摘要:

AbstractIncorporation of3H‐ethanolamine in phosphatidylethanolamine (PE) and in phosphatidylcholine (PC) isolated from different tissues of crabCarcinus maenaswas analyzed at environmental temperature of 13°C and 23°C. The stepwise N‐methylation of PE to PC occurs only in the hepatopancreas, its importance being greater in animals living at 23°C. The hemolymph‐hepatopancreas exchange of PC plays an important part on the regulation of the hepatopancreas PC pool. Also, the environmental temperature strongly influences PC distribution between hemolymph and hepato

ISSN:0022-104X    

DOI:10.1002/jez.1402240302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe Sephadex G‐200 gel filtration fractions C1 to C6 of the water‐soluble lens proteins ofCalotes versicolorhave been characterized by polyacrylamide gel electrophoresis (PAGE), 7 M urea PAGE, SDS PAGE, and immunological tests. C1 fraction, an α‐crystallin which cross‐reacts with chick α, has very low amount of B chains. It shows two bands in SDS PAGE, one strong and another weak. C2 and C3 fractions, both of which partially cross‐react with chick β ‐crystallins, are largely similar but not identical. C2 in SDS PAGE produces a faint band with a molecular weight of 54,500, which suggests that C2 may either contain a small amount of δ‐crystallin in addition to βH crystallin or thatCalotesβH has a high molecular weight subunit like human βH; however, in immunological tests no material cross‐reacting with chick δ was seen. C4 and C5 are low molecular weight, monomeric, and basic proteins which in all probabilit

ISSN:0022-104X    

DOI:10.1002/jez.1402240303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIn the Nemertina both neurosecretory cells in the cerebral ganglia and neuroglandular structures (cephalic glands and cerebral organs) have been found to be responsive, on a cytological level, to changes in the osmolality of the worm's environment. However, the volume or osmoregulatory capacities of these worms are scarcely known. The present study examines water, ion, and volume regulation in an intertidal nemertine and the effects of removal of the cerebral ganglia and the cephalic glands on these parameters.Control, sham‐operated, and decerebrated (ablated)Procephalothrix spiraliswere acutely transferred to diluted seawaters. Osmolality and Na, K, and Cl (mEq/liter) concentrations were determined in total tissue water after various exposure periods. Extracellular volume was determined, in vitro, as the fraction of the total tissue water in which14C‐polyethylene glycol was distributed.Control, sham‐operated, and ablatedP. spiralisall responded to diluted seawaters in the same manner with no significant difference among groups. In diluted media, the worms demonstrated hyperosmotic conformity. Tissue osmolality decreased rapidly in all groups at similar rates indicating no effect of ablation on integumental water permeability. Significant volume regulatory responses were observed in all worms starting 15 minutes after exposure. Based on the very small extracellular volume (∼5% of total body water) ofP. spiralis, measured volume regulatory events in this species primarily reflect intracellular phenomena. Initially, osmolality decreased while water content (gm H20/gm solute free dry weight) increased. During this period, volume regulation was accomplished by the elimination of Na, Cl, and unmeasured solutes (μmoles or μosmoles/gm s.f.d.w.) which limited water gain. Subsequently, osmolality was constant and all worms demonstrated a slow regulatory volume decrease. The solutes that accompanied volume loss were also Na, Cl, and substantial amounts of unmeasure

ISSN:0022-104X    

DOI:10.1002/jez.1402240304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis study correlates endogenous levels of cAMP and cGMP with their immunohistochemical localization during chondrogenic differentiation of C57B1/6J mouse limb mesenchyme in vivo and in vitro. A transient decrease in cGMP but not cAMP was found from days 12 to 13 in vivo correlating with early stages of chondrogenesis in the developing limb. Intracellular levels of both cAMP and cGMP in high density limb mesenchyme cultures increased 25% after 24 hr in culture when aggregate and nodule formation was detectable. When cells were seeded at different initial plating densities to delay the onset of aggregate and nodule formation, increased levels of intracellular cAM Pcorrelated temporally with the appearance of nodules. Both cyclic AMP and cGMP were immunohistochemically localized in perichondrial cells and chondrocytes in vivo and in vitro. Therefore, (1) cAMP levels correlated temporally with the appearance of chondrogenic cells and (2) cAMP and cGMP were immunohistochemically localized to chondrogenic cells.These data indicate that fluctuations of both cAMP and cGMP levels may be involved in limb cartilage differentiation. Although increases in both nucleotides were found to correlate with the onset of chondrogenesis in vitro, in vivo data suggest that the amount of cAMP relative to cGMP rather than the absolute amount of an individual cyclic nucleotide may be more significant in modulating differentiation.

