bluuebunny/crossref_metadata_2025_split huggingface dataset:
A strategy for an improved separation of mammalian spermatids
Authors: Loir Maurice , Lanneau Maryvonne 
Published: February 2005

AbstractA collection procedure has been developed to improve the homogeneity of mammalian spermatid populations separated by elutriation. Trypsinizied ram testis cells were elutriated at 18C. Every cell population was eluted by progressive changes in the flow rate and/or rotor speed, instead of by abrupt changes, to reduce the contamination by cells from the next population. Pure populations were collected alternating with mixed populations corresponding to the overlap between two adjacent pure populations. Furthermore, each pure population was collected into two subfractions, the second of which, contamined by cells from the following population, was pooled with the following fraction. In less than 2 hr after castration, three populations of at least 1 × 108 viable round or elongated or elongating spermatids were obtained with respective purities of 95%, 82%, and 99% of the nucleated cells. In addition, two mixed populations containing only two adjacent spermatid types (round plus elongating spermatids: 98%; elongated plus elongating spermatids: 98%) were obtained, as well as a population containing around 60% pachytene spermatocytes.
Sperm motility in the horseshoe crab. IV. Extracellular ions and intracellular pH are not mediators of motility initiation
Authors: Clapper David L. , Epel David 
Published: February 2005

AbstractUpon dilution into sea water, Limulus spermatozoa undergo a brief flurry of motility (duration < 60 sec), after which they are nonmotile until encountering a sperm motility initiating peptide (SMI) that emanates from eggs. Utilizing highly purified SMI extracts and simplified seawater formulations (from which individual ions have been deleted), we found that no specific extracellular ion is required for either dilution‐initiated or SMI‐initiated motility. Indeed, deletion of one ion (Na+) produced dilution‐initiated motility of very long duration (several hours). When motility is initiated by SMI (in normal seawater) there is an increase in intracellular pH (pHi), as indicated by the fluorescent probe, 9‐amino acridine; however, this pH, change is not a trigger for motility. As a more general method examining ion movements, the fluorescent probe diS‐C3‐(5) was used to qualitatively measure changes in the membrane potential of spermatozoa. Although crude SMI extracts caused membrane depolarization, further purification resulted in an almost complete separation of this activity from SMI, thus showing that SMI activation is apparently an electroneutral event. (The membrane‐depolarizing factor has a molecular weight > 30,000 and does not initiate acrosome reactions.) Experiments utilizing the ionophore A23187 and Ca+2‐blocking agents (verapamil and TMB‐8) provided tentative evidence that mobilization of intracellular Ca+2 may be required for motility initiation. These results show that neither changes in pHi nor the influx of specific extracellular ions are direct mediators of SMI‐initiated motility; however, experiments with pharmacologic agents indicate a possible role for intracellular Ca+2.
Mitochondrial movement during the ascidian sperm reaction
Authors: Lambert Charles C. , Lambert Gretchen 
Published: February 2005

AbstractThe ascidian sperm reaction, Which involves swelling, migration, and loss of the single large mitochondrion, can be triggered in vitro by raising the seawater pH to 9.3 or lowering Na+ to 20 mM, but only if the sperm are allowed to attach to a suitable Substate. Mitochondrial translocation does not usually occur in the absence of sperm attachment. Extracellular Ca2+ is necessary for triggering the reaction with low Na+ but not high pH; however, the intrecellular Ca2+ blocker, TMB‐8, inhibits high pH‐induced mitochondrial movement in the absence of extracellular Ca2+. After swelling, the mitochondrion fluoresces in the presence of chlortetracycline, suggesting that Ca2+ becomes membranebound after activation. Elevated cAMP and theophylline both inhibit mitochondrial move ment but not sperm motility. The antiactin drug cytochalasin B(10μM) and the calmodulinblocking drugs TFP (1 μM) and W‐13 (10 μM) block mitochondrial movement, suggesting roles for actin and calmodulin in mitochondrial movement. A model is proposed relating intracellular alkalinization, Ca2+ influx, actin, myosin, and calmodulin in mitochondrial translocation.
N‐acetyl‐β‐D‐glucosaminidase activity in the cortical granules of Xenopus laevis eggs
Authors: Greve L. Carl , Prody G. A. , Hedrick Jerry L. 
Published: February 2005

