bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of chemosensitive primary sensory afferents in the central nervous system of the rat
Authors: Jancsó G. , Király Elizabeth
Published: May 2005

By making use of the selective neurotoxic effect of capsaicin on chemosensitive primary sensory neurons, a new experimental approach has been made for the direct morphological demonstration of the distribution of unmyelinated primary sensory afferent fibers to the spinal cord and sensory nuclei of cranial nerves. Chemosensitive primary sensory neurons are known to take part in the transmission of a specific sensory modality, i.e., chemogenic pain.

For the demonstration of axon terminal degeneration, the Fink‐Heimer technique I was used. It was shown that the chemosensitive primary afferents terminated in Rexed's laminae I and II of the spinal cord. In the brainstem degenerating fibers were found to be distributed in the spinal trigeminal nuclei and the solitary system. In the caudal part of the trigeminal nucleus caudalis degeneration argyrophilia was noted both in the subnucleus marginalis and subnucleus gelatinosus, while in the rostral part of the nucleus degeneration was almost exclusively confined to the subnucleus gelatinosus. In addition, a small number of degenerating terminals were found in the nucleus oralis. Heavy terminal degeneration was observed in the nucleus of the solitary tract and the adjoining nucleus commissuralis. Degenerating structures were also found in a small region in the dorsolateral part of the area postrema.

It is concluded that the degenerating afferent fibers terminating in the sensory nuclei of cranial nerves and the spinal cord represent central projections of chemosensitive primary sensory neurons, supplying the skin, mucous membranes, and different visceral areas by the Vth, IXth, and Xth cranial and spinal nerves, respectively.

The participation of chemosensitive neurons in somato‐ and viscerosensory functions, other than chemogenic pain, is also discussed. It is suggested that these chemosensitive primary sensory neurons may, at least in part, be identical with substance P‐containing sensory ganglion cells.
Cortical projections of the lateral geniculate nucleus in the cat
Authors: Geisert E. E.
Published: May 2005

A new application of the retrograde transport method designed to demonstrate neurons that project to two cortical areas has been developed. This method depends on the retrograde axonal transport of two markers, each of which is uniquely detectable by histological methods. In this study, horseradish peroxidase (detectable by the enzymatic reation product only) and tritiated proteins (either enzymatically inactive tritiated horseradish peroxidase or tritiated bovine serium albumin, both of which are detectable by the tritium label only) were used. One of these markers was injected into cortical area 17 and the other was injected into area 18.

In layers A and A1 of the lateral geniculate nucleus, 10% of the cells project to both area 17 and area 18 by axons that branch, 70% of the neurons project to area 17 only, less than 1% of the neurons project to area 18 only, and approximately 20% of the cells are probably interneurons. In the C laminae 50% of the cells project to both areas 17 and 18 by axons that branch, approximately 20% of the neurons project to area 17 only, 10% of the cells project to area 18 only, and about 20% of the neurons are unlabeled. The cells in the medial interlaminar nucleus project to area 17 only, to area 18 only, or to both of these areas by axons that branch.

In addition the retrograde markers were injected into single cortical areas, either area 17, area 18, or area 19. The injections of area 17 and those of area 18 confirmed the results of the double‐label experiments, with 80% of the cells in the A laminae projecting to area 17 and approximately 10% projecting to area 18. Following injections of area 19, labeled neurons were seen in the medial interlaminar nucleus and the C laminae. Therefore, the medial interlaminar nucleus contains cells that project to areas 17, 18, and 19, with some cells projecting to both area 17 and area 18 by axons that branch. In the C laminae the analysis of the projection pattern could be carried further, for it was possible to determine the percentage of labeled neurons in this region. Since 80% of the cells project to areas 17 and 18, and since 60% of the cells of the C laminae were labeled following injections of area 19, many of the cells which project to area 19 must also project to either area 17 or area 18, and some cells must project to all three (areas 17, 18, and 19) by branching axons.
An immunohistochemical characterization of somatostatin‐28 and somatostatin‐281–12 in monkey prefrontal cortex
Authors: Lewis David A. , Campbell Michael J. , Morrison John H.
Published: May 2005

The distribution of the prosomatostatin‐derived peptides (PSDP) somatostatin‐28 (SS‐28) and somatostatin‐281–12 (SS‐281–12) was characterized immunohistochemically in the prefrontal cortical regions of both Old World cynomolgus monkeys (Macaca fascicularis) and New Worldsquirrel monkeys (Saimiri sciureus). Comparison of staining with antisera specific for each peptide revealed that these antigens were segregated within immunoreactive neurons such that SS‐28 was largely confined to theperinuclear region of the cell body whereas SS‐281–12 was primarily found in axons and dendrites.

The laminar pattern of immunoreactive fibers was similar in all areas of the prefrontal cortex. The most dense terminal arborization was in layers I, II, and superficial III. Deep III and IV were traversed by radial fibersthat had little arborization. Layers V and VI contained both radial fibers and a moderately dense terminal plexus. Labeled fibers were less numerous in the white matter. There were marked regional differences in fiber density. Areas 12 and 24 had the greatest density of immunoreactive fibers, areas 9, 11, and 25 were of intermediate density, and areas 10 and 46 were the least dense.

Most of the immunoreactive cells appeared to be multipolar or bitufted. They were found throughout all cortical layers and the white matter. The largest number were located in layers II, superficial III, and deep V and VI. There were also marked regional differences in cell body density, which paralleled the regional differences in fiber density. Area 24 (anterior cingulate) had the greatest density of immunoreactive cell bodies (148 ± 14/mm2), area 9 was of intermediate density (109 ± 13/mm2), and area 46 was the least dense (83 ± 12/mm2).

Our findings indicate that PSDP compose a complex and extensive cortical system that is largely or totally intrinsic. The substantial regional heterogeneity in density exhibited by PSDP‐containing neurons has not previously been reported for an intrinsic cortical system. The laminar and regionalinnervation patterns of these fibers and cell bodies suggest that the PSDP cortical system may play an important role in the polymodal information processing that occurs in association regions of prefrontal cortex.
Quantitative comparison of retinal synapses in the dorsal and ventral (parvicellular) C laminae of the cat dorsal lateral geniculate nucleus
Authors: Mize R. Ranney , Spencer Robert F. , Horner Linda H.
Published: May 2005

Three physiological classes of retinal ganglion cell project to the cat dorsal lateral geniculate nucleus (DLGN). The dorsal laminae A, A1, and magnocellular C receive X and Y retinal input, whereas the ventral parvicellular laminae C1 and C2 receive predominantly W input. We have compared quantitatively the retinal synaptic terminals of the dorsal and ventral laminae to determine whether there are morphological differences in the terminals that correspond to their different response properties Anterogradely labeled retinal synaptic terminals in all laminae contained pale mitochondria and large, round synaptic vesicles. However, rerminals with pale mitochondria varied in size and synaptic organization in different laminae. The terminals in the A laminae were on average, quite large and made numerous contacts with conventional dendritic profiles and with profiles that themselves contained synaptic vesicles (F2 profiles). The terminals in lamina C that contained pale mitochondria had a smaller overall mean area. Terminals with pale mitochondria in C1 and C2 were almost all small and synapsed with F2 profiles less frequently than did terminals in the A laminae or in lamina C. These results provide quantitative evidence that visual areas receiving W‐type retinal input contain smaller retinal terminals and have a different synaptic organization from that of laminae receiving X and Y input.
Rabbit cingulate cortex: Cytoarchitecture, physiological border with visual cortex, and afferent cortical connections of visual, motor, postsubicular, and intracingulate origin
Authors: Vogt Brent A. , Sikes Robert W. , Swadlow Harvey A. , Weyand Theodore G.
Published: May 2005

The connections of cingulate cortex with visual, motor, and parahippocampal cortices in the rabbit brain are evaluated by using a modified Brodmann cytoarchitectural scheme, electrophysiological mapping techniques, and the pathway tracers horseradish peroxidase (HRP) and tritiated amino acids. Rabbit cingulate cortex can be divided into areas 25, 24, and 29. Area 29 isof particular interest because area 29d has a lateral extension with a granular layer IV, area 29b has a caudal extension in which the connections differ from anterior area 29b, and there is a prominent area 29e. delineation of the lateral border of area 29d with area 17 closely approximates the medial edge of the visual field representation in area 17 as determined electrophysiologically.

The main interconnections between visual and cingulate cortices occur between cingulate areas 24b and 29d and visual areas 18 and medial parts of area 17. Projections between areas 29d and 18 are organized in a loose topographic fashion with rostral parts of each and caudal parts of each being reciprocally connected. Neurons mainly in superficial layer II‐III of areas 17 and 18 project to layer I of area 29d, while the reciprocal projection originates from neurons in layer V of area 29d and project mainly to layer Iof areas 17 and 18.

The medial portion of motor area 8 projects to areas 18 and 29d and hasa smaller projection to area 17.

Postsubicular area 48 is reciprocally connected with area 29d, and it also projects to areas 29b and c. The subiculum projects to areas 29a and 29c but only to the anterior two‐thirds of area 29b not the posterior one‐third.

Rostral area 29d receives the most extensive intrinsic cingulate projections including those from all major cytoarchitectural divisions. Interconnections between areas 29d and 29b appear to be topographically organized inthe rostrocaudal plane. Area 29c projects more heavily to area 29b than vice versa. Finally area 29d projects mainly to area 24b in anterior cingulatecortex.

In conclusion, rostral area 29d has extensive connections with visual areas 17 and 18, motor area 8, and all subdivisions of cingulate cortex. In light of these connections, it may play a pivotal role in associative functions of the rabbit cerebral cortex including visuomotor integration.
The topographical organization of the vagal motor column in the elasmobranch fish, Scyliorhinus canicula L.
Authors: Withington‐Wray D. J. , Roberts B. L. , Taylor E. W.
Published: May 2005

The location within the brainstem of vagal preganglionic motoneurons has been determined in the dogfish Scyliorhinus canicula L. by means of the retrograde transport of horseradish peroxidase and cobalt applied to the vagus nerve and its component branches. Labelled vagal motoneurones were located in the ipsilateral caudal rhombencephalon from 2.1 mm caudal to 2.72 mm rostral to obex.

The motoneurons of the vagal motor column are arranged as four distinct groups. Caudal to obex the column contains dorsomedial and ventromedial divisions, whilst rostrally it consists of a single rostromedial division and a short lateral division. The cells in the ventromedial division are approximately twice the size (mean area 1,094 μm2) of the other vagal neurons.

The dorsomedial division contains neurons that supply the heart and viscera; the ventromedial division supplies the viscera. The heart is also innervated by the neurons of the lateral division and the visceral nerve also receives axons from the rostromedial division. All neurons supplying axons to the gill arches are located in the rostromedial division.

There is a sequential topographical representation of the vagus nerve in the vagal motor column. Neurons supplying the gastrointestinal tract are located caudally; those supplying the cardiac nerves lie in the midportion of the column, and the proximal supply to the gills is given by the most rostral neurons. There is some overlap between the pools of neurons supplyingadjacent branches of the vagus.
The development and migration of large multipolar neurons into the cochlear nucleus of the North American opossum
Authors: Willard F. H. , Martin G. F.
Published: May 2005

We have studied the maturation of the inferior colliculus and cochlear nuclei of the North American opossum with particular emphasis on the large multipolar neurons of the cochlear nucleus. These neurons include the principal and giant cells of the dorsal cochlear nucleus (DCN) and the large neurons of the ventral cochlear nucleus (VCN), all of which can be labelled byhorseradish peroxidase (HRP) injections into the contralateral inferior colliculus (IC). The size of these neurons, their characteristic Nissl patterns, and their labelling density after injections into the IC render them distinguishable from other neurons in this nuclei, even in young animals.

In Nissl‐stained sections of newborn opossums, a band of horizontally oriented neurons can be identified dorsomedial to the vestibular nerve root. This band extends from an apparent cytogenetic zone close to the sulcus limitans, to, but not within, the presumptive cochlear nucleus. Between birth and estimated postnatal day 22 (EPND 22) the band shifts laterally, eventually becoming incorporated into the cochlear nucleus. Many neurons in this band have perinuclear caps of Nissl substance similar to those present in the principal cells of the adult DCN.

Injections of HRP into the IC as early as EPND 5 (17 days after conception) labelled neurons in the band referred to above but not in the presumptive cochlear nucleus. By EPND 15, labelled cells were clustered mainly within the nucleus proper. Most of these cells were located in the DCN, but a few were scattered in the dorsocentral VCN. Consistent labelling of small neurons in VCN was not obtained until sometime later. From EPND 15 to EPND 20 most of the labelled cells in DCN reoriented in the vertical plane, aligned in layer II, and differentiated into principal neurons. Some, however, remained deep to layer II and differentiated into giant neurons. The heavily labelled cells in VCN differentiated into large neurons.

Our results suggest that the large multipolar neurons of the nucleus are generated in a cytogenetic zone medial to the rhombic lip and that they subsequently migrate laterally, in a band, to reach their adult locations inthe nucleus. It is during this migratory stage that their axons reach the inferior colliculus.
Light and electron microscopic study of an avian pretectal nucleus, the lentiform nucleus of the mesencephalon, magnocellular division
Authors: Gottlieb Michael D. , McKenna Olivia C.
Published: May 2005

Using several light microscopic methods we have identified the lentiform nucleus of the mesencephalon, magnocellular division, by its position in the pretectum, its cellular composition, and its complement of retinal afferents and have distinguished it from neighboring structures. At the light microscopic level large neurons (approximately 30 × 21 μm) and small neurons (approximately 13 × 9 μm), which are more numerous, are seen interspersed among myelinated axons. The large neurons are generally ovoid and contain an eccentrically located nucleus and large clumps of Nisslstained material. In the electron microscope the most notable feature of these neurons is the presence of ribosome rosettes and many parallel arrays of rough endoplasmic reticulum (RER). On the basis of cytological and ultrastructural features, we conclude that only one class of large neuron is present. Although in the light microscope the small neurons appear to be similar, at the ultrastructural level three neuron types have been distinguished:(1) ovoid shape with cytoplasm densely packed with organelles especially RER, (2) round shape with very little cytoplasm with few organelles, and (3) triangular shape with a pale cytoplasmic matrix with some RER. Subsurface membrane configurations are often seen in the somata of all neuron types. Inaddition, axon terminals, some containing flat vesicles, and other less frequent ones containing round vesicles are seen terminating on the somata of all neuronal cell types. In the neuropil, three types of presynaptic profiles can be identified. Two of these profiles are axodendritic and the third is dendrodendritic. The type R profile, which is often as large as 4 μm2, is the most numerous, contains large round synaptic vesicles, and is often seen synapsing on several dendritic profiles. The type F profilecontains flat vesicles and a relatively dense cytoplasm, and is smaller in area than type R. The third profile, which contains small clusters of pleiomorphic vesicles and apparently is dendritic, forms synapses with dendriticprofiles. We propose that the type R axon terminals originate mostly from the retina and the type F mostly from the visual telencephalon.
Novel use of the BD FACS™ SPA to automate custom monoclonal antibody panel preparations for immunophenotyping
Authors: Kelliher Abigail S. , Parent David W. , Anderson David C. , Dorn Michelle E. , Hahn Jessica L. , Eapen Sara , Preffer Frederic I.
Published: May 2005

Background

The effective and accurate diagnosis of hematologic malignancies relies on flow cytometric immunophenotyping. Selected combinations of monoclonal antibodies (mAbs) arranged in multicolor panels allow for the accurate definition of normal and abnormal hematologic cell populations. The most time‐consuming and crucial step in the staining process involves dispensing combinations of multiple mAbs into their appropriate staining tubes. This step is prone to error, requires concentration and accuracy, and is dependent on technologist experience.

The Becton Dickinson BioScience (BD) FACS™ Sample Prep Assistant (SPA) is touted as a breakthrough in automated in vitro diagnostic sample preparation. The SPA is designed to automate BD MultiTEST™ and BD TriTest lyse/no‐wash assays. However, because most cases in our laboratory require tedious application of unique four‐color mAb cocktails for leukemia and lymphoma testing, we wondered whether the SPA would be helpful in accurately dispensing these mixtures.

Methods

The mAb panels were prepared by the SPA in two separate timed runs and on separate days. Eleven specimens (nine from patients and two from normal volunteers) were split and stained with four‐color cocktails created by the SPA or manually. The percentage of positive (%P) cells and mean fluorescent intensity for each mAb pair were determined. These values were plotted against each other and correlation values were calculated. To quantitate timesaving in the laboratory, two technologists prepared individually the same mAb panels and were timed.

Results

The correlation between the two methods was high; r2 was 0.988 for 158 %P antigen pairs; no bias between the manual and robotic methods was detected with the Wilcoxon rank test. Bland‐Altman analysis indicated no obvious relation between the difference and the mean of %P cells, suggesting that the SPA successfully dispensed antibodies for leukemia/lymphoma panels. The two methods may be interchangeable, although the limited sample size prohibits this conclusion from Bland‐Altman statistics alone. In addition, one possible error was detected in the SPA‐prepared panels. The SPA averaged 65 min/run, the experienced technologist 12.95 min/run, and the inexperienced technologist 54.9 min/run.

Conclusions

SPA dispensing time was twice the average manual dispensing time; however, SPA use was completely automated and freed the technologist to perform other tasks. SPA use permitted preemptive preparation of mAb panels and thus streamlined processing; however, the cost of the assay and the amount of reagent waste increased. It is certain that software modifications by BD could decrease the SPA reagent dispense time and decrease the cost associated with reagent waste when the SPA is used in this novel fashion. © 2005 Wiley‐Liss, Inc.
Ultrastructural analysis of the smooth‐to‐striated transition zone in the developing mouse esophagus: Emphasis on apoptosis of smooth and origin and differentiation of striated muscle cells
Authors: Wörl Jürgen , Neuhuber Winfried L.
Published: May 2005

The exact mechanism of smooth‐to‐striated muscle conversion in the mouse esophagus is controversial. Smooth‐to‐striated muscle cell transdifferentiation vs. distinct differentiation pathways for both muscle types were proposed. Main arguments for transdifferentiation were the failure to detect apoptotic smooth and the unknown origin of striated muscle cells during esophageal myogenesis. To reinvestigate this issue, we analyzed esophagi of 4‐day‐old mice by electron microscopy and a fine‐grained sampling strategy considering that, in perinatal esophagus, the replacement of smooth by striated muscle progresses craniocaudally, while striated myogenesis advances caudocranially. We found numerous (1) apoptotic smooth muscle cells located mainly in a transition zone, where smooth intermingled with developing striated muscle cells, and (2) mesenchymal cells in the smooth muscle portion below the transition zone, which appeared to give rise to striated muscle fibers. Taken together, these results provide further evidence for distinct differentiation pathways of both muscle types during esophagus development. Developmental Dynamics 233:964–982, 2005. © 2005 Wiley‐Liss, Inc.
Pink‐eyed dilution alleles affect negative surface charges of mouse spermatozoa
Authors: Hash D. Coleman , Wolfe H. Glenn
Published: May 2005

Abnormal spermiogenesis in sterile pink‐eyed dilution mutants results in spermatozoa with bizarre sperm heads. The spermatozoa of normal mice bind colloidal iron hydroxide (CIH) along the length of the tail, yet the spermatozoa of pink‐eyed sterile mice show a great reduction in ability to bind CIH. This implies a loss of negative surface charges. The group(s) responsible for the charges are sensitive to methylation but resistant to neuraminidase treatment, even after deacetylation with alkaline treatment. The membrane components containing the negatively charged groups may be neuraminidase‐resistant forms of gangliosides.
Maternal effect for genes encoding 6‐phosphogluconate dehydrogenase and glucose‐6‐phosphate dehydrogenase in Drosophila melanogaster
Authors: Gerasimova T. I. , Smirnova S. G.
Published: May 2005

We studied the maternal effect for two enzymes of the pentose cycle, 6‐phosphogluconate dehydrogenase (6PGD) and glucose‐6‐phosphate dehydrogenase (G6PD), using a genetic system based on the interaction of Pgd− and Zw− alleles, which inactivate 6PGD and G6PD, respectively. The presence and formation of the enzymes was investigated in those individuals that had not received the corresponding genes from the mother. We revealed maternal forms of the enzymes, detectable up to the pupal stage. The activities of “maternal” 6PGD and G6PD per individual increased 20‐fold to 30‐fold from the egg stage to the 3rd larval instar even in the absence of normal Pgd and Zw genes. Immunologic studies have shown that the increase in 6PGD activity is due to an accumulation of the maternal form of the enzyme molecules. We revealed a hybrid isozyme resulting from an aggregation of the subunits of isozymes controlled by the genes of the mother and embryo itself. These results indicate that the maternal effect in the case of 6PGD is due to a long‐lived stable mRNA transmitted with the egg cytoplasm and translated during the development of Drosophila melanogaster.
Biochemical and genetic analysis of a mutant with altered alkaline phosphatase activity in Dictyostelium discoideum
Authors: MacLeod Carol L. , Loomis William F.
Published: May 2005

Alkaline phosphatase is one of several enzymes that accumulate in a temporally regulated sequence during the development of Dictyostelium discoideum. These enzymes can be used to monitor specific gene expression; moreover, isolation and analysis of mutations in the structural gene(s) can serve to indicate some of the essential steps in programmed synthesis and morphogenesis. A mutation (alpA) which affects the activity and substrate affinity of alkaline phosphatase was isolated in D discoideum using a procedure for screening large numbers of clones. Alkaline phosphatase activity at all stages of vegetative growth and development was altered by the mutation. Several physical properties of the enzyme from growing cells and developed cells were compared and found to be indistinguishable. It is likely that a single enzyme is responsible for the majority of alkaline phosphatase activity in growth and development. The mutation is coexpressed in diploids heterozygous for alpA and maps to linkage group III. One of the haploid segregants isolated from these diploids carries convenient markers on each of the six defined linkage groups and can be used for linkage analysis of other genetic loci.
Induction of multiple flagella in Naegleria: Requirements for RNA and protein synthesis
Authors: Walsh Charles , Mar Janet , Ugen Kenneth
Published: May 2005

The induction of multiple flagella by a heat shock was used to examine the role of RNA and protein synthesis in the regulation of the number of flagella produced during the differentiation of the amebo‐flagellate Naegleria gruberi. Control cells differentiating at 25.0°C produce an average of 2.1 flagella per flagellate (f/F), whereas cells exposed to 38.2°C from 35 minutes until 72 minutes after initiation produce an average of approximately 5 f/F. Heat shock was found to prevent completion of the RNA synthesis essential for flagellum formation, even though both RNA and protein synthesis continued at 38.2°C. A delay of two minutes for every one minute of heat shock was seen in both the formation of flagella (T50) and the completion of essential RNA synthesis for heat shocks of one to ten minutes applied beginning 35 minutes after initiation. Times at 38.2°C of ten minutes to 45 minutes produced a delay of approximately 0.6 minutes for each minute of heat shock, whereas shocks longer than 47 minutes prevented flagellum formation. The times from completion of RNA synthesis until completion of protein synthesis or flagella formation were found to be approximately 15 minutes and approximately 32 minutes, respectively. This was true in control cells as well as in cells heat shocked for up to 45 minutes. The fact that heat shock delayed completion of RNA synthesis without affecting the time for completion of protein synthesis or flagella formation suggests that heat shock acts at some step related to the completion of transcription. Short heat shocks, 30 seconds to five minutes, were observed to prevent flagellum formation in cells that had completed RNA synthesis if additional RNA synthesis was inhibited. In contrast, short heat shocks had little effect on cells that had completed protein synthesis, even if additional protein synthesis was inhibited. Two alternative hypotheses for the mechanism of heat shock delay of transcription are discussed. One hypothesis involves a direct effect of high temperature on transcription, and the other postulates a temperature‐sensitive protein necessary for flagellum formation.
Rates of synthesis and turnover of 5′ cap structures of hnRNA and mRNA and their changes during sea urchin development
Authors: Nemer Martin , Ginzburg Irith , Surrey Saul , Litwin Samuel
Published: May 2005

The relationship between heterogeneous nuclear RNA (hnRNA) and messenger RNA (mRNA) synthesis has been studied as a function of the development of the sea urchin embryo through the use of methyl incorporation. Several parameters in the metabolism of capped hnRNA and mRNA of early blastula and late gastrula stages have been investigated by measuring the kinetics of transfer of methyl groups from S‐adenosylmethionine to the 5′ cap structures in nuclear and cytoplasmic RNA:

The rate constants for the decay of hnRNA caps and the synthesis of mRNA caps are equal to within experimental error. This equality indicates a flux of precursor hnRNA caps to mRNA caps with a very high degree of conservation of the hnRNA caps. This conservation holds for each embryonic stage.

From literature data on the labeling kinetics of GTP and mRNA, we have calculated the decay constant of a putative mRNA precursor component of hnRNA. The value of this constant is very close to that for the decay constant of hnRNA caps. Hence, all hnRNA caps and some portion of their associated hnRNA sequences behave kinetically as the pre‐mRNA fraction. This kinetically ascribed pre‐mRNA comprises approximately 30% of the hnRNA mass.

The part of the hnRNA which does not serve as precursor to mRNA turns over at least twice as rapidly as the pre‐mRNA fraction.