ISSN:0022-104X    

DOI:10.1002/jez.1402240305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractOsteoclasts were isolated from the endosteal surface of day 19 embryonic chick tibias by mild trypsinization. Osteoclast enrichment was achieved by passing cell suspensions through Nitex screening of selective sizes, including the eventual selective retention of osteoclasts on 12 μm polycarbonate filters or by sequential sieving through Nitex screens and fractionation on Percoll gradients. The enrichment procedures produced osteoclast populations of 50–75% based on morphological criteria with the latter isolation method providing populations with less matrix debris. The results of light microscopy, transmission and scanning electron microscopic observations indicate that osteoclasts can be maintained in culture for up to 10 days with retention of osteoclast morphology. This morphology includes a specialized ruffled plasma membrane, large numbers of mitochondria, lysosomes, as well as a multinucleated cytoplasm. Furthermore, acid phosphatase and butyrate esterase histochemical measurements support these morphological observations. In addition, chick hatchling circulating monocytes were isolated and purified by Ficoll‐hypaque gradient centrifugation with subsequent adhesion to glass petridishes. With time in culture, these cells form multinucleated cells, but lack the ultrastructural complexity of the isolated osteoclasts. This report describes a unique culture system to study osteoclast function and illustrates the similarities and differences of this system to the monocyte‐to‐giant cell cultur

ISSN:0022-104X    

DOI:10.1002/jez.1402240306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractOsteoclast resorption of bone matrix during bone development is preceded by cell attachment to bone. An in vitro assay is described that measures adhesion of isolated osteoclasts and their presumed progenitor cell, the monocyte, to embryonic chick bone. Osteoclasts were isolated from day 19 chick tibia and enriched. Circulating chick hatchling monocytes were purified by Ficollhypaque sedimentation and attachment to plastic. Isolated cells were labeled with (32P)‐KH2PO4to quantitate cell attachment. In one series of experiments, labeled cells were inoculated into vessels containing day 19 tibias with either endosteal or periosteal bone surface exposed. Labeled cells were also inoculated into chambers containing day 6 (cartilage cores), day 12 (bone and cartilage cores), or day 19 embryonic tibias (bone). Cultures of stage 24 chick limb mesenchyme and embryonic chick skin fibroblasts served as controls. Results demonstrate that twice as many osteoclasts and monocytes adhere to bone as compared to fibroblasts and stage 24 limb mesenchymal cells. Furthermore, there does not appear to be selective adhesion to the endosteal as compared to periosteal bone surfaces. When the data is calculated on the basis of cell attachment per area of each substrate, the day 12 cores had slightly higher number of osteoclasts and monocytes attached compared to day 19 bones; day 6 cartilage cores bound few cells. These observations suggest that osteoclasts and monocytes have a high affinity to bone which seems to be influenced by the developmental age and composition of the substrat

ISSN:0022-104X    

DOI:10.1002/jez.1402240307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe mode of differentiation of epidermal melanocytes was studied by ultrastructural cytochemistry in the skin of newborn mice of strain C57BL/10J. From observations of epidermal melanoblasts and melanocytes, stage I melanosomes, including both unit membranes and inner matrices, appear to be formed from Golgi vacuoles or rough endoplasmic reticulum (RER). Stage I melanosomes were positive to ammoniacal silver‐nitrate reaction in the melanoblasts of 1‐day‐old mice. All stages of melanosomes were similarly positive in the differentiating melanocytes of 2‐day‐old mice. However, Golgi apparatus, RER, and vesicles were negative. Therefore, it is conceivable that structural proteins, originated from Golgi vacuoles or RER, are developed into specialized proteins and are detected by this reaction in stage I melanosomes. Stage I melanosomes were dopa‐negative in the melanoblasts. Stage I and II melanosomes were similarly negative in the differentiating melanocytes. Thus, the melanoblasts are thought to begin production of stage I melanosomes prior to the onset of tyrosinase activity. In the differentiating melanocytes, dopa‐melanin depositions were observed in stage III and IV melanosomes,transGolgi saccules, and small vesicles derived from these saccules, but not in RER. These vesicles were in contact with, or fused to, melanosomes. These findings suggest that tyrosinase may be transferred by Golgi vesicles into stage I and II melanosomes originating from Golgi va

