bluuebunny/crossref_metadata_2025 huggingface dataset:
A histological examination of the pars distalis from the syrian hamster mutant anophthalmic white (Wh)
Authors: James Susan C. , Asher Jr. James H.
Published: June 2005

The gene, Wh, causing anophthalmia in the Syrian hamster, Mesocricetus auratus, is a highly pleiotropic gene which has profound effects upon eye development, pigmentation, and reproduction. Hamsters homozygous for this gene also possess abnormalities in testicular size and composition which may be related solely to the lack of the visual pathway acting by means of altered pituitary function. The objective of this study was to determine whether morphological abnormalities existed in hypophyses of male hamsters homozygous for the mutant gene Wh. Accordingly, hypophyses from 10 normal, 10 heterozygous, 10 homozygous mutant, and 5 normal enucleated animals from the AN/As‐Wh strain were compared at the light and electron microscopic level. At the light microscopic level, glands from anophthalmic individuals contained 33% fewer cells and many of the cells present either resembled signet ring cells or folliculostellate cells. At the electron microscopic level, many cells from Wh homozygotes were greatly enlarged, contained only a few organelles and few to no secretory granules. In addition to the glandular cell types, agranular follicular cells were prevalent. Cells with numerous cilia, basal bodies, and a 9 + 2 microtubule configuration were also found within mutant glands. Since pituitaries from hamsters homozygous for Wh displayed far different morphological characteristics than did pituitaries from normal, heterozygous, or normal enucleated animals, it is postulated that either the gene (Wh) acts to alter cellular differentiation of the embryonic hyophysis or that the gene causes abnormal dedifferentiation in the adult.
Temperature‐sensitive periods of sex determination in emydid turtles
Authors: Bull J. J. , Vogt R. C.
Published: June 2005

In many turtles sex differentiation is controlled by the incubation temperature of the embryo, with low temperatures producing males, high temperatures producing females. This study investigates the developmental period of temperature‐sensitivity in two species of emydid turtles, using different combinations of incubation at a male‐determining temperature (25°C) and at a female‐determining temperature (31°C). The sensitive period extends throughout much of the middle third of development. Sex is more readily influenced by 25° than by 31°, however, so that maleness can be determined much earlier in development than can femaleness. Comparison of these results with a previous study of snapping turtles indicates that the sensitive period occupies somewhat the same developmental interval in these different turtles. However, in snapping turtles, the female‐determining temperature used (30°) is more influential than the male‐determining temperature (26°), in contrast with these results from emydids.
Suppression of first cleavage in the mexican axolotl (Ambystoma mexicanum) by heat shock or hydrostatic pressure
Authors: Gillespie Laura L. , Armstrong John B.
Published: June 2005

Androgenetic diploid axolotls were produced by ultraviolet inactivation of the egg pronucleus shortly after fertilization, followed by suppression of the first cleavage division by hydrostatic pressure or heat shock. After treatment at 14,000 psi for 8 minutes, diploidy was restored in 74% of the embryos, but only 0.8% survived to hatching. A 36–37° C heat shock of 10‐minutes duration, applied 5.5 hours after the eggs were collected, yielded a slightly lower percentage of diploids. However, the proportion surviving to hatching was significantly greater (up to 4.6%). A second generation of androgenetic diploids was produced from one of the oldest of the first generation males with a similar degree of success. The lack of significant improvement suggests that the low survival is due to the heat shock per se and not to the uncovering of recessive lethal genes carried by the parent.
Glucose transport across ocular barriers of the spiny dogfish, Squalus acanthias
Authors: Dimattio Joseph , Zadunaisky Joseph A.
Published: June 2005

Evidence is presented demonstrating that in the dogfish, Squalus acanthias, D‐glucose is transported from the blood to the ocular fluid compartments by a mechanism that is consistent with carrier‐facilitated transport. Across the dogfish aqueous barrier D‐glucose is transported 8.4 times faster than L‐glucose, whereas this D/L transport ratio is only 5.5 in the rat. Similarly, the D/L transport ratio is 12.7 across the dogfish vitreous barrier and only 6.1 across this barrier in the rat. It is estimated that per unit area of vitreous barrier, the rat transports D‐glucose faster than the dogfish but also has a greater passive permeability, as measured by L‐glucose, and transport is therefore less efficient. Urea transport was found to be faster than L‐glucose transport, suggesting a transport mechanism for urea other than simple diffusion. The sectional analysis of frozen vitreous humor indicated that the lens of the dogfish is supplied with D‐glucose from both the ciliary epithelium and across the retinal pigment epithelium, while the retina receives D‐glucose primarily across the pigment epithelium.
Involvement of the circadian system in photoperiodic regulation of insect antifreeze proteins
Authors: Horwath Kathleen L. , Duman John G.
Published: June 2005

Several species of insects produce proteins in the winter that depress the hemolymph freezing and supercooling points thereby functioning as antifreezes. These proteins produce a thermal hysteresis (difference between the freezing and melting points). This study concerns the environmental and physiological mechanisms that regulate the seasonal production of antifreeze proteins in the beetle, Dendroides canadensis. Larvae collected in early fall from a natural population and acclimated to a short photoperiod (8L/16D at 20°C, 90% RH) elevated levels of thermal hysteresis proteins (THPs), whereas those individuals maintained on a long (16L/8D) photoperiod did not. “Resonance” experiments showed that circadian rhythmicity is involved in the photoperiodic timing mechanism used by Dendroides to control antifreeze production. These results suggest that an important aspect of insect seasonality ‐ i.e., winter hardening ‐ includes complex biological timing processes of circadian nature.
Morphogenetic movements and fate map of the cypriniform teleost, Catostomus commersoni (lacepede)
Authors: Ballard William W.
Published: June 2005

The morphogenetic movements of Catostomus commersoni have been charted from the onset of epiboly to the envelopment of the yolk, by means of chalk markers implanted among the moving blastomeres. A fate map has been worked out for the late cleavage stage just before start of the patterned movements. Results from this species are compared with those for Salmo gairdneri which is a member of a different superorder and is the only other teleost for which the morphogenetic movements are known in detail. Eggs of the two species differ markedly in size, yolk content, and rates of cell movement, but they accomplish the assemblage of their organ systems in the same general way, with no more differences than are known within the group of urodeles, or of anura. Their fate maps are three‐dimensional and closely alike, and markedly different from those of other vertebrates, even of chondrostean fishes. The uniquely teleostean combination of features includes the early bipolar differentiation, the enclosure of the liquid yolk in a syncytial layer, the nonparticipation of the precociously formed surface epithelium in major organ formation, and the three‐dimensional sorting out of the germ layers by different tendencies of cell migration associated with blastomeres lying at different depths in the early blastodisc, as well as other wellknown peculiarities of organogenesis. The question remains whether all teleosts follow the path of Salmo and Catostomus, but these two point to major innovations in early embryonic development at some time during teleostean evolution.
Formation of the leg neuromuscular system in embryos of the cockroach, Periplaneta americana: I. Light microscope studies
Authors: Denburg Jeffrey L. , Fülöp Zoltán
Published: June 2005

Embryos of the cockroach, Periplaneta americana, were examined each day of their 32‐day developmental period. The interval between the first detection of leg rudiments and hatching was divided into 18 stages defined by a characteristic external morphology. Embryos of stages 1, 2, 3, 6, and 8, corresponding approximately to 6½, 7½, 9¼, 11, and 15 days of age, respectively, were examined in detail for changes in external leg morphology, development of thoracic ganglia and leg muscles, and the formation of connections between the two. These observations were based on a light microscopic analysis of serial sections through three different planes. A proximal distal gradient of muscle development within the leg was observed, the cellular events of which were described. The formation of connections between neurons in the thoracic ganglia and cells in the leg was inferred from observations of the extent of axon growth and the state of differentiation of the cells. The innervation of the coxal muscles may occur as early as stage 6. The role of pioneer neurons, sheath cell and body epithelium in guiding axon growth is discussed. The information in this report will serve as a guide in subsequent more detailed electron microscopic studies.
Viability under the testis capsule of inner cell masses isolated from TOr/TOr mouse embryos
Authors: Fujimoto H. , Yanagisawa K. O. , Urushihara Hideko
Published: June 2005

Single inner cell masses (ICM) isolated by immunosurgery from late blastocysts were able to develop into benign teratomas under the testis capsule after 1 month with a frequency of 76%. This technique was used to examine viability and developmental potency of embryos homozygous for the TOr mutation. The number of teratomas formed by the ICMs derived from TOr/+ × TOr/+ crosses was consistent with what is expected if TOr/TOr ICMs did not produce them. After ectopic culture for a short period, presumed TOr/TOr ICMs gave rise to abnormal spherical structures resembling embryonic parts of the mutant embryos at the egg cylinder stage. These results suggest that TOr/TOr ICMs have greatly decreased competency for developmental potency.
Axonal guidance in the neuroepithelium of the tail of the trout Salmo gairdneri
Authors: Geraudie Jacqueline , Singer Marcus
Published: June 2005

Axonal growth has been studied in the ependyma of the developing trout tail. Results of the ultrastructural investigation show that intercellular spaces or channels develop in advance of the growth of the pioneering neurites. This developmental process is reminiscent of the axonal patterning described in the growing ependyma of the newt. It gives some additional support to the “blueprint hypothesis” as presented by some of us (Singer et al., '79), which assign to the glial cells “the pattern of the primary neuronal pathways”.
Lung phospholipids in the embryonic and immature chicken: Changes in lipid composition and biosynthesis during maturation of the surfactant system
Authors: Hylka Vincent W. , Doneen Byron A.
Published: June 2005

Total phospholipid and its components were measured in lungs of the embryonic chick, and in tissue, lamellar bodies, and lavage fluid after hatching. Phosphatidylcholine (PC), the major phospholipid in surfactant, was fractionated and the amount and fatty acid composition of its disaturated (DSPC) component was determined. The synthetic rates of PC, DSPC, and other choline phospholipids were determined on days 14 and 19 of incubation from incorporation of 14C‐choline. Choline pool size was also estimated at these times. Phospholipid content of the lung increased most rapidly after day 18 of incubation with the greatest increase in PC. The PC synthesized just prior to breathing was enriched in DSPC, which constituted 45% of PC on day 19 and only 30% on day 14. DSPC content was even lower in embryonic liver and yolk. Incorporation of 14C‐choline in vitro into pulmonary PC, Sphingomyelin (Sphingo), and DSPC was greater in birds before breathing (day 19) than in the younger embryos. Choline pool size decreased between days 14 and 19 of incubation, but the synthetic rate of DSPC doubled in this interval. Increased accumulation and biosynthesis of pulmonary PC, Sphingo, and DSPC in lung tissue of the embryo paralleled appearance of lamellar bodies. In 5–6‐week‐old chickens the major pulmonary phospholipid was also DSPC. In lavage, 70% of PC was DSPC, predominantly dipalmitoyl PC. As in the mammalian lung, PC, especially its DSPC component, forms the major phospholipid of avian surfactant, and the synthesis of DSPC is specifically stimulated prior to breathing.
Prelethal symptoms of the killing action of some non‐kappa killers in the Paramecium aurelia complex
Authors: Jurand A. , Rudman B. M. , Preer J. R.
Published: June 2005

Changes occurring in sensitive paramecia following exposure to non‐kappa killer stocks bearing gamma, lambda, and sigma symbionts were investigated at the light and electron microscopic levels. The responses of sensitive cells to all these killer paramecia are the formation of large numbers of lysosomes, gradual degeneration of mitochondria, loss of ribosomes, production of autophagic vacuoles, and formation of blebs on the pellicle. In some cases the ultrastructure of macronuclei is affected and pellicular blebs are formed inside the cytopharynx. In addition, many of the investigated stocks cause the sensitive animals to lose the ability to discharge trichocysts when tested with a solution of saturated picric acid.
The importance of the presence of metabolizable sugars in a medium for in vitro fertilization of hamster eggs with postovulatory oviduct contents
Authors: Imai H. , Niwa K. , Iritani A.
Published: June 2005

Hamster eggs with postovulatory oviduct contents were added to a simple defined medium, without serum albumin, but supplemented with different combinations of energy sources. They were then inseminated by epididymal spermatozoa. In a medium containing D‐glucose but without pyruvate and/or lactate, high proportions of acrosome‐reacted spermatozoa (78–94%) and eggs undergoing fertilization (89–96%) were obtained 9–9.5h after insemination. With only pyruvate or lactate as substrates, or with both pyruvate and lactate, acrosome reactions occurred in only 2–4% of the sperm. When D‐glucose ranging in concentration from 2.78 to 8.34 mM was added, a high proportion (82–95%) of the eggs inseminated were found to be fertilized. Substituting D‐galactose, L‐glucose, L‐fucose, D‐lactose, or D‐saccharose for D‐glucose resulted in very low numbers of acrosome‐reacted sperm (0–12%) and fertilized eggs (0–7%). However, in the presence of metabolizable sugars, such as D‐mannose or D‐fructose, the acrosome reaction was seen in 78–85% of the sperm examined and 87–95% of the eggs tested were fertilized.
Survival and reproduction of the desert pupfish (Cyprinodon n. nevadensis) after acclimation to acid water
Authors: Gerking Shelby D. , Lee Raymond M.
Published: June 2005

The tolerance of desert pupfish, Cyprinodon n. nevadensis to acid water was tested by exposing a group of fish for 14 weeks to alkaline water resembling their natural habitat (pH 8.3) and another to sublethal acidity (pH 6.3). The difference in mean times to loss of equilibrium at pH 4.2 (sublethal = 19.2 ± 2.93 hours; control = 17.9 ± 5.37 hours) was not statistically significant, indicating a failure to acclimate to the sublethal acidity.

A reciprocal transfer experiment was performed with a sublethal (pH 6.3) and a control group (pH 8.3) to learn whether reproductive performance would compensate for acid stress. Reproductive performance was measured by egg production (eggs gm−1 day−1) and frequency of egg laying. In the first portion of the experiment the two groups were acclimated to their respective conditions for 3 weeks prior to a 3‐week measure of reproductive performance. The two groups were then reversed and tested again for 5 weeks. Reproductive performance of a control group was monitored for the 11‐week experimental period. No adaptation of the reproductive function occurred, since the transferred controls and acclimated sublethals were not statistically distinguishable. The sublethal group did not recover its reproductive capacity after transfer to the control level, suggesting either that permanent damage to some portion of the oogenesis process might have been suffered as a result of the acid exposure, or that the recovery was delayed beyond the 5‐week duration of this portion of the experiment.
The hare and the tortoise: Metabolic strategies in cardiac and skeletal muscles of the skink and the chameleon
Authors: Guppy M. , Davison W.
Published: June 2005

Two lizards ‐ a skink capable of fast short dashes, and a chameleon, incapable of fast movement ‐ have been studied to determine the degree of metabolic diversity that exists in this group of reptiles. Oxygen uptake measurements, skeletal muscle histochemistry, and enzyme and metabolite levels in cardiac and skeletal muscles reveal that the skink has a higher metabolic potential, both aerobic and anaerobic, than the chameleon. The difference, however, is not as large as is indicated by the behaviors of the two lizards. Levels of citrate synthase and B‐hydroxybutaryl CoA dehydrogenase in the hearts of both the lizards are high and indicate mammalian‐level metabolic capabilities.
Evidence that ectoderm influences the differentiation of muscle in the limb of the embryonic chick
Authors: Searls Robert L. , Smith Allen A.
Published: June 2005

Intact limb buds from stage 19 to 21 embryos differentiate to contain both cartilage and muscle in culture. If the limb ectoderm is removed, the limb mesoderm cells differentiate as cartilage and connective tissue but not as muscle. Intact limb buds from stage 19 embryos differentiate both cartilage and muscle when grafted to the chorioallantoic membrane, but differentiate only cartilage and connective tissue if the ectoderm is removed. The significance of limb ectoderm to muscle differentiation can be observed as late as stage 24. Both the prospective cartilage region and the prospective soft tissue region from the limb of a stage 24 embryo differentiate cartilage and muscle in the presence of limb ectoderm, but differentiate little, if any, muscle in the absence of limb ectoderm. The results indicate that the dorsal and ventral ectoderm have some influence on muscle differentiation.
Biochemical and immunohistochemical localization of alpha and beta keratin in avian scutate scales
Authors: O'Guin W. Michael , Knapp Loren W. , Sawyer Roger H.
Published: June 2005

We have determined the distribution of alpha and beta keratins in avian scutate scales using SDS‐PAGE and indirect immunofluorescence with non‐cross‐reacting rabbit antisera prepared to both alpha and beta keratins. Contrary to previous studies, we find that alpha keratin is definitely present in the epidermis of the outer scale surface as well as that of the inner surface and hinge region of the scale. In fact, all six alpha keratin polypeptides found in the whole scale epidermis are also present in epidermis taken exclusively from the outer scale surface. Three of these polypeptides demonstrate a specific enrichment in the epidermis of the outer scale surface when compared to the polypeptides of the entire scale epidermis. Immunofluorescence studies specifically localize the alpha keratins of the outer scale epidermis in the Stratum Basale and Stratum Intermedium, but the beta keratins are restricted to the Stratum Intermedium and Stratum Intermedium and Stratum Corneum.
Effect of polyamines on fertilization of mouse ova in vitro
Authors: Stanger J. D. , Quinn P.
Published: June 2005

After a 1‐hour preincubation of epididymal mouse spermatozoa at a concentration of 2 × 106/ml in 0.23 mM spermine, the proportion of F1 (C57BL × CBA) mouse ova fertilized after 1 and 2 hours was significantly greater than with untreated spermatozoa. Spermine also significantly increased the proportion of ova fertilized at the sub optimal sperm concentration of 2 × 105/ml. The stimulatory effect was lost when the protein source in the fertilization medium was changed from human serum albumin V (HSA) to HSA crystalline. This provides indirect evidence that albumin is directly involved in the capacitation process and that the crystalline is more potent than the fraction V preparation. At equimolar concentrations, spermidine was partially and putrescine was totally inhibitory to fertilization. Mechanisms whereby spermine may affect metabolic activity or sperm‐zona binding are discussed. It is suggested spermine may also be present in ovulatory fluid and therefore could potentially be involved in fertilization in vivo.
Transmission and scanning electron microscopic studies of the human sperm chromatin decondensed by micrococcal nuclease and salt
Authors: Sobhon Prasert , Chutatape Chutima , Chalermisarachai Panpaka , Vongpayabal Pandung , Tanphaichitr Nongnuj
Published: June 2005

The human sperm chromatin was gently decondensed by treating the sperm heads sequentially with micrococcal nuclease and 2 M NaCl. All histones, about 10% of DNA, and a small amount of degraded protamines were released into the soluble fraction, leaving mainly nucleoprotamines in the pellet fraction. Transmission and scanning electron microscopic studies revealed that the nucleoprotamine pellet consisted of chromatin cords of two dimensions, viz., 330‐ to 420‐Å and 650‐ to 1200‐Å thick cords laced together by very fine strands of 60‐ to 80‐Å fibers; both types of cords appeared knobby and had zig‐zag patterns throughout their length. It appeared that these cords were derived from two types of sperm heads of approximately equal population; one type contained chiefly the thick cords and the other chiefly the thin cords. Further treatment of the pelletnuclease‐NaCl with urea and mercaptoethanol resulted in the dissociation of the thick into the thin cords and unravelling of the thin cords into smaller sized fibers; whereas the treatment of the pelletnuclease‐NaCl with DNAase I resulted in the disappearance of the 60‐ to 80‐Å fibers, and the remaining cords were chiefly of thick type together with the sperm head exoskeletons. From these results the packing order of the chromatin in human sperm was proposed.
Isolation of an Arbacia sperm fertilization antigen
Authors: Eckberg William R. , Metz Charles B.
Published: June 2005

Antisperm antibody fragments (IFab) block sea urchin fertilization by inhibiting the acrosome reaction and consequently sperm‐egg attachment. We describe here a 68,000 dalton MW glycoprotein which neutralizes the fertilization‐inhibiting action of IFab. This glycoprotein is a minor component in SDS‐polyacrylamide gels of sperm membranes, but is greatly enriched in lithium diio‐dosalicylate extracts of the membranes. Final purification of the antigen was accomplished by elution from preparative SDS‐polyacrylamide gels. This glycoprotein is evidently the sea urchin sperm receptor which interacts with the egg jelly coat and acts as a “trigger” for the acrosome reaction.
Studies of phospholipase A2 related to the hamster sperm acrosome reaction
Authors: Llanos Miguel N. , Lui Chung W. , Meizel Stanley
Published: June 2005

This report describes studies of innate and exogenous phospholipase A2 related to the acrosome reaction of golden hamster cauda epididymal sperm in vitro. Two acrosome reaction‐inducing systems were used: a nonsyn‐chronous system with epinephrine, and a synchronous system with the protonionophore FCCP. After a high percentage of sperm had undergone AR (in both systems) an increased phosphatidylcholine hydrolyzing activity was found in incubation media supernatants after partial purification by Affi‐Gel Blue chromatography. A preliminary characterization demonstrates that the activity was stimulated by Ca2+, detectable at pH 7.4‐‐7.8, but not at pH 4.5, and inhibited by p‐bromophenacyl bromide and mepacrine. Thus, it appears that a phospholipase A2 was released as a result of the acrosome reaction. BSA purified by TCA precipitation and ethanol resolubilization (TCA‐BSA), utilized in both types of incubations did not contain associated phospholipase A2 activity, but did contain an associated phosphatidylcholine hydrolyzing activity. The nonphospholipase A2 activity was removed by further purification of the TCA‐BSA by Affi‐Gel Blue chromatography, but the resulting highly purified TCA‐BSA was still able to induce capacitation and acrosome reactions in hamster sperm at the same level as prior to column chromatography. Incubations of the sperm in the presence of a partially purified bee venom phospholipase A2 did not stimulate hamster sperm AR over control values in the presence of epinephrine, but did so in the absence of epinephrine (probably by mimicking the action of the innate sperm head phospholipase A2). These results provide further support to earlier studies from this laboratory suggesting the involvement of a sperm head phospholipase A2 as an important factor in the mammalian sperm acrosome reaction.
Avian feather morphogenesis: Fibronectin‐containing anchor filaments
Authors: Haake Anne Reeves , Sawyer Roger H.
Published: June 2005

During feather morphogenesis anchor filaments, continuous with the basement membrane, extend deep into the dermis. We find that these anchor filaments give intense fluorescence with antifibronectin (FN) antibody, using indirect immunofluorescence and immunoelectron microscopic techniques. These filaments are abundant in the dermis of the developing feather germ, yet are not present in the dermis beneath the epidermis of the elevated feather primordia. We suggest that these FN‐containing anchor filaments function in establishing the epidermal placodes of feathers and/or the organization of the feather dermis.
Analysis of the Drosophila female sterile mutant, tiny, by means of pole cell transplantation
Authors: Dimario Patrick J. , Hennen Sally
Published: June 2005

Oogenesis in Drosophila females homozygous for the female sterile mutation, ty, is characterized by morphological abnormalities in both the somatically derived follicle cells and the germ line derived nurse cells and oocyte. In order to identify the target cells of the mutation, reciprocal pole cell transfers were carried out between ty and ty+ embryos. The resulting mosaic ovaries contained host and donor germ line cells derived from the pole cells but only host follicle cells. Our results show that ty is a germ line mutation. The ty follicle cells in cooperation with normal nurse cells and oocyte lead to the production of normal flies. Consequently, the follicle cell abnormalities in ty egg chambers result from the expression of the mutation in the nurse cells, oocyte, or both.
Effect of gonadotropins and prostaglandin on cumulus mucification in cultures of intact follicles
Authors: Phillips David M. , Dekel Nava
Published: June 2005

Follicles of 28 day‐old prgnant mare serum gonadotropin (PMSG)‐primed rats, were cultured for up to 24 hours in the presence or absence of ovine gonadotropins, highly purified rat gonadotropins, dibutyryl cyclic AMP (dbcAMP), methylisobutylxanthine (MIX), choleratoxin (CT), or prostaglandin E2 (PGE2). The morphology of the cumulus‐oocyte complexes isolated from these follicles was subsequently examined with the light microscope. Cumulus mucification was studied under the different culture conditions using scanning electron microscopy (SEM) and the hyaluronidase sensitivity test. The features of the cumulus‐oocyte complexes in the control cultures did not change throughout the incubation period, while complexes from follicles incubated with LH, FSH, dbcAMP, MIX, CT, or PGE2 changed their appearance and accumulated extracellular mucoid material. Treatment of these cumuli with hyaluronidase resulted in lysis of the extracellular mucus and dispersal of the cumulus masses. The results of this study agree with our earlier observation that the maturation of the cumulus‐oophorus, which occurs in vivo following the LH surge, can be induced in vitro by either gonadotropins or cAMP. Prostaglandin E2 did not affect cumulus cells, unless incubated enclosed by their follicles. This suggests that this hormone may influence the cumulus cells indirectly, probably via other components.
Effect of hyaluronidase treatment on the distribution of cranial neural crest cells in the chick embryo
Authors: Anderson Cheryl B. , Meier Stephen
Published: June 2005

The cranial paraxial mesoblast is patterned into segmental units termed somitomeres. Recently we demonstrated the morphological relationship between the migratory pathways of cranial neural crest cells and the patterned primary mesenchyme of chick embryos (Anderson and Meier, '81). Since extracellular matrix, particularly hyaluronate, is also distributed in cranial crest pathways, embryos were given sub‐blastodisc injections of hyaluronidase just prior to neural tube fusion and neural crest migration to remove matrix. Histological sections of enzyme‐treated embryos showed that Alcian blue staining of hyaluronate was significantly reduced. Surface ectoderm appeared collapsed on the subjacent mesoderm as well. Examination of embryos with the scanning electron microscope (SEM) revealed that paraxial mesoderm remained segmentally patterned even though it appeared more condensed because of a reduction in intercellular space between mesenchymal cells. In enzyme‐treated embryos, the rostral crest cells spread over the dorsal surfaces of the first four somitomeres, as they would do normally. This distribution of neural crest cells occurs even when enzyme treatment interferes with neural tube fusion at that level. We conclude that 1) neural tube fusion is not a prerequisite for the timely release of cranial crest in the chick embryo and 2) that much of the organized hyaluronate‐rich matrix that lies in the path of cranial crest is not essential for crest emigration or patterned distribution.
Sperm penetration into rat ova fertilized in vivo
Authors: Phillips David M. , Shalgi Ruth
Published: June 2005

The mechanics of sperm entry into the oocyte were examined in rat ova fertilized in vivo. With the scanning electron microscope we observe that the spermatozoon is first associated with the oocyte by the region of the convex surface of the sperm head which is immediately anterior to the postacrosomal region. At this early stage the anterior tip of the sperm head is directed away from the oocyte surface. The spermatozoon subsequently appears to rotate so that it comes to lie on its “side.” The membrane over the sperm head becomes free of microvilli and a large incorporation cone is subsequently formed. It is concluded that in the rat initial fusion of sperm and egg probably occurs between the oolemma and the sperm plasmalemma over the equatorial segment of the acrosome at the convex surface of the sperm head which is just anterior to the postacrosomal region.
Regulation of melatonin in the retinae of guinea pigs: Effect of environmental lighting
Authors: Pang S. F. , Yu H. S. , Tang P. L.
Published: June 2005

We studied the effect of environmental lighting on the level of melatonin in the retinae of guinea pigs. Male pigmented guinea pigs were adapted to 12‐hour light: 12‐hour dark (with lights on at 0600 hours) for 2 weeks. In experiment 1, two groups of animals were decapitated at 1600 and 0400 hours. Melatonin was extracted from retinae and quantified by radioimmunoassay. A diurnal rhythm of retinal melatonin level per pair of retinae was demonstrated. In experiment 2, one group was subjected to an extended dark period (lights remained off after 0600 hours) while the control group remained on the normal photoperiod on the day of sacrifice. Both groups were killed at 1200 hours. The retinal melatonin level in the group under extended dark period was significantly higher (P < 0.05) than that of the control. In experiment 3, one group was exposed to an extended light period (lights remained on after 1800 hours) and the control group remained on the normal lighting schedule. Both groups were killed at 2400 hours. The retinal melatonin level in the group exposed to an extended light period was significantly lower (P < 0.05) than that of the control. Thus, darkness induces an increase while light causes a decrease in retinal melatonin level.
The “ventral organ” of Jasus paulensis (Crustacea, Decapoda)
Authors: Vranckx R. , Durliat M.
Published: June 2005

A “ventral organ” mainly made up of lipoprotein cells is observed in Jasus paulensis and all the Decapoda we have been studying. It is extensive during the early premolt stages because of the development of both number and size of cells. Sometimes, the presence of smaller finely granular cells is noted, chiefly in early premolt stages. Crystals are visible from stage D1′ to stage D2 in extracellular spaces between the “adipocyte type cells.” They are postulated to be calcium deposits. The “organ” contains many lipids; most of them are phospholipids (phosphatidyl‐choline, phosphatidyl‐ethanolamine) but a few are neutral fats. This “organ” seems to be only a preferential site for the accumulation of adipose tissues. The functions of this ventral tissue as well as those of the cyclic adipose tissue are discussed in relation to the storage of materials, synthesis of lipoproteins, and general metabolism in Crustacea.
Wavelike propagation of stretching and shrinkage in the surface of the newt's egg before the first cleavage
Authors: Sawai Tsuyoshi
Published: June 2005

Small carbon particles were attached to the surface of uncleaved fertilized eggs of the newt, Cynops pyrrhogaster, to analyze movement of the egg surface. Distances between pairs of particles were measured on still pictures photographed at intervals of 5 minutes. Measurements were made parallel to the cleavage furrow and perpendicular to it. The surface of the animal pole region began stretching about 40 minutes before the first cleavage, and then shrank about 20 minutes later. The phases of surface‐stretching and ‐shrinkage propagated from the animal pole toward the equatorial region. The shrinking region was observed in the photographs as a narrow circular zone of more concentrated pigment which was probably the second surface contraction wave found by Hara ('71).
Structural cell number and regeneration in Chlorohydra viridissima
Authors: Shostak Stanley
Published: June 2005

Representative Chlorohydra viridissima were cut so that head‐end pieces had different structural cell numbers and tentacle numbers. Structural cell number was calculated from cell counts on macerated preparations. The number of tentacles regenerating on these pieces changed significantly as a function of the structural cell number, but not the tentacle number on the original pieces. The interaction term for the original tentacle number and structural cell number on tentacle regeneration was also significant. Foot regeneration on the head‐end pieces was a function of the length of pieces and mutually exclusive with the formation of tentaclelike basal spikes and the repolarization of pieces whereby an original tentacle became a basal structure. The number of tentacles regenerating on the basal stump peaked at one‐quarter the length of the gastric region in violation of expectations based on gradient models of morphogenesis. Structural cell number appears to be a major morphogenic determinant in regenerating Hydra.
The peripheral generation of action potentials in excitatory motor neurons of a crab
Authors: Lazarus Robert E. , Stephens Philip J. , Mindrebo Norman
Published: June 2005

The effects of temperature on the firing patterns of the excitatory motor supply to the bender muscle were examined in autotomized walking limbs of the crab Pachygrapsus crassipes. A brief electrical shock applied to the limb nerve evoked an action potential in one or both of the excitor axons and an excitatory junctional potential (ejp) in the bender muscle fibers. However, at high temperatures a single shock to one of the excitor axons (E2) resulted in a short train of nerve spikes and a concomitant burst of ejps. Extracellular recordings made from two sites along the E2 axon demonstrated that the additional action potentials are generated peripherally. Furthermore, myogram recordings from bender muscles in untethered animals indicate that peripheral generation of spikes does take place in intact crabs exposed to high temperatures.

The peripheral generation of action potentials exhibited a critical temperature threshold which could be altered by acclimation and by low levels of ethanol in the saline bathing the autotomized limb preparation. This phenomenon may, therefore, be closely associated with membrane fluidity.
Sperm interaction with the zona‐free hamster egg
Authors: Binor Zvi , Sokoloski Joseph E. , Wolf Don P.
Published: June 2005

The interaction of sperm with the zona‐free hamster egg was studied. Hamster sperm were capacitated in Tyrodes media, containing 50% heat‐inactivated serum and used to inseminate zona‐free eggs in BWW containing 10% serum. Capacitated sperm began fusing with eggs within the first hour of insemination and by 3 h penetration had ceased as indicated by the absence of further changes in the mean number of sperm incorporated per egg. Penetration by capacitated hamster sperm was linearly related to the log of the motile sperm concentration at concentrations above 104 cells/ml. The viability of sperm and eggs in culture was limited in these studies to approximately 3–5 h. The existence of a block to unlimited sperm penetration of the zona‐free egg was sought in reinsemination experiments. A relatively low sperm concentration was used to initiate egg responses, followed, at timed intervals, by reinsemination with a high challenge concentration of sperm. Subsequent polyspermy levels reflected the presence or absence of the egg's block to polyspermy response. In order to circumvent the problems arising from the rapid aging of hamster sperm in culture, mouse sperm were employed, a convenience afforded by the lack of species specificity in this egg. Reinseminated eggs incorporated additional sperm during the challenge; therefore, the hamster egg is not capable of preventing unlimited sperm penetration. The implications of these findings to the use of the zona‐free hamster egg test in fertility evaluation is discussed.
Effects of rearing temperature on cuticle permeability and epicuticular lipid composition in Drosophila pseudoobscura
Authors: Toolson Eric C.
Published: June 2005

The effects of larval and pupal thermal regime on adult transcuticular water loss rates and epicuticular hydrocarbon composition in Drosophila pseudoobscura were determined. Temperatures encountered by the larval stage had no effect, but flies emerging from pupae maintained at 24°C exhibited significantly lower cuticular permeabilities than those emerging from pupae maintained at 17°C. More than 50% of the variance in cuticular permeability was accounted for by variation in the proportion of n‐pentacosadiene in the epicuticular hydrocarbons. High transcuticular water loss rates were correlated with higher proportions of relatively short‐chain, methyl‐branched alkanes and alkadienes. High proportions of longer chain lengths of both branched alkanes and alkadienes were associated with lower cuticular permeabilities. The molecular basis for these findings is discussed.
The dynamics of body water in the booklouse Liposcelis bostrychophilus (Badonnel)
Authors: Devine T. L.
Published: June 2005

Liposcelis bostrychophilus, whether in culture or fasting, was found to maintain the amount of its body water at nearly 66% of its fresh weight while in air of at least 60% relative humidity between temperatures of 7°C and 42°C. In these conditions intervals of body water loss reaching 1 to 2 μg alternated with recovery of the loss by the physiological absorption of water from vapor at a rate many times that of the water loss. In other conditions a loss of one‐half of the body water could be survived. The time dependence of a change in the mass or the tritium content of body water was that of a single compartment from which water molecules were cleared by first‐order processes, primarily diffusion, having rates in proportion to the momentary mass of body water while water entered from vapor, was metabolically produced, and some evidently was cleared by processes having rates independent of the body water mass. The physiological absorption process was seen to reach its full rate or to stop within minutes, and it was accompanied by a reduced rate of body water clearance. In any particular physical surroundings the body water mass approached a steady‐state value with the half‐time of the first‐order clearance processes. A few measurements of these quantities, over the ranges of temperature and relative humidity, afforded accurate prediction of the recovery time or the longevity in other conditions.
Carbamoyl‐phosphate synthase (ammonia) of rat and axolotl liver: Determination of immunological cross‐reactivity without purification of the axolotl enzyme
Authors: Lamers Wouter H. , De Graaf Andre , Mooren Piet G. , Moorman Antoon F. M. , Charles Rob
Published: June 2005

A method has been developed to establish the degree of cross‐reactivity of an antiserum raised against purified carbamoyl‐phosphate synthase (ammonia) from adult rat liver, toward a homologous enzyme from another species without purification of the latter enzyme. For that purpose the ratio between enzyme activity and enzyme protein, i.e., the molecular specific activity in crude liver extracts, was determined by two independent methods.

When the molecular specific activity was determined by means of radioimmunoassay using a specific antiserum raised against rat liver carbamoyl‐phosphate synthase this ratio was a factor four higher for the axolotl than for the rat.

Both axolotl and rat liver carbamoyl‐phosphate synthase appear as a very prominent band with an apparant molecular weight of 165,000 after sodium dodecyl sulphate‐polyacrylamide gelelectrophoresis. Therefore, the amount of enzyme protein could be determined by means of densitometry of this band using purified rat liver carbamoyl‐phosphate synthase as a standard. The ratio between enzyme activity and enzyme protein calculated from this method appeared to be the same for axolotl and rat.

From these results it can be deduced that the degree of cross‐reactivity between rat and axolotl liver carbamoyl‐phosphate synthase is approximately 25% when using the antiserum raised against the rat liver antigen.
Regulation of crustacean morphogenesis in larvae of the mud crab Rhithropanopeus harrisii
Authors: McConaugha John R.
Published: June 2005

Starvation of penultimate stage brachyuran larvae within 15 hours after ecdysis results in the suspension of the molt cycle in the early premolt stages. This suspension can be maintained for up to 7 days. Using this as a tool to extend the duration of the penultimate zoeal stage, it was possible to demonstrate that crustacean morphogenesis is at least partially regulated by a time‐dependent process which is independent of the number of larval instars.
Gonadal differentiation in frogs, Rana japonica and R. brevipoda, raised from UV irradiated eggs
Authors: Shirane Terukiyo
Published: June 2005

The gonadal differentiation of anurans, Rana japonica and R. brevipoda, was examined in animals raised from eggs which had been irradiated at the vegetal hemisphere with UV (9300 erg/mm2) at the 2‐cell stage. In R. japonica about 70% of the larvae at stage I from the pressed and UV‐irradiated eggs were germ cell free, but at a stage immediately after metamorphosis all animals had at least some germ cells, although their gonads often were extremely small and poorly differentiated. When male animals matured sexually, many of them had abnormal gonads. However, all of them were shown by artificial means to be capable of fertilization. In the nonpressed and irradiated group, no larvae were germ cell free and the animals immediately after metamorphosis showed nearly normal gonadal differentiation except for the presence of a few degenerate oocytes in the ovaries. The results in R. brevipoda were basically similar to those in R. japonica. In both species, sex ratios were determined at two stages, the first immediately after metamorphosis and the other when the animals matured, as based on gonad morphology and histology and on external sexually dimorphic characters as well. Sex ratios at these two stages in frogs from the pressed and irradiated eggs differed markedly in R. brevipoda. The ratio was normal at metamorphosis but high M/F ratios occurred when animals became mature. That sex reversal took place in this species as well as in R. japonica (in which sex‐ratio deviation was not statistically significant) was supported by the sex ratios of the progenies of these supernumerary males.
Gynogenesis caused by ultraviolet irradiation of salmonid sperm
Authors: Chourrout D.
Published: June 2005

Gynogenetic rainbow trout lines can be produced easily with the simple UV sperm irradiation technique detailed in this study. The dose effect on embryonic survival rate is called a pseudo “Hertwig effect” because of major differences with results of gamma irradiation: Some mixing of various karyotypes (from diploid to haploid number) were obtained with mean doses, probably because of the weak penetrating power of the ultraviolet rays. Irradiations lasting 4 minutes or more are required to produce homogeneous haploid progeny; heat shock applied to such fertilized eggs results in diploid fry of the maternal phenotype.
Cultivation of mouse embryos explanted at 11 days
Authors: De Villarreal L. Martínez , Fisher D. L.
Published: June 2005

A method for cultivation of 11‐day mouse embryos (plug day = day 0) is presented. Competence of the visceral yolk sac and serum dilutions were tested. Eleven day mouse embryos were cultivated for 24 hours with the visceral yolk sac either opened or left intact. Fetal calf serum (FCS) at 0%, 25%, and 50% dilutions balanced with Waymouth's medium was used as cultivation medium. Viability and growth of the embryos were evaluated by heart rate at 6 hours, and protein accumulation and differentiation at 24 hours. At 6 hours, best results were found in those embryos with the visceral yolk sac intact. Serum dilutions at this time were not important for viability. At 24 hours, only those embryos cultivated with the visceral yolk sac opened were alive. Significant increase in viability was obtained when a 50% dilution of FCS was used. There was a significant increase in protein accumulation for viable embryos at 24 hours.
Lactate dehydrogenase of Xenopus laevis laevis and Xenopus borealis depends on a multiple gene system
Authors: Wolff J. , Kobel H. R.
Published: June 2005

Lactate dehydrogenase isozymes have been reinvestigated in Xenopus laevis laevis and Xenopus borealis. High resolution zymograms of various organs demonstrate that in both species the LDH isozymes are governed basically by a three‐gene system: Ldh‐a coding for positively charged polypeptide, and Ldh‐b and Ldh‐c for negatively charged polypeptides (at pH 8.9). These three LDH subunits when assembled in tetramers show differnetial sensitivity to heat intactivation; the C4 homotetramer in the most liable isozyme. Xenopus is thus similar to Ostechthyes, birds, and mammals that also have a three‐gene system for LDH. With respect to tissue specific isozyme expression, Xenopus resembles the more primitive families of bony fish.

Superimposed on this three‐genesystem is a probable gene duplication for both LDH‐a AND LDH‐b. Heterotetrameric isozymes are formed between the various subunits leading to multibanded zymograms with a total of at least 21 distinct zones of LDH activity. The expression of genes is tissue specific not only for the basic genes, but also for their presumed duplicates. Since both species of Xenopus are ancient teetraploids, duplication of Ldh genes is not surprising.