AbstractThe glycosidase activities associated with Xenopus laevis eggs were determined using p‐nitrophenyl glycosides as substrates. The egg lysate contained significant amounts of α‐fucosidase, N‐acetyl‐β‐D‐galactosaminidase, and α‐mannosidase activities with smaller amounts of other glycosidase activities, including N‐acetyl‐β‐D‐glucosaminidase. A cortical granule exudate obtained from ionophore‐activated dejellied eggs contained predominantly glucosaminidase activity with only trace amounts of other glycosidase activities. Perivitelline space material obtained from activated or fertilized jellied eggs contained only glucosaminidase activity. Using cytochemical staining procedures, glucosaminidase activity was present in the perivitelline space and the inner aspect of the jelly coat after fertilization or activation of the egg, but not before. The rate of glucosaminidase activity released from activated eggs occurred with the same kinetics as the cortical reaction. The cortical granule and noncortical granule glucosaminidase activities had different electrophoretic mobilities as determined by disc gel electrophoresis. Thus, the Xenopus laevis egg has two N‐acetyl‐β‐D‐glucosaminidase activities, one associated with the cortical granules and the other associated with the noncortical granule compartment of the cell. The cortical granule enzyme released from the egg at fertilization may function in altering the egg's penetrability to supernumerary sperm.
Ovostatin, an endogenous trypsin inhibitor of sea urchin eggs: Purification and characterization of ovostatin from eggs of the sea urchin, Strongylocentrotus intermedius
Authors: Yamada Yuji , Aketa Kenji 
Published: February 2005

AbstractA trypsin inhibitor, termed ovostatin, has been purified approximately 265‐fold with 82% yield, from unfertilized eggs of the sea urchin Strongylocentrotus intermedius, using trypsin coupled Sepharose 4B as an affinity column for chromatography. The isolated ovostatin is homogeneous in sodium dodecyl sulfate/polyacrylamide gel electrophoresis, the estimated molecular weight being 20K–21.5K. Ovostatin inhibits preferentially trypsin‐like endogenous protease purified from the eggs of the same species and bovine pancreatic trypsin and also bovine pancreatic chymotrypsin. Values of IC50 (amount causing 50% inhibition of enzymes) for trypsin‐like protease purified from eggs of the same species, bovine pancreatic trypsin, and bovine pancreatic chymotrypsin, are 0.91 ± 0.13 μg/ml (4.55 ± 0.65 × 10−8 M), 3.0 ± 0.28 μg/ml (1.5 ± 0.14 × 10−7 M), and 4.8 ± 0.2 μg/ml (2.4 ± 0.1 × 10−7 M), respectively, in the experimental condition used. Kinetic studies indicate that ovostatin is a noncompetitive inhibitor of trypsin. The inhibitor is relatively heat labile. NaCl (0.025–0.01 M) enhances the inhibitor activity, whereas KCl is inhibitory. Ovostatin requires a low concentration of Ca2+ for activity. The activity is higher in unfertilized eggs than in fertilized eggs; total activity and specific activity in unfertilized eggs is about 1.67‐fold and 1.85‐fold higher than those in fertilized eggs, respectively. We believe that ovostatin may regulate the function of the cortical granule protease and other trypsin‐like proteases that are activated in sea urchin eggs during fertilization.
Ultrastructural studies of the early events of the human sperm acrosome reaction as initiated by human follicular fluid
Authors: Yudin Ashley I. , Gottlieb Wayne , Meizel Stanley 
Published: February 2005

AbstractIt has been suggested that the morphology of the human sperm acrosome reaction (AR) is markedly different from that of other mammalian sperm. The present study examines the fine structural events of the early stages of the human sperm AR as initiated by preovulatory human follicular fluid. Human sperm, capacitated in vitro for 6 hr at 40°C (90% motility) were diluted with equal volumes of follicular fluid before fixing in cacodylate‐buffered glutaraldehyde at 5, 10, 15, 20, and 180 sec. Fixed sperm were treated with either tannic acid or thiocarbohydrazine and OsO4. Over 2,000 sperm were viewed. By 5 sec, 2% of the sperm had initiated the AR. By 15 sec, 8% of the sperm were in some stage of the reaction, and after 180 sec 40% of the sperm had completed the acrosome reaction. The initial stages of the human AR are characterized by a swelling or decondensation of the acrosomal matrix. The fusion between the plasma membrane and outer acrosomal membrane begins at the most anterior tip of the head and progresses toward the equatorial segment. Fusion and fenestration ended at the equatorial segment. With thiocarbohydrazine + OsO4 fixation the fused membranes are distinct hybrid vesicles with the outer acrosomal membrane being far more electron dense. The acrosomal matrix is retained by 20 sec, but by 180 sec the matrix is completely dispersed, even when viewed after tannic acid fixation. Also by 180 sec, vesicles were being progressively lost. It is therefore concluded that the morphology of the human sperm AR, as initiated by human follicular fluid, is not unique, but is similar to that described for other mammalian sperm.
Effect of exogenous hormones on the ovulation of primary and secondary oocytes in LT/Sv strain mice
Authors: Speirs S. , Kaufman M. H. 
Published: February 2005

AbstractLT/Sv strain mice ovulate both primary and secondary oocytes. These are fertilizable and give rise to digynic triploid and normal diploid conceptuses, respectively. A previous study [Kaufman and Speirs, 1987] had indicated that just over 20% of embryos recovered on the 10th day of gestation from spontaneously ovulating females had a triploid chromosome constitution. This value was considerably lower than might have been expected by extrapolation from earlier studies in which LT/Sv mice had been given exogenous gonadotrophins. In the present study, therefore, cytogenetic analysis of fertilized eggs was performed at the first cleavage mitosis in (1) spontaneously ovulating females mated to F1 hybrid males, and (2) superovulated females mated to similar males. Additional females from group (1) were autopsied on the 10th day of gestation, and the ploidy of embryos isolated at this stage of gestation was determined. Exposure to exogenous gonadotrophins significantly increased the proportion of eggs that were ovulated as primary oocytes (34.4%), compared to the situation observed following spontaneous ovulation (24.4%). All the triploids encountered in both series were of the digynic type and characteristically (for LT/Sv mice) had an oocyte‐derived set with 40 chromosomes present, and a sperm‐derived set containing 20 chromosomes. Similar numbers of eggs were recovered from spontaneously ovulating females on the 1st and 10th days of gestation, and the incidence of triploidy observed on the 10th day was 22.1%. The influence of exogenous hormones in increasing the “spontaneous” level of triploidy in LT/Sv and in other strains of mice is briefly reviewed.
Lipid interactions with in vitro development of mammalian zygotes
Authors: Waterman R. A. , Wall R. J. 
Published: February 2005

AbstractRabbit zygotes were tested for their ability to sequester radiolabeled acetate, oleate, and arachidonate in intracellular lipid. Radiolabeled arachidonic acid was concentrated 170 ± 28‐fold (mean ± SEM) and oleic acid was concentrated 105 ± 26‐fold in zygotic lipids during 6 hr of culture when compared with the initial concentrations in culture medium. Acetate was not concentrated into lipids by cultured zygotes. Both long chain fatty acids were incorporated mainly as triglyceride. Polydimethylsiloxane fluid, used to cover the microdroplets of medium during culture, demonstrated lipophilic properties. This characteristic was utilized to indirectly transfer lipids to culture medium, permitting examination only of lipoidal properties of test extracts on embryonal development. For rabbit zygotes, blood plasma extract was detrimental and whole blood extract was beneficial for embryonal cleavage rates during the first 24 hr of culture. A higher proportion of mouse zygotes developed to blastocysts when cultured in modified Ham's F‐10 medium compared to BMOC medium, and this difference was negated by inclusion of a lipid extract prepared from rabbit oviductal fluid in the culture system. Comparison of fatty acid analyses of the lipid extracts with development rates of zygotes suggests that modified rates of embryo development may be associated with ratios of individual fatty acids presented to the culture medium rather than with the presence of any single fatty acid.
Ultrastructural observations on gamete interactions using micromanipulated mouse oocytes
Authors: Cummins J. M. , Edirisinghe W. R. , Odawara Y. , Wales R. G. , Yovich J. L. 
Published: February 2005

AbstractCumulus‐free mouse oocytes were subjected to zona opening by cracking with microhooks (ZC) or acid drilling (ZD) and fixed 30–90 min after insemination (105 pre‐capacitated motile sperms/ml). Ultrastructural observations were made on serially thin‐sectioned oocytes: 15 ZC and 12 ZD. The zona lesion in ZC oocytes was a clean cut, whereas in ZD oocytes it formed a patchy area of partial zona loss, with reduced microvillar height on the underlying oocyte surface. Spermatozoa were observed within the perivitelline space and partially fusing with the oocyte after 30 min in both situations. Only acrosome‐reacted sperm heads were observed to fuse: acrosome intact forms were generally in contact with the zona pellucida, either with the inner or outer surface. Acrosome‐intact spermatozoa were also observed deeply embedded in the zona matrix, possibly indicating surface enzyme activity preceding the membrane fusion events of the acrosome reaction proper. The observations are consistent with the need for spermatozoa to make contact preferentially with the zona pellucida during the course of the acrosome reaction.
Some benefits of Fe doped less dislocated GaN templates for AlGaN/GaN HEMTs grown by MOVPE
Authors: Bougrioua Z. , Azize M. , Lorenzini P. , Laügt M. , Haas H. 
Published: February 2005

AbstractStrategies for maintaining a low threading dislocation density in highly resistive GaN layers grown by MOVPE on sapphire or SiC substrates using Fe modulation doping are presented. Sheet resistances as high as 108 Ω□ for dislocation densities lower than 8 × 108 cm–2 have been obtained. 2DEGs created at the AlGaN/GaN:Fe interface have good confinement while the low dislocation density benefits the mobility: room temperature values up to 2170 cm2 V–1 s–1 have been obtained for a carrier density of 9.3 × 1012 cm–2. A simplified transport model is proposed to fit the experimental data. Processed transistors showed good channel control and DC performance. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect morphology and strain of CVD grown 3C–SiC layers: effect of the carbonization process
Authors: Méndez D. , Aouni A. , Morales F. M. , Pacheco F. J. , Araújo D. , Bustarret E. , Ferro G. , Monteil Y. 
Published: February 2005

AbstractThe heterostructure formed by cubic silicon carbide/silicon (3C–SiC/Si) is very promising as substrate for cubic III‐N growth and for SiC devices. Optimized Si substrate carbonization process before the epitaxial growth of SiC, leads to a higher quality of the layer. In this paper, transmission electron microscopy is used to analyze the defect morphology and strain of SiC layers grown by chemical vapor deposition on two differently carbonized substrates, with tensile and compressive strain state. Misfit dislocations, stack‐ ing faults and antiphase domains are observed in this heteroepitaxial system. Irrespective of the substrate used, the epitaxial relationship between Si and SiC is good. However, the grain misorientation of the mosaic structure and the strain of the overgrowth layer depend drastically on the carbonization conditions of the silicon substrate. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Semantics of under-determined expressions
Authors: Larsen Peter Gorm , Hansen Bo Stig 
Published: February 2005

Abstract
Some specification languages, such as VDM-SL, allow expressions whose values are not fully determined. This may be convenient in cases where the choice of value should be left to a later stage of development.
We consider a simple functional language including such under-determined expressions and present a denotational semantics for the language along with a set of proof rules for reasoning about properties of under-determined expressions. One of the specific problems considered is the combination of under-determinedness and a least fixed point semantics of recursion. Soundness of the proof rules is also discussed.
Structured development of a virtual shared memory system
Authors: Seidel Karen , Gardiner Paul 
Published: February 2005