ISSN:0022-104X    

DOI:10.1002/jez.1402240308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe male mongoose,Herpestes auropunctatus, displays a distinct seasonal reproductive rhythm in environments which show minimal changes in daylength. This investigation was designed to evaluate whether the reproductive system of the male mongoose was responsive to photoperiodic manipulations. Four experiments were conducted; two during the breeding season, one during the inactive season, and one during the recrudescence phase. Serum androgen levels and reproductive organ weights were similar in males exposed to either short (6L:18D) or control photoperiods (14L:10D) when the photoperiodic adjustment was initiated in April; however, serum androgen levels were significantly depressed after 60 days exposure to short photoperiods as were weights of prostate glands when the photoperiodic manipulation was initiated in May. An increase in the number of hours of light per day during the inactive season did not affect serum androgen levels or reproductive organ weights. Exposure to a very short photoperiod (2L:22D) during the recrudescence phase delayed, but did not prevent, the increase in serum androgen levels. Although the reproductive system of the male mongoose is responsive to daylength adjustments, the response is less pronounced when compared to the effects of photoperiod in other seasonal breeders.

ISSN:0022-104X    

DOI:10.1002/jez.1402240309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractOvulated rat oocytes were observed to activate spontaneously during in vitro culture. The possible mechanisms involved in this activation were studied by culturing oocytes at various times (0–6 hr) after ovulation, in different media, and for different incubation periods (0–5 hr). Activated oocytes extruded the second polar body within 60 to 90 min of culture. Following 3 to 4 hr of culture chromosomes were scattered throughout the cytoplasm; however, no pronuclear formation was observed. Neither time after ovulation nor incubation in different media affected the rate of activation. The length of time the oviducts remained in the animal after cervical dislocation, however, significantly (P<0.01) affected the rate of activation. Oocytes obtained as rapidly as possible had an activation rate of 21% during in vitro culture, whereas oocytes obtained from oviducts which remained in the animal for 5 min after cervical dislocation had an activation rate of 94%. Therefore, exposure to changing oviductal conditions following cervical dislocation appears to be the critical factor influencing spontaneous activation of metaphase II rat oocytes during in vitro culture. Our studies demonstrate that rat oocytes can spontaneously activate during in vitro culture, a factor which may affect the fertilizability of the ooc

ISSN:0022-104X    

DOI:10.1002/jez.1402240310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractWhereas abdominal temperatures have no effect on spermatogenesis in testicondid mammals but inhibit the process completely in scrotal mammals, the inguinal testes of the naturally cryptorchid musk shrew and degu have been found to display an intermediate response. Twelve to 18 weeks after transposition to the abdomen (and so about 1.5°C above its normal inguinal temperature) the weight of the testis was reduced by 27% (musk shrew) and 52% (degu). Nonetheless, spermatogenesis continued in both, though at a lower rate and with a greater proportion of abnormal spermatozoa formed. The ultrastructural anomalies evident in some spermatids of the degu testis transposed to the abdomen were reminiscent of those seen commonly in the germinal epithelium of “normal” men. Natural cryptorchids may thus be useful models in which to discover whether spermatogenesis at a temperature somewhat above the norm for the species compromises the ability of fertilizing spermatozoa to support normal development.The fact that deep‐body temperature induces only a partial suppression of function in the inguinal testis of natural cryptorchids shows that there is no absolute distinction between the scrotal and ascrotal states among mammals with respect to the temperature sensitivity of the testis. That visible sensitivity seems more likely to reflect the adaptation of the metabolically dynamic germinal epithelium to function optimally at the temperature of the location to which the testis migrates, rather than any fundamental incompatability between spermatogenesis and the temperature imposed by homeothermy. External migration of the testis itself may originally have helped the sperm storage region of the associated epididymis to project from and so attain a cooler environment than that beneath the body s

ISSN:0022-104X    

DOI:10.1002/jez.1402240311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY