bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prey transport in the tiger salamander: Quantitative electromyography and muscle function in tetrapods
Authors: Reilly Stephen M. , Lauder George V. 
Published: June 2005

AbstractA quantitative analysis of the muscle activity patterns (motor patterns) used by tiger salamanders (Ambystoma tigrinum) during terrestrial feeding is presented to provide comparative data on motor output during prey transport in amphibians, compare prey transport motor patterns to those used during initial prey capture, and test the generality of previously proposed models of the feeding cycle in tetrapods.Simultaneous electromyographic and kinematic recordings during prey transport reveal four phases in the prey transport cycle. The Preparatory phase precedes prey transport with activity found mainly in muscles of the buccal floor (genioglossus, geniohyoideus, interhyoideus, and inter‐mandibularis), but with all muscles silent at the end of this phase. Prey transport occurs during the Fast Opening and Closing phases. The Fast Opening phase begins with near simultaneous onset of activity in all jaw and hyoid muscles, including anatomical antagonists such as the depressor mandibulae and adductor mandibulae. The subarcualis rectus one muscle is active during the Fast Opening and Closing phases of transport despite the lack of accompanying tongue projection and may function to stabilize the hyobranchial apparatus. The motor pattern of terrestrial prey transport differs considerably from that of initial prey capture, but appears to be similar to the motor pattern used during aquatic prey capture and hydraulic prey transport. We hypothesize that post‐metamorphic tiger salamanders accomplish terrestrial prey transport by retaining the larval motor pattern employed during suction feeding. The motor pattern and kinematics of prey transport in Ambystoma tigrinum differ in nearly all aspects from previous models of the generalized tetrapod feeding cycle.
Accumulation of 45Ca in the freshwater unionids Anodonta anatina and Unio tumidus, as influenced by water hardness, protons, and aluminum
Authors: Pynnönen Kirsi 
Published: June 2005

AbstractPrevious studies have revealed that freshwater bivalves subjected to acid stress suffer from severe electrolyte imbalance. A typical initial reaction is a transitory increase in concentration of Ca in the hemolymph during the first few days of exposure to such stress. Although this calcium obviously originates from the CaCO3 reserves in the clam, a possible ambient origin has never been ruled out. In the present study the uptake of Ca was studied under both circumneutral and acid conditions: two freshwater unionids, Anodonta anatina and Unio tumidus, were exposed to a bathing medium that contained 45Ca for a period of 24 hrs. In order to study the effect of the ambient Ca concentration on the efficiency of uptake of Ca, two media with different Ca concentrations (35 and 3.5 mg Ca/1; 4 × 106 cpm 45Ca/1 and 4 × 105 cpm 45Ca/1, respectively) were used. The role of the ingested food as a source of Ca was evaluated by feeding the clams with algae labeled with 45Ca. After the clams had been exposed for 24 hrs to 45Ca, the accumulation of 45Ca in the soft parts, including hemolymph, calcium concretions and glochidial larvae, was measured. Low pH (4–4.5) significantly decreased the uptake of 45Ca from the medium, whereas the addition of aluminum (900 μg/1) had only a minor effect on the uptake of 45Ca. The sites of accumulation of 45Ca under acidified conditions did not change: in all cases highest values for 45Ca concentration were measured in the gills, where the calcium concretions sequestered a large part of the 45Ca. A 90% decrease in the ambient Ca concentration caused a similar decrease in the uptake of 45Ca. Clams were able to utilize both dietary and waterborne Ca.
Precambrian oxygen levels, the sulfide biosystem, and the origin of the metazoa
Authors: Mangum Charlotte 
Published: June 2005

AbstractThe Berkner and Marshall hypothesis suggests that the atmosphere was virtually anoxic until the late Precambrian, and that the abrupt and coincidental appearance in the fossil record of the major animal phyla reflects the rise of PO2 to a level that supported animal life. In a more recent version the rise of PO2 is supposed to permit previously soft‐bodied animals, which had arisen during the anoxic period, to form fossilizable hard parts. The animal kingdom is conceived as fundamentally and primitively anaerobic and only secondarily aerobic. These ideas were incorporated into the Thiobiotic Theory, which supposes that a meiofauna endemic to the anoxic sulfide layer in marine sediments is a relict community of the pre‐normoxic Precambrian. This fauna consists of a number of simple metazoan phyla, including free‐living platyhelminths (but not cnidarians) which this theory regards as representatives of the ancestral Eumetazoa.The development of geological and ecological thinking about these hypotheses is summarized and the pertinent physiological evidence for and against them is briefly reviewed. I conclude that the available information does not support either the Berkner and Marshall Hypothesis or the Thiobiotic Theory, and is inconclusive on the identity of the ancestral animals. Moreover, several aspects of respiratory and metabolic biology are far more consistent with a fundamentally aerobic than anaerobic way of animal life.
Vitellogenesis in Anolis pulchellus: Induction of VTG‐like protein in liver explants from male and immature lizards
Authors: Morales Magda H. , Osuna Roberto , Sánchez Eric 
Published: June 2005

AbstractVitellogenin (VTG) synthesis has been described as an ideal system to study the hormonal regulation of gene expression. In Xenopus the molecular aspects of this control have been analyzed; however, in other non‐mammalian species such as reptiles, very few studies approaching this level have been undertaken. We report on the induction by estradiol‐17β of VTG‐like proteins in liver explants from adult males and immature male and female lizards (A. pulchellus). A concentration of 10−7 M was optimum for adult males while a higher concentration (10−6 M) is required for the immature animals. No differences were observed in the hormonal induction in male and female immature animals, suggesting that there are no sexual distinctions in the liver at this stage.The effect of the hormone in male liver appears to be primarily on mRNA synthesis, since increases in 3H‐uridine incorporation in total RNA were prevented by addition of 1 μg/ml of the RNA polmerase II inhibitor α‐Amanitin; however, rRNA synthesis was also increased as observed by agarose gel analysis. A 48 hr lag period was required for the detection of the intracellular as well as the secreted VTG‐like protein. Electrophoretical analysis of the secretory products revealed the induction of a group of phosphoproteins immunologically related to yolk lipovitellin whose molecular weights range from 116,000 to 200,000.
Regenerative capacity of forelimb buds after amputation in mouse embryos at the early‐organogenesis stage
Authors: Chan W. Y. , Lee K. K. H. , Tam P. P. L. 
Published: June 2005

AbstractThe ability of mouse forelimb buds at stage 1 (Wanek et al., '89a) of development to regenerate after amputation was investigated. The findings were as follows: 1. Outgrowths in the form of hillocks were found at the sites of amputation in 116 (95%) out of 122 embryos examined 24 hours after amputation. Examination of the amputated region after various intervals of time revealed that the outgrowths were established from flank tissues at the anterior and posterior borders of the wound. 2. Ectodermal thickening was found on the distal margin of the outgrowths in 21 (66%) out of 32 specimens examined. These thickenings were histologically similar to the apical ectodermal ridge (AER) present on the control limb buds. 3. Alkaline phosphatase activity was detected on the ectodermal thickening in 11 (79%) out of 14 experimental limb buds examined. The pattern of expression of alkaline phosphatase activity was similar to that observed in control limb buds. 4. There was no correlation between the size of the outgrowths and the presence of the ectodermal thickening or the enzymatic activity. The outgrowths developed despite the absence of ectodermal thickening and enzymatic activity, suggesting that the thickening and the presence of alkaline phosphatase are not crucial for the initiation and formation of the outgrowths. 5. Explants of the outgrowths, when grafted beneath adult kidney capsules, differentiated extensively into various tissues, which included bones, epiphyseal plates, skeletal muscles, and skin derivatives. Control explants also gave rise to the same spectrum of tissues. Hence, the flank tissues surrounding the site of amputation in E10 mouse embryos can regenerate to form a structure that is morphologically and histochemically similar to a limb bud and the mesenchyme within the structure is histogenetically competent to produce the variety of tissues that is normally found in the adult limb.
Specific, concentration‐dependent uptake of vitellin by the oocytes of Nereis virens (Annelida, Polychaeta) in vitro
Authors: Fischer A. , Rabien H. , Heacox A. E. 
Published: June 2005

AbstractOne purpose of this study was the development of methods for radioactive labeling and handling of the yolk protein of Nereis virens, another, the utilization of this tracer in nereid oocyte cultures to describe the kinetics and specificity of yolk protein uptake. Accumulation of labeled yolk protein by growing oocytes is linear over time, specific for yolk protein, and dependent on tracer concentration in the medium. Incorporation of yolk protein follows saturation kinetics which allows us to reproducibly determine the characteristics of this process. The apparent KM of ∼ 1 × 10−8 M indicates the high affinity of the transport system; the Vmax (160–400 pg protein/day × oocyte) reveals that transport of yolk protein into the nereid oocyte is very slow compared with a vertebrate system. The low Vmax corresponds to the very slow sexual maturation in this worm. Since nereid oocytes grow freely in the coelom, the experimental system described is suitable for a quantitative study of the transfer of biomass from soma to growing oocytes.
Slow locomotion in chameleons: Histochemical and ultrastructural characteristics of muscle fibers isolated from the iliofibularis muscle of Jackson's Chameleon (Chamaeleo jacksonii)
Authors: Mutungi Gabriel 
Published: June 2005

AbstractThe histochemical and ultrastructural characteristics of the fiber types present in the iliofibularis muscle isolated from Jackson's chameleon, Chamaeleo jacksonii, have been characterized in an attempt to explain the slow locomotion of these lizards. On the basis of their histochemical characteristics and nerve endings, four types of fibers were identified corresponding to the fast glycolytic (FG), fast oxidative glycolytic (FOG), slow oxidative (SO), and tonic fibers of other lower vertebrates. Three of these fiber types (FG, FOG, and SO) were focally innervated, and the other type (tonic fibers) multiply innervated. All the fibers isolated from the clear region and most of the fibers isolated from the yellow region had single well‐defined endplates. However, 20 to 28% of the fibers isolated from the yellow region possessed an average of 13 ± 0.6 endplates per fiber. The endplates in these fibers were poorly defined, 62 ± 2 μm in length, and 952 ± 40 μm apart. The mitochondrial volume of fibers isolated from the yellow region (8 ± 0.5%) was three times higher than that of fibers isolated from the clear region (2.45 ± 0.2%). In addition, the fibers isolated from the yellow region had three times the number of capillaries surrounding them as those recorded for fibers isolated from the clear region (1.95 ± 0.12 and 0.67 ± 0.09 capillaries per fiber, respectively). Fibers isolated from both regions had similar myofibrillar volume densities (91 ± 0.57, clear; 95 ± 0.87, yellow). © 1992 Wiley‐Liss, Inc.
Uptake of L‐ and D‐alanine by a brackish‐water Bivalve, Corbicula japonica, with special reference to their transport pathways and the salinity effect
Authors: Matsushima Osamu , Yamada Ayumu 
Published: June 2005

AbstractThe uptake of L‐ and D‐alanine by intact animals or isolated gills of a brackish‐water bivalve, Corbicula japonica, was investigated in relation to their transport pathways and the possible physiological roles. The animals took up L‐alanine at concentrations as low as 10 μM. Both the net transport and the influx were strongly affected by external salinity; animals acclimated to fresh water showed much lower rates of net transport and influx than did animals acclimated to 250 mOsm. Patterns of accumulation of 14C‐L‐alanine in different tissues of intact animals revealed that the gill was the principal site for the transport of the amino acid. Influx of both 14C‐L‐ and 14C‐D‐alanine into isolated gills was inhibited by α‐neutral amino acids, but not by α‐acidic or β‐amino acids; all α‐neutral amino acids examined (glycine, L‐glutamine, L‐leucine, L‐valine, and even D‐ and L‐alanine) inhibited the influx of D‐alanine more strongly than the influx of L‐alanine. Kinetic analysis of the influx indicated that D‐ and L‐alanine were transported via the same carrier(s), but that the carrier(s) had a higher affinity for L‐alanine than for D‐alanine. The transport mechanism appears to play a significant role in the net uptake of D‐ and L‐alanine or in the re‐uptake of the amino acids diffused from the integument according to the ambient concentrations of the substrates. © 1992 Wiley‐Liss, Inc.
Differential molt‐induced atrophy in the dimorphic claws of male fiddler crabs, Uca pugnax
Authors: Ismail Safaa Z. M. , Mykles Donald L. 
Published: June 2005

AbstractMolt‐induced atrophy was examined in the closer muscles of the dimorphic claws of the fiddler crab, Uca pugnax. In adult males, the major claw, which is about 30 times larger than the minor claw, contains primarily S1 fibers and some S2 fibers, while the minor claw contains exclusively S2 fibers. Ultrastructurally, both S1 and S2 fibers resembled slow fibers of other crustacean species: high ratios of thin:thick myofilaments, thickened Z‐lines, and myofibrils with long sarcomeres. However, the S1 fibers had higher thin:thick myofilament ratios (9:1 vs. 6:1), longer sarcomeres (6 μm vs. 4.5–5 μm) and fewer mitochondria than the S2 fibers. During proecdysis, the muscle of the major claw underwent a greater atrophy than that of the minor claw. Furthermore, atrophy of the major claw muscle was enhanced by the number of walking legs being regenerated. The weight of the major claw muscle in animals regenerating one walking leg decreased about 50%, while that in animals regenerating eight walking legs decreased about 67%. The weight of the minor claw muscle decreased about 25% in animals regenerating either one or eight walking legs. Changes in myofibrillar cross‐sectional areas paralleled the reductions in muscle mass. In S1 fibers, cross‐sectional area decreased 43% in animals regenerating one walking leg and 78% in animals regenerating eight walking legs. In S2 fibers, cross‐sectional area decreased 27% and 32%, respectively. Increases in the thick myofilament packing density and decreases in the thin:thick myofilament and actin:myosin heavy chain ratios suggest that this atrophy involves a preferential hydrolysis of thin myofilaments. The ultrastructural changes in S2 fibers from major and minor claws were similar, suggesting that the preferential atrophy of the major claw muscle results, at least in part, from a differential sensitivity of S1 and S2 fibers to factor(s) that trigger protein degradation. © 1992 Wiley‐Liss, Inc.
In vivo magnetic resonance imaging of the blue crab, Callinectes sapidus: Effect of cadmium accumulation in tissues on proton relaxation properties
Authors: Brouwer Marius , Engel David W. , Bonaventura Joseph , Johnson G. Allan 
Published: June 2005

AbstractNuclear magnetic resonance imaging (MRI) has been used to visualize the internal anatomy of a living blue crab. The resolution obtained in these studies was sufficient to distinguish individual organs by the differences in their proton densities and proton relaxation properties. T1 (spin‐lattice relaxation time)‐weighted imaging revealed the lipid‐rich nature of the hepatopancreas and gonadal tissue. To evaluate the effect of metal‐induced stress on the different organs, crabs were exposed to elevated levels of cadmium in their diet, which resulted in increased concentrations of both cadmium and copper in the hepatopancreas. The spin‐spin relaxation time, T2, of mobile protons in the metal‐exposed tissue was significantly greater than T2 in the control tissues. These measurements suggest that the excess copper in the exposed tissues was diamagnetic [Cu(I)], since the presence of paramagnetic copper [Cu(II)] would result in a decrease of observed T2 values. We hypothesize that the increased T2 value is a reflection of increased free water in the hepatopancreas. These studies show that magnetic resonance imaging is an important nondestructive tool for the study of morphological and physiological changes that occur in marine invertebrates in response to anthropogenic and natural stresses. © 1992 Wiley‐Liss, Inc.
Diisopropylfluorophosphate inhibits acetylcholinesterase activity and disrupts somitogenesis in the Zebrafish
Authors: Hanneman Eric H. 
Published: June 2005

AbstractAcetylcholinesterase (AChE) activity, localized histochemically, appeared in the nuclei of presumptive somitic mesodermal cells prior to the onset of somitogenesis. AChE activity appeared in a rostro‐caudal sequence, in cells located the equivalent of five somite lengths caudal to the last formed somite. To investigate whether AChE activity was required for somitogenesis, several inhibitors of AChE activity were tested for their ability to block somitogenesis.Diisopropylfluorophosphate (DFP), a broad spectrum inhibitor of serine proteases and related enzymes, was the only AChE inhibitor tested that disrupted somitogenesis. Gastrulae at 50% epiboly exposed continuously to DFP at concentrations between 40 μM and 90 μM completed epiboly, but exhibited a dose‐dependent decrease in the number of somites formed, and a parallel decrease in the caudal extent of somite innervation, by 24 hours post‐fertilization (h).Fifteen somite (15h) embryos exposed to DFP at the ED50 of 70 μM for 3 hours, followed by recovery to 24h, developed abnormal somites. Approximately five normal somites formed after drug treatment before the first abnormal somite formed. The abnormal somites corresponded in location to that area of the presumptive somitic mesoderm that would have initiated AChE activity while the DFP was present. While exposed to 70 μM DFP, presumptive somites formed and motoneurons extended processes that had initiated AChE activity at the time of treatment with DFP, although at a slower than normal rate. However, embryos exposed to 1 mM DFP for 30 minutes at both the 5 and 15 somite stages, followed by recovery to 24h, developed the normal number of somites but were reduced in the caudal extent of somite innervation, and occasionally developed abnormal primary motoneurons. As with the abnormal somites, the abnormal motoneurons would have initiated AChE activity while the DFP was present.Presumptive somitic mesoderm unable to initiate AChE activity due to inhibition by DFP developed abnormally. While the effects of DFP are not limited to inhibiting AChE, the data support the “clock and wavefront” model proposed for somite formation, and support the hypothesis that AChE activity has a role in somitogenesis in zebrafish. © 1992 Wiley‐Liss, Inc.
Genetic linkage analysis of the murine developmental mutant velvet coat (Ve) and the distal chromosome 15 developmental genes Hox‐3.1, Rar‐g, Wnt‐1, and Krt‐2
Authors: Hart Charles P. , Compton John G. , Langley Stephen H. , Hunihan Lisa , LeClair Kenneth P. , Zelent Arthur , Roderick Thomas H. , Ruddle Frank H. 
Published: June 2005

AbstractWe have identified restriction fragment length polymorphisms between Mus musculus and Mus spretus for the Chromosome 15 loci Hox‐3, Wnt‐1, Krt‐2, Rar‐g, and Ly‐6. We followed the inheritance of these alleles in interspecific genetic test crosses between velvet coat (Ve) heterozygotes and M. spretus. The results suggest a gene order and recombination distances (in cM) of Ly‐6—22—Wnt‐1—2—Ve/Krt‐2/Rar‐g—3—Hox‐3. No recombination was found between Ve, Krt‐2, and Rar‐g. The data also provide evidence for the hypothesis of a large‐scale genomic duplication involving homologous gene pairs on mouse Chromosomes 15 and 11. © 1992 Wiley‐Liss, Inc.
MHC class II molecules and immunoglobulins on peripheral blood lymphocytes of the bottlenosed dolphin, Tursiops truncatus
Authors: Romano Tracy A. , Ridgway Sam H. , Quaranta Vito 
Published: June 2005

AbstractThe immune system of marine mammals is of comparative interest because of its adaptation to the aquatic environment. Little information, however, is available on its cellular and molecular components. Here, we used a cross‐reactive antibody to MHC class II molecules and an immunoglobulin‐specific antiserum for identifying these molecular species on lymphocytes of the bottlenosed dolphin, Tursiops truncatus. Limited structural analyses indicated that class II molecules and immunoglobulins of dolphin closely resemble those of other vertebrates. In the peripheral blood of most land mammals both class II and immunoglobulins are usually found on B but not T lymphocytes. Expression of immunoglobulins on dolphin peripheral blood lymphocytes suggests a ratio of B cells to T cells comparable to that of land mammals. However, unlike the majority of land mammals, virtually 100% of the peripheral T cells display pronounced expression of class II molecules, generally considered an indication of T cell activation. It is therefore possible that the physiology of T cell activation has unusual attributes in the dolphin. It is especially interesting that some land mammals, namely swine (ungulates) and dogs and cats (carnivores), also express class II molecules on peripheral blood T lymphocytes. Since ungulates and carnivores are thought to share a common distant ancestry with toothed whales, the evolutionary history may be more relevant than the environmental history in determining these unusual attributes. © 1992 Wiley‐Liss, Inc.
Incidents of rejection and indifference in Fu/HC incompatible protochordate colonies
Authors: Rinkevich Baruch , Weissman Irving L. 
Published: June 2005

AbstractWe test here for the existence of specific alloimmune memory in the rejection responses of the colonial tunicate Botryllus schlosseri. Colony specificity in these organisms is controlled by the Fu/HC locus. Rejection occurs only between colonies that do not share any allelic determinant at this locus. Two sets of experiments were conducted: 1) Forty‐nine pairs of nonfusible oozooids were interacted naturally along a period of several months. They rejected, disconnected, and in 20% of the cases, interacted again. 2) Repeated colony allorecognition assays were done on 15 pairs of interacting subclones (up to 5 consecutive tests/pair). Major results indicate: 1) Not all ampulla‐ampulla interactions resulted in necrotic areas, points of rejection (PORs). 2) A full repertoire of PORs was attained within the first 10 days. Thereafter, no more PORs were added. 3) The outcome of indifference (cases where ampulla‐ampulla contacts did not result in rejection) was repeatedly recorded in multiple tests, and its frequency increased in the secondary and tertiary tests along a set of 5 consecutive tests. It is concluded that allospecific memory, as measured by an accelerated production of PORs and amplification in their number, was not characteristic of the Botryllus rejection phenomenon, which, however, reveals the qualities of a low responder. These results are discussed in the light of some aspects of tolerance in the mammalian system. © 1992 Wiley‐Liss, Inc.