bluuebunny/crossref_metadata_2025_split huggingface dataset:
Makisterone A: The molting hormone of larval Oncopeltus?
Authors: Kelly Thomas J. , Woods Charles W. , Redfern Robert E. , Bořkovec Alexej B. 
Published: June 2005

AbstractThe major ecdysteroids of last‐stage Oncopeltus fasciatus larvae were determined by HPLC/RIA analysis. An ecdysteroid other than ecdysone or 20‐hydroxyecdysone, probably makisterone A, was the major ecdysteroid in hemolymph and in whole body extracts of 4‐ to 5‐day‐old larvae, when hemolymph ecdysteroid titers were at their peak. Little, if any, ecdysone or 20‐hydroxyecdysone was detected in the hemolymph. Bioassay of the relative activities of ecdysone, 20‐hydroxyecdysone, and makisterone A in last‐stage larvae revealed that makisterone A was ten times more active than 20‐hydroxyecdysone, and that ecdysone was inactive at doses as high as 1 mg/ml, its limit of solubility in 10% ethanol. Thus, it is suggested that makisterone A is the molting hormone in Oncopeltus. The implications of this discovery are discussed.
Cuticle synthesis and inhibition of vitellogenesis: Makisterone A is more active than 20‐hydroxyecdysone in female milkweed bugs
Authors: Aldrich J. R. , Svoboda J. A. , Thompson M. J. 
Published: June 2005

AbstractMakisterone A (24‐methyl‐20‐hydroxyecdysone) is approximately ten times more potent than 20‐hydroxyecdysone in the stimulation of cuticle synthesis and inhibition of vitellogenesis when injected into 3‐day‐old virgin females of Oncopeltus fasciatus. By day 6 postinjection with an active dose of makisterone A, the new cuticle appears identical in color pattern and morphology to the old adult cuticle, although the insects never undergo ecdysial contractions. Since milkweed bugs are also known to be incapable of dealkylating phytosterols, and makisterone A has been previously identified as the predominant ecdysteroid from embryonated eggs of this species, it is likely that makisterone A is the molting hormone of O. fasciatus or is closer to the structure of the indigenous hormone than is 20‐hydroxyecdysone.
Differentiation of the avian latissimus dorsi primordium: Analysis of fiber type expression using the myosin ATPase histochemical reaction
Authors: Butler Jane , Cosmos Ethel 
Published: June 2005

AbstractTypically, fast twitch fibers of the adult avian posterior latissimus dorsi (PLD) muscle express alkali stable myosin ATPase histochemical activity, whereas slow tonic fibers of the anterior latissimus dorsi (ALD) muscle exhibit dual acid and alkali stability. Since PLD fibers cross‐reinnervated by the nerve of the ALD muscle also demonstrate dual stability, we sought to determine whether the ALD nerve induces this new phenotype de novo or de‐represses an embryonic phenotype repressed during further development in ovo. Chick embryos from Day 2 in ovo onward were frozen in toto, and the development of myosin ATPase histochemical profiles following alkali and acid preincubation was determined for myo‐genic cells destined to form the ALD and PLD muscles. In addition, the silver cholinesterase reaction was employed on serial sections to investigate early muscle‐nerve interaction in ovo. Our results indicate that all myogenic cells of the primary dorsal muscle mass, including those of the future ALD and PLD muscles, demonstrate their first myosin ATPase response at Stage (St) 25. At this time (4.5 days in ovo), only alkali stable enzymic activity is expressed. By St 28 (5.5 days) a distinct latissimus dorsi (LD) primordium has cleaved from the dorsal muscle mass and the entire primordium still exhibits only alkali stability. As development proceeds and the LD primordium separates into recognizable anterior and posterior regions (St 29, 6.0 days through St 30, 6.5 days), the future PLD muscle continues to express only alkali stability, whereas the future ALD muscle now demonstrates dual stability. By St 32 (7.5 days), these two muscles are completely separated, and during the remainder of in ovo development the profiles characteristic of adult slow tonic versus fast twitch fibers remain unaltered. Thus, our results indicate that, during cross‐reinnervation ex ovo, the ALD nerve induces the expression of a new phenotype never exhibited by potential fast twitch PLD fibers during the entire embryonic period, including their incipient formation. Moreover, our results indicate that the histochemical reaction for myosin ATPase activity provides an excellent enzymic marker both for the identification of myogenic cells and individual muscle primordia, and, for the detection of muscle fiber type differentiation during the first week of development in ovo.
Regional changes in the binding of [3H] concanavalin A to mouse blastocysts at implantation: An autoradiographic study
Authors: Carollo J. R. , Weitlauf H. M. 
Published: June 2005

