embryos that had been isolated at the 2‐cell stage, briefly retained in culture, then transferred to the oviducts of pseudopregnant recipients, and 3) tetraploid embryos produced by electrofusion of blastomeres at the 2‐cell stage, then transferred to the oviducts of pseudopregnant recipients. Embryos were isolated from females from each group at specific times after the HCG injection to induce ovulation. The total cell number of each embryo was established and the log mean values were plotted against time. From the gradients of the lines it was possible to establish that there was a significant difference between the cell doubling time of the transferred controls (group 2) compared to the in vivo controls (group 1) with cell doubling times of 15.86 ± 1.45 h and 10.27 ± 0.24 h, respectively. However, there was no significant difference between the cell doubling time of the tetraploids and the transferred controls (group 2), with the tetraploids having a cell doubling time of 14.87 ± 0.54 h. The results therefore show that under matched experimental conditions, tetraploid mouse embryos develop during the preimplantation period at the same rate as diploids despite their reduced cell number. This finding suggests that the various hypotheses that have been proposed to explain the poor postimplantation development of tetraploids, related principally to their supposed poorer proliferative activity than controls, does not appear to be applicable at least in relation to their preimplantation development.
Enzyme activities and antifungal action of fertilization envelope extract from fish eggs
Authors: Kudo Shigeharu , Teshima Chisato
Published: June 2005

Extracts from fertilization envelopes (FE) of activated eggs of two species of fish, Plecoglossus altivelis and Tribolodon hakonensis, have been demonstrated to contain carboxymethylcellulase, carboxymethylchitinase, β‐1,3‐glucanase (or laminaranase), lichenase, xylanase, dextranase, mannase, protease, and lysozyme activities by an agar plate method. Vitelline envelope (VE) extracts in contrast had no enzyme activities. The FE extracts exerted an antifungal or fungicidal action on the fungus Saprolegnia parasitica which was isolated from the body surface of a carp with mycosis. Inhibition of hyphal growth from the mycelial pieces was time‐dependent. The VE extracts had no antifungal action. FE extracts treated with pronase exerted no antifungal or fungicidal action on S. parasitica, but trypsinized FE extracts still retained their antifungal or fungicidal effect. These results suggest that the FE may be able to protect the embryo through enzymatic activity, which is acquired after the process of cortical reaction, and may help to degrade the cell walls of potential pathogens.
Role of cryophase temperature and thermophase duration in thermoperiodic regulation of the testicular cycle in the lizard Lacerta vivipara
Authors: Gavaud Jacqueline
Published: June 2005

Testicular activity in reptiles is controlled primarily by thermal and thermoperiodic factors; however, little is known about the relative contribution of daily heating and nightly cooling in these processes. This question was addressed in the lizard Lacerta vivipara whose cycle is characterized by a 6 month hibernation followed by a single spring spermiogenesis and a summer spermatogenesis. From the autumnal equinox on, lizards were maintained under a constant 12L/12D photoperiod and acclimated to different 24 hour thermoperiodic regimes. Treatments combined a short or a long thermophase (2 or 6 hr basking) in alternation with either a warmer (19–21°C) or a colder cryophase (3–7°C). Testicular activity was monitored by histological examination of the testis and epididymis in late December and in early March. Heat provided daily during either 2 or 6 hour phases advanced spermiogenesis and spermiation by 3–4 months. Cryophase temperatures had no significant effects on the date of onset of spermiogenesis whereas they greatly affected its speed of completion. Thus, the full testicular cycle, from one spermatogenetic wave to the next, was completed within 6 months under warmer cryophases alternating with either long or short thermophases. In contrast, only part of the cycle was completed in lizards experiencing colder cryophases since active spermiogenesis and spermiation were maintained for at least 2 months as under natural conditions. The functional significance of heat and cold per 24 hour cycles in the regulation of the testicular cycle is discussed.
Peroxisomal β‐oxidation: Insights from comparative biochemistry
Authors: Moyes Christopher D. , Suarez Raul K. , Brown Gayle S. , Hochachka Peter W.
Published: June 2005

The activities of fatty acyl‐CoA oxidase (FAO) and carnitine palmitoyl transferase (CPT), indices of the capacities of peroxisomal β‐oxidation and mitochondrial β‐oxidation, respectively, were determined in livers of several vertebrate species notable for differences in dietary fatty acid composition. In suckling rats FAO activities were half that in adult rats and CPT/FAO ratios twice that of adult rats. As their milk diet is dominated by medium chain fatty acids, this observation is consistent with current ideas about the role of peroxisomal β‐oxidation in rat liver in oxidation of long chain unsaturated fatty acids. In nectar‐feeding hummingbirds (fatty acids synthesized de novo) FAO activities were 50% greater than adult rats and CPT/FAO ratios onethird less than adult rats, suggesting that peroxisomal β‐oxidation is relatively more important in this species, despite a fatty‐acid‐poor diet. In marine fish (herring, dogfish shark, hagfish) FAO activities were all less than 15% that of rats and undetectable in hagfish. CPT/FAO ratios were greater in herring (8.1) and hagfish (> 30) than adult rats (3.1), suggesting that peroxisomal β‐oxidation is relatively less important in these species despite a natural diet containing high levels of long chain polyunsaturated fatty acids. These data are discussed in relation to current ideas about the role of peroxisomes in β‐oxidation of fatty acids.
Chemical repellency in birds: Relationship between chemical structure and avoidance response
Authors: Clark Larry , Shah Pankaj S. , Mason J. Russell
Published: June 2005