Abstract
In this paper we formalise three different views of a virtual shared memory system and show that they are equivalent. The formalisation starts with five basic component processes specified in the language of CSP [Hoa85], which can be adapted as necessary by two operations called labelling and clamping, and are combined in two basic ways: either they are chained, so that the output of one component becomes the input of the next, or they are put in parallel, so that their communications are arbitrarily interleaved. Using the laws of CSP we show that these basic processes and operators satisfy a number of algebraic equivalences, which enable us to prove equivalence of the different models of the memory system by reasoning entirely at the level of processes, instead of at the lower and more complicated level of events. As a result the proofs of equivalence of the different models are purely algebraic and very simple.
The specification is intended to provide a general framework for any architecture using an interconnection network, such as the on-chip interconnect between macrocells or the networks of processor nodes connected by bit-serial interconnect which are described in [Jon93]. It addresses architecture independent design issues such as access transparency, connectivity, addressing models and serialisability. By structuring it as a hierarchy of models it is hoped that the treatment of these many issues is made as clear and tractable as possible, whilst the proofs of equivalence ensure consistency.
The co-invariant generator: An aid in deriving loop bodies
Authors: Billington David , Dromey R. Geoff 
Published: February 2005

Abstract

Given a loop invariant,
I
, and an assignment,
α
, which decreases the variant, we define a constructive function, cg, called the co-invariant generator, which has the property that
I
Λ cg (
α, I
) ⇒ wp (
α, I
), where wp (
α, I
) is the weakest precondition for
α
to establish I. Several results about the co-invariant generator are proved, important special cases are considered, and a non-trivial example of its use in deriving the body of a loop is given. We also define a function which performs a related constructive action on terms formed from binary operations. The coinvariant generator makes a useful contribution to formalising and automating a key step in program derivation.
Event refinement in state-based concurrent systems
Authors: Sinclair Jane , Woodcock Jim 
Published: February 2005

Abstract
Operations on action systems may be defined corresponding to CSP hiding and renaming. These are of particular use in describing the refinement between action systems in which the granularity of actions is altered. We derive a simplified expression for hiding sets of actions and present sufficient conditions for forwards simulation in which the concrete system uses hiding and renaming. Both of these reduce the complexity of proofs of refinement. We present a case study in specification and refinement using action systems which makes use of the operations and refinement rules previously defined.
Some facile chemistry
Authors: Leth Lone , Thomsen Bent 
Published: February 2005

Abstract
In this paper we use the chemical abstract machine (CHAM) framework [BeB90, BeB92, Bou94] for discussing various semantics for the Facile programming language [GMP89, GMP90, FAR93] and for formalising (parts of) its implementations. We use these formal descriptions to argue (informally) about implementability and cost of implementation in terms of low level machinery needed to implement the given semantics.
We take the Facile language as source for discussion, but the results also apply to several other new languages such as CML [Rep91, BMT92] and Poly/ML [Mat91]. Characteristic for all these languages is that they combine ideas from the λ-calculus and process algebra, such as CCS [Mil80, Mil89], to support high level constructs for programming concurrent, parallel and/or distributed systems.
The full version of this extended summary can be found in [LeT94].
Using units of measurement in formal specifications
Authors: Hayes Ian J. , Mahony Brendan P. 
Published: February 2005

Abstract
In the physical sciences and engineering, units of measurement provide a valuable aid to both the exposition and comprehension of physical systems. In addition, they provide an error checking facility comparable to static type checking commonly found with programming languages. It is argued that units of measurement can provide similar benefits in the specification and design of software and computer systems.
To demonstrate this, we present an extension of the Z specification notation with support for the incorporation of units in specifications and demonstrate the feasibility of static dimensional analysis of the resulting language.
Type inference in stack based languages
Authors: Stoddart Bill , Knaggs Peter J. 
Published: February 2005

Abstract
We consider a language of operations which pass parameters by means of a stack. An algebra over the set of type signatures is introduced, which allows the type signature of a program to be obtained from the type signatures of its constituent operations.
Although the theories apply in principle to any stack based language, they have been evolved with particular regard to the proposed ANSI Standard Forth language, which is currently implemented in a type free manner. We hope this work will stimulate an interest in Forth amongst those applying algebraic techniques in software engineering, and we hope to lay the theoretical foundations for implementing practical type checkers to support Forth.
The formal specification of safety requirements for storing explosives
Authors: Mukherjee Paul , Stavridou Victoria 
Published: February 2005

Abstract
In this paper we consider the current practices involved in the storage of explosive articles and substances. In the spirit of Defence standard 00-55, we formalize the safety requirements of the ACS software which is used to manage certain MOD holdings in the United Kingdom using the specification language VDM. We also prove some properties of these safety requirements and comment on a similar OBJ3 specification.