During development from early blastula to late gastrula, the rate of hnRNA cap synthesis drops from 2 × 103 molecules/min/cell to half of this value. This decline is parallel to the decline in total hnRNA synthesis and thereby confirms the constant degree of capping of hnRNA, as previously reported. We infer that the pre‐mRNA fraction of hnRNA remains nearly constant during this developmental period.
Specific protection from phenocopy induction by heat shock
Authors: Mitchell Herschel K. , Moller Galina , Petersen Nancy S. , Lipps‐Sarmiento Loveriza
Published: May 2005

Mild heat treatments applied to whole animals or cell cultures of Drosophila prior to lethal heat shocks result in increased survival and protection against phenocopy induction. The optimal condition for the preliminary mild heat treatment is that which induces the synthesis of heat‐shock proteins but does not turn off the protein synthesis that is in progress. Recovery of protein synthesis but not RNA synthesis following a drastic heat shock is much enhanced by the pretreatments. The results suggest that the protection for survival and against phenocopy induction is due to storage of messenger RNA.
Correlation of phenotypes of the apterous mutation in Drosophila melanogaster
Authors: Wilson Thomas G.
Published: May 2005

The apterous (ap) mutant in Drosophila melanogaster exhibits phenotypes of wing deficiency, precocious adult death, and nonvitellogenic oocyte development. The latter phenotype previously has been shown to result from juvenile hormone (JH) deficiency in the adult stage. To explore the relationship between the hormone deficiency and the other phenotypes, the expression of each phenotype was measured in five alleles of ap (including a new, chemically‐induced allele, ap77f) as wing length, survival five days after eclosion, and initiation and progress of vitellogenic oocyte development. No correlation could be found between severity of wing phenotype and that of precocious adult death or nonvitellogenesis. However, the latter phenotypes were correlated in both ap homozygotes and allelic heterozygotes, since adults that survive have wild‐type vitellogenesis, and those fated for precocious death fail to develop vitellogenic oocytes. These results indicate that no relationship exists between wing and JH deficiencies, but that precocious adult death is related to hormone deficiency — probably through pleiotropy, rather than through causality.
Genetic rescue of lethal genotypes in the mouse
Authors: Gluecksohn‐Waelsch Salome , Teicher Luz S. , Pick Leslie , Cori Carl F.
Published: May 2005

Deletions of gene sequences in chromosome 7 of the mouse are known to interfere with biochemical and cellular development differentiation with lethal effects in homozygotes. The presence of the corresponding wild‐type alleles in Cattanach's translocation (chromosomes 7 to X) is able to “rescue” potentially lethal females if they are made heterozygous for the translocation‐carrying X chromosome. This holds true for those chromosome 7 deletions with perinatally lethal effects, whereas “rescue” is not readily accomplished with the deletions that cause early embryonic lethality. Females homozygous for the relevant deletion sequences and heterozygous for the translocation‐carrying X chromosome are mosaics of two cell types: those in which the wild‐type alleles included in the translocated piece complement the depleted sequences, resulting in a normal cellular phenotype, and those with the ordinary X chromosome expressing the lethal phenotype. The developmental interactions between the two cell types and their role in the mechanisms responsible for survival of females homozygous for lethal deletions are discussed. The failure of “rescue” of embryonic lethals reflects as yet unknown temporal and functional aspects of X‐inactivation early embryogenesis.
A β‐glucosidase gene of Dictyostelium discoideum
Authors: Loomis William F.
Published: May 2005

Seven mutations affecting β‐glucosidase activity in Dictyostelium discoideum were found to be non‐complementing, recessive to the wild‐type allele, and to occur in the gene locus, gluA. This gene, which is likely to be the structural gene for β‐glucosidase, since a mutation in it gives rise to thermolabile activity and other mutations in it result in no measurable activity, was mapped to linkage group VI. The expression of the β‐glucosidase gene is regulated such that the enzyme is synthesized during the growth phase and during culmination, but not during the first 18 hours following the initiation of development. If expression of the structural gene required the function of a positive regulatory protein coded for by a gene as mutable as the gluA gene, there was greater than 99% chance one of the mutations of this series would have affected the regulatory locus. The absence of a second complementing locus for β‐glucosidase suggests that this enzyme is regulated by other means.
The chorion defect of the ocelliless mutation caused by abnormal follicle cell function
Authors: Underwood E. M. , Mahowald A. P.
Published: May 2005

Homozygous Drosophila females bearing the ocelliless mutation are sterile and produce oocytes with abnormal chorions. It has been possible to determine in which tissues these defects reside by generating ovarian chimeras. Pole cells from ocelliless female embryos can give rise to functional oocytes surrounded by normal chorions when placed in a wild‐type environment. Conversely, when wild‐type pole cells are placed in homozygous ocelliless females, the oocytes that form from them have abnormal chorions and never give rise to progeny. Thus the chorion defect and sterility of the ocelliless mutation are not germ‐line autonomous. Homozygous ocelliless ovaries will attach to the uterus when placed in a wild‐type third instar larva, but few eggs are ever laid, and the chorions of stage 14 oocytes remain ocelliless in morphology. Wild‐type ovaries continue to produce oocytes with normal chorion morphology when placed into ocelliless hosts, indicating that the ocelliless chorion defect is ovary autonomous. Thus the chorion defect of the ocelliless mutation resides in the ovarian somatic tissue, presumably the follicle cells.
Evaluation of a catalase inhibitor in the developmental regulation of maize catalase
Authors: Tsaftaris Athanasios S. , Sorenson John C.
Published: May 2005

A protein which has been shown to inhibit catalase in vitro appears to vary inversely with catalase activity in the maize scutellum during early sporophytic development when assayed using a catalase inhibition assay. This result suggested that the inhibitor protein may play a direct role in regulating catalase activity during this time period.