We examined how molecular structure of 24 anthranilate and benzoic acid derivatives correlated with drinking behavior in European starlings Sturnus vulgaris. The effectiveness of bird repellents was associated with basicity, the presence of an electron‐donating group in resonance with an electron‐withdrawing carboxylic group on a phenyl ring, and a heterocyclic ring in the same pi cloud plane as the phenyl ring. Of the benzoic acid derivatives tested in this study, methyl, ethyl, dimethyl, and linalyl anthranilate as well as anthranilic acid and 4‐ketobenztriazine were repellent to birds. Water consumption was significantly reduced relative to control levels at concentrations as low as 0.05% (weight/volume) for the best repellents. Further statistical tests showed that reduction in consumption for the best repellents was absolute, not significantly different from zero consumption. Anthranilic acid isomers were moderately good repellents. The ability to generate a model predicting repellency allows for the efficient identification and development of ecologically sound, nonlethal, taxa‐specific repellents to be used for the protection of wildlife in agricultural and industrial applications.
Genetic analysis of androgenetic rainbow trout
Authors: Scheerer Paul D. , Thorgaard Gary H. , Allendorf Fred W.
Published: June 2005

We analyzed a number of genetic characteristics in androgenetic rainbow trout (Oncorhynchus mykiss) and their progeny. The androgenetic progeny of individual androgenetic males appeared genetically identical to each other based on eight enzyme loci. Their viability was no higher than that of androgenetic progeny of outbred males. Homozygous androgenetic female rainbow trout produced very poor quality eggs. When common eggs and sperm from outbred individuals were used to produce androgenetic and gynogenetic progeny, the yield of gynogenetic progeny was higher but some were heterozygous at protein loci, while no androgenetic progeny were heterozygous. Some androgenetic diploid rainbow trout were successfully produced from cryopreserved sperm. The progeny of some androgenetic males crossed to normal females were virtually all males, while the progeny of other males were virtually all females. This suggests that both XX and YY androgenetic individuals may develop as males. Androgenesis is likely to be useful for generating homozygous clones for research and for recovering strains from cryopreserved sperm.
Proliferation of lymphocyte‐like cells from the solitary tunicate, Styela clava, in response to allogeneic stimuli
Authors: Raftos D. A. , Cooper E. L.
Published: June 2005

Lymphocyte‐like hemocytes (LLCs) of solitary tunicates proliferate in response to allogeneic stimuli. In vitro labeling of proliferative hemocytes from the solitary species Styela clava revealed significantly greater proliferative activity among individuals immunized with allogeneic tissue as opposed to autogeneically primed and naïve animals. Enhanced proliferation was restricted to discrete crypts of dividing cells within the body wall of recipients. Here, increased proliferative activity was specifically associated with LLCs. These data support previous results which implicated LLC activity with immunological memory that is evident in allograft rejection. Hence, it is postulated that adaptive histoincompatibility responses in solitary tunicates depend upon the specific proliferation of immunocompetent cells.
On the convergent cell movements of gastrulation in Fundulus
Authors: Trinkaus J. P. , Trinkaus Madeleine , Fink Rachel D.
Published: June 2005

Mainly because of its transparency, the Fundulus gastrula constitutes ideal material for direct study of morphogenetic cell movements in vivo. Marking studies show that deep cells of the germ ring converge toward and enter the embryonic shield, where they undergo extension. Those close to the shield move faster. Analysis of videotapes reveals that all deep cells of the dorsal germ ring move toward the shield. But none moves in a direct line. All meander considerably. Germ ring cells nearer the shield move toward it at a higher net rate than those farther away because they meander less. This suggests that exogenous factors promote their directionality. Cells in the prospective yolk sac adjacent to the germ ring also show net convergence, but they meander more. Directional forces are apparently stronger in the germ ring.

Converging deep cells move both by filolamellipodia and, less frequently, by blebs. However, there is very little individual cell movement; all cells are almost always in adhesive contact with other cells in moving cell clusters. Clusters vary constantly in size, continually aggregating with other cells and other clusters and splitting. Filolamellipodial cells show contact inhibition of cell movement. Nevertheless, they move and do so directionally, presumably in part because, as members of cell clusters, much of their movement is passive. They also show intercalation or invasive activity, but, consistent with their contact‐inhibiting properties, only when neighboring cells separate and provide free space. Cells moving by blebbing locomotion are non‐contact inhibiting and intercalate readily. Cell division continues during convergence. Although this temporarily arrests their movement, the daughter cells soon join in the mass convergent movement.
Gonadotropin‐releasing hormone in the molly Poecilia latipinna: Molecular form, quantity, and location
Authors: Coe Imogen R. , Grier Harry J. , Sherwood Nancy M.
Published: June 2005

The molecular forms of gonadotropin‐releasing hormone (GnRH) present within the brain of the teleost Poecilia latipinna were characterized using high‐performance liquid chromatography (HPLC) and radioimmunoassay (RIA). The forms present appear to be similar to the previously identified forms of salmon GnRH and chicken GnRH‐II. Immunocytochemical studies showed the presence of GnRH‐immunoreactive cells in the posterior ventral telencephalon, preoptic area, and midbrain tegmentum. One male fish possessed immunoreactive cells in the nucleus glomerulosus, an area which has not previously been reported to contain GnRH containing cells. GnRH fibers were found extensively throughout the brain, located within the telencephalon, the optic tectum, the hypothalamus, and the midbrain. © 1992 Wiley‐Liss, Inc.