AbstractImplanting and delayed‐implanting mouse blastocysts were incubated in vitro with [3H] concanavalin A (Con A), and the distribution of binding on their surfaces was determined by light microscopic autoradiography. The density of binding was uniform on the trophectoderm of delayed‐implanting embryos and was not changed on the polar surface of implanting embryos. However, binding was reduced on the proximal mural and distal mural trophectoderm of implanting blastocysts by 36% and 60%, respectively. These results suggest that there is a regional reduction in the density of mannose‐like sugars on the surface of mouse blastocysts at the time of attachment and implantation.
Resumption of DNA synthesis during activation of delayed implanting mouse blastocysts
Authors: Given Randall L. , Weitlauf Harry M. 
Published: June 2005

AbstractCell division ceases in mouse blastocysts during the extended dormant period associated with delayed implantation but resumes following activation of the embryos by administration of 17β‐estradiol to the mother. To determine the temporal and spatial aspects of the resumption of DNA synthesis during activation, blastocysts were recovered from delayed implanting females at various intervals after an injection of 17β‐estradiol, incubated with 3H‐thymidine in vitro, and prepared for light microscopic autoradiography.Although less than 4% of the cells were labeled in delayed implanting embryos, the proportion of labeled cells increased soon after the administration of 17β‐estradiol and reached a maximum of over 50% by 24 hours. This increase in labeling was not uniform in all regions of the embryo, i.e., the labeling index of the inner cell mass began a steady increase immediately after the injection of 17β‐estradiol while labeling of the polar and proximal mural trophoblast remained depressed for 6 and 12 hours, respectively, and only then began to increase. No labeling was present over the distal mural trophoblast in delayed implanting or activated blastocysts although cytological changes characteristic of primary giant cell transformation were present in activated embryos. These results indicate that the resumption of DNA synthesis is part of the overall increase in metabolic activity associated with activation. Furthermore, the sequential pattern of resumption of synthesis suggests that the ICM may influence the initiation of DNA synthesis in the surrounding trophoblast.
Scanning electron microscopic observations on sperm penetration in teleostean fish
Authors: Iwamatsu T. , Ohta T. 
Published: June 2005

AbstractThe process by which a spermatozoon penetrates through the micropyle apparatus into the egg cytoplasm in the teleost, Oryzias latipes, was examined with scanning electron microscopy. In the unfertilized egg, the egg surface beneath the inner opening of the micropylar canal did not differ distinctly from the rest of the animal pole area. A spermatozoon attached effectively to the egg 1–3 seconds after insemination. In the initial step of penetration, the spermatozoon still within the micropylar canal attached perpendicularly at its apical tip to the egg surface, then the sperm head was rapidly engulfed by the folded egg surface with its many microvilli. A large blister‐like fertilization cone with a microvillus‐free surface appeared on the egg surface surrounding the penetrating spermatozoon. Concomitantly, breakdown of the cortical alveoli was initiated in the animal pole. The spermatozoon disappeared from the outer surface of the egg before the fertilization cone completely retracted.On the basis of these observations with Oryzias eggs, two steps in the sperm penetration process could be recognized: The first step was a rapid engulfment by the folded egg surface and the second was a slow engulfment by fertilization cone synchronized approximately with the initiation of the cortical reaction. The mechanism of block to polyspermy in teleostean eggs was discussed.
Comparison of hemoglobins from the genus Xenopus (amphibia salienta)
Authors: Muir A. V. 
Published: June 2005

AbstractA survey of the electrophoretic mobility of hemoglobins of 14 species and subspecies of the genus Xenopus was undertaken. It was found that the variation between the different taxons considered was quite important in the number and the degree of the hemoglobin bands on polyacrylamide slab gels. The profiles of the hemoglobin electrophoretic pattern in tube gels gave corresponding results, confirming the variation between the different Xenopus species. The degree of resolution obtained on polyacrylamide slab gels was insufficient to allow one to distinguish between the subspecies of Xenopus laevis. Specific staining of the gels showed that the protein bands were in fact hemoglobins.From the results obtained it appears that there are relative differences in the number and mobility of hemoglobin bands between the different species, these differences being important enough to stimulate interest in further investigation in this field, but, as far as this preliminary investigation indicates, not clear‐cut enough to use as a method of identification for isolated unknown species.
Development of the adult pelage in normal and hormone‐injected spiny mice (Acomys cahirinus)
Authors: Martin‐Dennis G. , Peitz B. 
Published: June 2005

AbstractThe dorsal pelage of the adult Egyptian spiny mouse (Acomys cahirinus) consists primarily of coarse brittle spines which differ from those of the juvenile pelage. The development of the adult pelage in juvenile spiny mice was examined in normal and estradiol‐or testosterone‐injected animals. Females complete the development of their adult pelage significantly faster than males. Both estradiol and testosterone injections speed pelage development in males. Testosterone causes a significant delay in the completion of the female's pelage. Studies of replacement of adult spines show that spine replacement is mosaic and slower than in other murid rodents.
The effect of pinealectomy, continuous light, and continuous darkness on metamorphosis of anadromous sea lampreys, Petromyzon marinus L.
Authors: Cole W. C. , Youson J. H. 
Published: June 2005

AbstractThe role of the pineal complex in lamprey metamorphosis was investigated by examining the influence of pinealectomy and continuous light and darkness on the initiation of this event in anadromous sea lampreys, Petromyzon marinus L. Larval lampreys, which on the basis of a condition factor were considered likely to enter metamorphosis in July, were separated in May of 1979 and 1980 into the following groups: (1) intact controls, (2) sham‐operated controls, (3) pinealectomized individuals, (4) those exposed to continuous light, and (5) those exposed to continuous dark. A statistical analysis of the numbers of animals that entered metamorphosis in each group indicated that the pineal complex is essential for the initiation of metamorphosis but that this process is not influenced by continuous light or dark. The importance of the pineal complex to metamorphosis was supported by morphological evidence that, in all presumably pinealectomized individuals that entered metamorphosis, the complex had apparently not been removed during the surgical procedure. The ways in which the pineal complex may be involved in lamprey metamorphosis are discussed.
Sexual dimorphism of SDS peptide patterns from the submaxillary glands of mice
Authors: Kim Yong Kyu , Ogita Zen‐Ichi 
Published: June 2005

AbstractIn mice (Mus musculus) sexual dimorphism is evident in the structure and function of the submaxillary glands, convoluted tubules being much more prominent in males than in females. Several enzymes are more abundant in the male gland. We have examined the submaxillary glands of male and female mice for the amounts of arginine peptidase and have made electrophoretic scans of SDS peptides in extracts of male and female glands during postnatal development and after androgen treatment. Larger peptides are relatively more abundant in female extracts, and smaller peptides are more abundant in the male extracts. The peptide patterns reflect the amount of arginine peptidase present in the extracts. No arginine peptidase could be detected in submaxillary salivary glands of mice from birth until 3 weeks of age. Then enzyme activity gradually increased, apparently induced by androgen hormones. The amounts of SDS peptides of high molecular weight steadily decreased with increasing age of the mouse and with increasing titers of arginine peptidase. Castration of the male led to the appearance of female SDS patterns; male patterns reappeared after treatment with testosterone. Females could be induced to form male patterns of SDS peptides by treatment with androgen hormones.
The level of N‐acetylserotonin and melatonin in the brain of male rats: Diurnal variations and effects of pinealectomy
Authors: Pang S. F. , Tang P. L. , Yu H. S. , Yip M. K. 
Published: June 2005

AbstractThe levels of N‐acetylserotonin and melatonin (n‐acetyl‐5‐methoxytryptamine) in the rat brain were studied. Male rats were housed under a photoperiod of 12L:12D. After 2 weeks, the rats were sacrificed in light or in dark at 4‐hour intervals round the clock. Brain melatonin and N‐acetylserotonin were extracted by chloroform at ⩾ pH 10 and ethyl acetate at ⩽ pH 3 respectively and quantified by radioimmunoassay. There was a circadian rhythm of brain melatonin (F < 0.05) with a nadir at 1600 h and a zenith at 0400 h. Brain N‐acetyl‐serotonin, unlike brain melatonin, demonstrated no diurnal variation. Effects of pinealectomy on brain N‐acetylserotonin and melatonin were also studied. Male rats were housed as noted. After 2 weeks, they were pinealectomized or shamoperated. The animals were killed in light or in dark 1 week after operation. The levels of brain melatonin at 2400 h and 0400 h were significantly lowered (P < 0.5) following pineal removal. Pinealectomy, however, has no observable effect on the level of brain N‐acetylserotonin. Our findings suggest that (1) there is a diurnal rhythm of brain melatonin, (2) the elevation of brain melatonin in the dark period is dependent on the pineal, (3) brain N‐acetylserotonin has no diurnal variation, and (4) brain N‐acetylserotonin is not affected by pinealectomy.
Effects of excising the apical ectodermal ridge on the development of the marginal vasculature of the wing bud in the chick embryo
Authors: Feinberg Feinberg Richard N. , Saunders John W. 
Published: June 2005

AbstractThe limb bud of the chick embryo depends for its outgrowth on an interaction between the apical ectodermal ridge (AER), which rims the apex of the bud, and the subjacent limb bud mesoderm. This report describes the results of experiments that were designed to test whether a relationship exists between the AER and the origin of the distinctive marginal veins, which drain the early arterial supply and capillary bed of the wing bud. All of the AER or localized portions of it were excised from wing buds of embryos at stages 17–23. Effects of the operation on the vascular pattern were analyzed in specimens whose blood vessels were injected with India ink at appropriate postoperative intervals. Excision of all or part of the AER at stages prior to the formation of the marginal vein results in complete or partial failure of the marginal veins to form, depending on the extent of ridge deletion. Once the marginal vein is formed proximally, however, it persists proximally even after the AER is removed, but distally it fails to form. Limb bud mesoderm, encased in backskin ectoderm and grafted to a host embryo, fails to form a marginal vein, indicating that nonridge ectoderm will not substitute for the AER in promoting normal vascularization. Isolated limb buds grafted to the chorioallantoic membrane with their normal ectodermal covering show normal vasculogenesis, indicating that the vascular pattern of the limb is intrinsically determined. These results indicate that the AER is required for the establishment of the marginal veins and the formation of a characteristic vascular pattern in the limb.
Ammonia excretion by the gills of two marine teleost fish: The importance of NH4+ permeance
Authors: Goldstein Leon , Claiborne James B. , Evans David E. 
Published: June 2005

AbstractVarying the concentration of un‐ionized ammonia (NH3) in the medium perfusing the gills of the isolated fish head while holding the total ammonia (NH4+ + NH3) concentration constant had no significant effect on gill ammonia excretion. In contrast, alteration in the medium NH4+ concentration at a fixed NH3 concentration produced a significant change in ammonia excretion. Thus, gill ammonia excretion was related to medium NH4+, not NH3, concentration.
Ecdysteroid induction of cell surface contacts in a Drosophila cell line
Authors: Yudin Ashley I. , Clark Wallis H. , Chang Ernest S. 
Published: June 2005

AbstractDrosophila Kc cells are usually spherical in shape and are relatively free of cell‐cell contacts. Soon after exposure to 20‐hydroxyecdysone they develop extensions, assume a fibroblastic shape, and closely adhere to adjacent cells by means of cell‐cell contacts to form large multicellular aggregates. This adhesive nature is enhanced with trypsin treatment without disruption of cell shape. Simultaneous addition of 20‐hydroxyecdysone and juvenile hormone results in diminished aggregate formation without preventing the changes in cell shape. These factors point to the possibility that 20‐hydroxyecdysone stimulates modifications in the cell surface that may be important during embryological differentiation.
Effect of developmental stage and body size on oxygen consumption of anuran larvae: A reappraisal
Authors: Feder Martin E. 
Published: June 2005

AbstractThe rate of oxygen consumption (V̇) varies throughout metamorphosis in larvae of anuran amphibians. To determine whether variation in V̇ is best explained by variation in developmental stage (S), dry body mass (M), or their interaction, I measured V̇ in developmental series of four species. In all species M accounted for most (59–90%) of the variation in V̇. Developmental stage has relatively little effect on V̇ after appropriate correction for differences in M among samples; S accounted for no more than 2% of the variation in V̇ in two genera (Bufo, Rana) and no more than 7% in a third (Hymenochirus). Late stages of metamorphosis were not examined in these larvae. In Xenopus larvae, S has little effect upon V̇ until late stages of metamorphosis, in which some but not all larvae had reduced V̇. The general relationship between V̇ and M in anuran larvae at 25°C is V̇ = 3.1 M0.827, where V̇ is in μl O2 STPD ·hr−1 and M is in mg. Because the exponent of M, 0.827, is less than 1.0, expression of V̇ as V̇ ·M−1 fails to correct for differences in M in statistical analyses. Most prior studies of larval V̇ require reevaluation because of statistical and methodological problems.
Flight muscle development in a hemimetabolous insect
Authors: Ready Neal E. , Josephson R. K. 
Published: June 2005

AbstractThe size of the metathoracic dorsal longitudinal flight muscle (DLM) in the cricket Teleogryllus oceanicus remains a constant proportion of metathoracic volume during most of nymphal life. Between the middle of the last nymphal instar and the fifth day of adult life, the DLM grows more rapidly than the metathorax, so that the ratio of DLM weight to metathoracic volume increases by a factor of 4. During this time, the DLM changes in appearance from translucent to pink, indicating an increase in mitochondrial content. Isometric twitch duration remains unchanged through late nymphal and early adult life (21 msec, onset to 50% relaxation, 25°C), as does fusion frequency (approximately 100 Hz, 25°C). During late adult life, DLM size decreases to 13% of the average for a young adult, isometric twitch duration doubles, and the DLM changes in appearance from pink to white. Since the flight motor program develops late in nymphal life and wings are produced only at the terminal molt, contraction kinetics that are characteristic of adult flight muscles appear to develop before the DLM receives the neural activity pattern for or becomes functional in flight. The appearance of adult contraction kinetics is apparently controlled by factors different from those that control increase in muscle size and mitochondrial content, since these processes are temporally separated during development.
The agouti suppressor (As) coat color mutation in mice: Developmental effects on the expression of agouti locus alleles
Authors: Poole Timothy W. 
Published: June 2005

AbstractThe alleles at the agouti locus in the mouse determine whether eumelanin or pheomelanin is synthesized by the follicular melanocytes. The agouti suppressor (As) mutation, which is closely linked to the agouti locus, reduces the amount of pheomelanin produced by whatever agouti alleles are present in the animal's genome. Previous developmental studies have indicated that the agouti alleles exert their influence on the follicular melanocytes via interactions between the developing dermis and epidermis. Using the techniques of dermal‐epidermal recombination of embryonic agouti suppressor (AsAw/AsAw), white‐bellied agouti (Aw/Aw), yellow (Ay/a), viable yellow (Auy/Auy), black and tan (at/at), and nonagouti (a/a) mouse skin, the present study demonstrates that 1) the dermis is responsible for the development of regional pigmentation patterns in white‐bellied agouti mice, and 2) the agouti suppressor mutation interferes with the expression of the white‐bellied agouti allele by acting on the dermis as well as the epidermis. In addition, this study provides further evidence for the role of the epidermis in the expression of the agouti locus alleles.
Chicken fetal antigen: Association with lymphoid development and differentiation
Authors: Dietert R. R. , Lewin H. A. , Qureshi M. A. , Kass L. B. 
Published: June 2005

AbstractRabbit antisera capable of detecting chicken fetal antigen (CFA) was prepared against 1‐day chick red blood cells (RBCs) and made specific by exhaustive adsorption with adult chicken peripheral RBCs (PRBCs) from the same strain. Microcytotoxicity was used to study the incidence of CFA on lymphocytes obtained from several organs at different developmental stages in the chicken. Lymphocyte‐associated CFA (LA‐CFA) determinants and erythrocytespecific CFA (ES‐CFA) determinants were distinguished through the use of adsorption analysis. The high incidence of CFA‐positive lymphocytes found in the fetal bursa and thymus was not equaled in the peripheral organs of the spleen, cecal tonsils, and gland of Harder. CFA expression on adult lymphocytes was restricted to the thymus and peripheral blood. It is suggested that these cells may represent a subpopulation of T lymphocytes. Adult spleen, cecal tonsils, and gland of Harder were virtually devoid of CFA‐bearing lymphocytes. At fetal developmental stages when greater than 94% of the bursal B cells were CFA‐positive, few, if any, of the highly differentiated Harderian B cells possessed CFA. It is suggested that LA‐CFA expression is dependent upon B cell differentiation and/or the bursa (central) vs gland of Harder (peripheral) microenvironment. The pattern of CFA expression on bursacytes is discussed in light of the properties of age resistance and bursal‐dependent target cells associated with virally induced lymphoid leukosis.