Four experimental approaches were used to evaluate this putative regulatory role, including immunological quantitation of individual catalase isozymes during germination using rocket immunoelectrophoresis, perturbation of normal catalase expression with hydrogen peroxide or allylisopropylacetamide (AIA), examination of a mutant line with an altered catalase developmental program, and direct radioimmunoassay of the inhibitor protein during germination. The results of these experiments indicate that the quantitative changes in catalase activity during development are not mainly due to changes in the expression of the catalase inhibitor. Other possible roles of this protein in catalase regulation are discussed.
The developmental genetics of pigment mutants in the Mexican axolotl
Authors: Frost Sally K. , Malacinski George M.
Published: May 2005

The Mexican axolotl (Ambystoma mexicanum) provides a well‐defined set of color genes which are useful for various types of analyses. These include the a (albino), m (melanoid), ax (axanthic), and d (white) genes. In addition, various combinations of these genes and a number of as yet undescribed mutants also exist. Three of these mutants (a, ax, and m) have defects associated with specific neural‐crest‐derived pigment cell types. The fourth mutant (d) appears to provide an unsuitable environment for the migration and maintenance of pigment cells. In one case (m), detailed information concerning the specific nature of the genetic defect is available.

The goal of this article is to demonstrate ways in which the existing information on the axolotl color genes can best be utilized in terms of understanding not only the mutant phenotypes, but basic concepts in the cell and developmental biology of pigmentation as well. Thus, an attempt has been made to sort through the genetic and biochemical data relevant to these mutants in order to stimulate renewed interest in a more detailed pursuit of such studies.
Role of pupal‐esterase in the regulation of the hormonal status in two Drosophila virilis stocks differing in response to high temperature
Authors: Rauschenbach I. Y. , Lukashina N. S. , Korochkin L. I.
Published: May 2005

Drosophila virilis stocks differing in reaction to high temperature (32°C) were studied. The sizes of the larval salivary glands, ring gland, and imaginal discs of the heat‐sensitive stock 147, whose pupal (p) esterase was activated at 32°C, were found to be significantly smaller at high temperature than at 25°C. In larvae of the heat‐resistant stock 101, whose p‐esterase was inactivated at 32°C, the salivary glands and imaginal discs were larger under conditions of high temperature than those of the control larvae. Treatment of stock 147 larvae with ecdysone at 32°C did not affect p‐esterase activity and was 100% lethal. By contrast, the juvenile hormone activated p‐esterase under these conditions and normalized the development of stock 147 larvae. A scheme is suggested for the role of p‐esterase in the regulation of the hormonal status of D. virilis under high temperature conditions.
Control of in vitro growth of viviparous embryo mutants of maize by abscisic acid
Authors: Robichaud C. S. , Wong J. , Sussex I. M.
Published: May 2005

The plant hormone abscisic acid (ABA) is believed to play a role in the onset of developmental arrest in seeds. Embryos of the viviparous mutants of Zea mays do not undergo arrest but germinate directly on the ear. This study investigates the possibility that the mutants vp1, vp5, vp7, vp8, and vp9 are defective in some aspect of ABA action. Mutant and wild type embryos were removed from developing seeds at 18, 21, and 24 days after pollination and cultured aseptically on media containing a range of ABA concentrations. Seedlings were harvested after seven days when lengths and fresh and dry weights were recorded. The results indicate that these five viviparous mutants differ in their response to ABA. Two mutants, vp5 and vp8, exhibit the same sensitivity to growth inhibition by ABA as wild type. The remaining three mutants, however, manifest a range of decreased sensitivities with vp1 being the least sensitive, followed by vp7 and vp9.
Heat shock induced proteins in plant cells
Authors: Barnett Thomas , Altschuler Mitchell , McDaniel Carl N. , Mascarenhas Joseph P.
Published: May 2005

Tobacco (Nicotiana tabacum) and soybean (Glycine max) tissue culture cells were exposed to a heat shock and protein synthesis studied by SDS‐polyacrylamide gel electrophoresis after labeling with radioactive amino acids. A new pattern of protein synthesis is observed in heat‐shocked cells compared to that in control cells. About 12 protein bands, some newly appearing, others synthesized in greatly increased quantities in heat‐shock cells, are seen. Several of the heat‐shock proteins (HSPs) in both tobacco and soybean are similar in size. One of the HSPs in soybean (76K) shares peptide homology with its presumptive 25°C counterpart, indicating that the synthesis of at least some HSPs may not be due to activation of new genes. The optimum temperature for maximal induction of most HSPs is 39–40°C. Total protein synthesis decreases as heat‐shock temperature is increased and is barely detectable at 45°C. The heat‐shock response is maintained for a relatively short time in tobacco cells. After 3 hr at 39°C, a decrease is seen in the synthesis of the HSPs, and after 4 hr practically no HSPs are synthesized. After exposure to 39°C for 1 hr, followed by a return of tobacco cells to 26°C, recovery to the control pattern of synthesis requires greater than 6 hours. These results indicate that cells of flowering plants exhibit a heat‐shock response similar to that observed in animal cells.
Restriction of PGK‐B to spermatogenic cells: Evidence from experimentally cryptorchid mice
Authors: Rudolph Natalie S. , VandeBerg John L.
Published: May 2005

The hypothesis that PGK‐B, like LDH‐C4, is restricted to spermatogenic cells was explored by examining isozyme patterns in testes from mice depleted of germinal cells by surgical cryptorchism. In experimentally cryptorchized C57BL/10Sn males, decline in PGK‐B activity paralleled decline in LDH‐C4 activity and was correlated with degeneration of spermatocytes, spermatids, and spermatozoa. Trace amounts of these sperm isozymes found in cryptorchid testes after the depletion of maturing germ cells probably came from degenerated spermatids and spermatocytes and not from somatic testicular cells.
Recombinant DNA analysis indicates that the multiple chromosomes of maize mitochondria contain different sequences
Authors: Spruill W. M. , Levings C. S. , Sederoff R. R.
Published: May 2005

Twenty‐eight Bam H 1 restriction fragments were isolated from normal mitochondrial DNA of maize by recombinant DNA techniques to investigate the organization of the mitochondrial genome. Each cloned fragment was tested by molecular hybridization against a Bam digest of total mitochondrial DNA. Using Southern transfers, we identified the normal fragment of origin for d each clone. Twenty‐three of the tested clones hybridized only to the fragment from which the clone was derived. In five cases, labeling of an additional band indicated some sequence repetition in the mitochondrial genome. Four clones from normal mitochondrial DNA were found which share sequences with the plasmid‐like DNAs, S‐1 and S‐2, found in S male sterile cytoplasm. The total sequence complexity of the clones tested is 121×106 d (daltons), which approximates two thirds of the total mitochondrial genome (estimated at 183×106 d).

Most fragments do not share homology with other fragments, and the total length of unique fragments exceeds that of the largest circular molecules observed. Therefore, the different size classes of circular molecules most likely represent genetically discrete chromosomes in a complex organelle genome. The variable abundance of different mitochondrial chromosomes is of special interest because it represents an unusual mechanism for the control of gene expression by regulation of gene copy number. This mechanism may play an important role in metabolism or biogenesis of mitochondria in the development of higher plants.
The expression of β‐galactosidase during preimplantation mouse embryogenesis
Authors: Esworthy Steve , Chapman Verne M.
Published: May 2005

Lysosomal acid hydrolase expression during preimplantation mouse embryogenesis has proved useful in estimating when mRNA transcription commences during this period. Previous work from this laboratory has shown that α‐galactosidase and β‐glucuronidase undergo 50‐ to 100‐fold increases in activity between the two‐cell stage and the blastocyst stage [1, 2]. Here we show that β‐galactosidase activity levels undergo a similar change. We also demonstrate that mouse strains with the Bgl‐sh allele produce cleavage stage embryos with 2–4‐fold higher activity levels than strains with the Bgl‐sd allele. Bgl has been shown to control β‐galactosidase levels in adult mouse tissues [3]. Unfertilized egg β‐galactosidase levels are also regulated by Bgl, but loci distant from Bgl modify egg expression. The distant sites are not observed to act during cleavage. Hybrid embryos (Bgl‐sd/h) show intermediate activity levels to the parental types. The timing of the deviation of hybrid embryo β‐galactosidase activity levels from maternal‐type activity levels is used to estimate when transcription of genes governing β‐galactosidase expression occurs.
Genetic analysis of mating type differentiation in Paramecium tetraurelia. III. A mutation restricted to mating type E and affecting the determination of mating type
Authors: Brygoo Yves , Keller A. M.
Published: May 2005

In P. tetraurelia each cell is determined to express only one of the two complementary mating types, O and E. This determination is under cytoplasmic control and seems to be achieved only by the commitment or noncommitment to the expression of mating type E. All the previously known mutations affecting the differentiation of mating type prevent the expression of the E mating type (O‐restricted mutations) without affecting the determination process. An E‐restricted mutation was obtained: mtFE. Its phenotypic properties indicate that the mutation affects the determination process itself. When an O cell becomes mtFE/mtFE it acquires the E mating type and an E‐determining cytoplasm. We propose that this constitutive determination for the E mating type is due to the inefficiency of a factor which is normally active in an O cell. This factor would act like a repressor and stabilize the E functions under an inactive state.
A mutation with pleiotropic effects on macronuclearly differentiated functions in Paramecium tetraurelia
Authors: Brygoo Yves , Keller A. M.
Published: May 2005

The mtFE mutation isolated in Paramecium tetraurelia affects mating type differentiation, trichocyst excretion, and viability. Its effect on mating type has already been shown to correspond to a restriction to the E mating type interpreted by an inefficiency of nuclear O‐determining factors. In this paper we study the other two phenotypic characteristics whose hereditary transmission displays two unusual features. (1) In crosses between a wild‐type strain and the mutant strain, the mutant characteristics do not reappear in F2 in the wild‐type cytoplasmic lineage but only in F3 after the homozygous clones have undergone an additional nuclear reorganization. (2) Some F2 wild‐type clones, in the mutant cytoplasmic lineage, retain some of the phenotypic characteristics of the mutant. We propose that the mtF gene product plays a role in the control of several macronuclearly differentiated functions.