bluuebunny/crossref_metadata_2025 huggingface dataset:
Aminopeptidase a from Rhynchosciara americana (Diptera) larval midguts: Properties and midgut distribution
Authors: Klinkowstrom Adriana M. , Terra Walter R. , Ferreira Clélia
Published: February 2005

L‐aspartic acid α‐(β‐naphthylamide) (AspβNA) hydrolase activity is restricted mostly to the midgut caeca of Rhynchosciara americana larvae. The membrane‐bound activity is solubilized in detergent and, after electrophoretic separation, proved to be identical to leucine p‐nitroanilide (LpNA) hydrolases previously described. Differential centrifugation of midgut caeca homogenates, followed by assays of enzyme markers and aminopeptidase, suggests that the soluble AspβNA hydrolase is associated with the cell glycocalyx. Soluble aminopeptidases from R. americana midgut caeca are resolved into three fractions by gel electrophoresis. The slow migrating fraction hydrolyzes AspβNA well and displays a low activity on LpNA and proline β‐naphthylamide (ProβNA). Thus, this enzyme is an aminopeptidase A (EC 3.4.11.7). It has a pH optimum of 7.5, Mr 117,000 (gel filtration), and is competitively inhibited by aspartate hydroxamate (Ki 0.1 mM). Nevertheless, this enzyme, in contrast to the vertebrate enzyme, is not activated by calcium ions. The aminopeptidase A seems to have a charge variant that displays an intermediate migration and is not resolved from an aminopeptidase N (enzyme very active on LpNA). These two activities are not resolved by either gel filtration or ion‐exchange chromatography. The aminopeptidases N with intermediate and high migration, previously reported to be charge variants, were shown in this paper to differ in substrate specificities and in the strength with which they associate to the cell glycocalyx. © 1994 Wiley‐Liss, Inc.
Effect of KK‐42 on growth, development, molting, and metamorphosis of the european corn borer, Ostrinia nubilalis (Hübner)
Authors: Gelman Dale B. , Bell Robert A. , DeMilo Albert B. , Kochansky Jan P.
Published: February 2005

KK‐42 (1‐benzyl‐5‐[(E)‐2,6‐dimethyl‐1,5‐heptadienyl]imidazole), administered by feeding, delayed the growth and development of nondiapause‐bound and diapause‐bound Ostrinia nubilalis larvae and increased the length of the instar. At doses of 80–240 ppm, 62–100% of nondiapause‐bound fourth instars precociously pupated or remained as fourth instars, while 52–100% of diapause‐bound fourth instars did not molt to the fifth instar. Injection of these nondiapause‐ and diapause‐bound KK‐42‐fed fourth instars with ecdysone elicited a molt and resulted in the production of larval‐pupal intermediates. When mature fourth instar controls were similarly injected, they molted into normal fifth instars. These results support the view that KK‐42 delays/inhibits ecdysteroid production. Both eupyrene and apyrene spermiogenesis were prematurely initiated in nondiapause‐bound fourth instars that were fed on medium containing 160 ppm KK‐42. Fenoxycarb, a potent juvenile hormone mimic, rescued nondiapause‐bound fourth instars from precocious pupation. All fenoxycarbtreated larvae either molted to the fifth instar or remained as fourth instars and eventually died. These results support the view that treatment with KK‐42 inhibits JH production. When KK‐42 treatment was begun in the third instar, a considerable number of nondiapause‐bound and some diapause‐bound third instars precociously molted to the fifth instar. There was a correlation between weight and the incidence of precocious molting in that third instars destined to skip the fourth instar attained a weight, as pharate fifth instars, of two to three times more than pharate fourth instar controls. Similarly, fourth instars that were destined to undergo precocious pupation attained a weight, as pharate pupae, that was approximately two times more than pharate fifth instar controls. More potent analogues of KK‐42 may prove useful in controlling populations of 0. nubilalis by interfering with their growth, development, and metamorphosis. © 1995 Witey‐Liss, Inc.

This article is a US Government work and, as such, is, in the public domain in the United States of America.
Distribution of digestive proteinases in the alimentary tract of the european corn borer Ostrinia nubilalis (lepidoptera: Pyralidae)
Authors: Houseman Jon G. , Chin Phak‐San
Published: February 2005

The distribution of digestive proteinases in either the anterior and posterior midgut or between the midgut epithelium and ectoperitrophic and endo‐peritrophic spaces in the midgut were examined in the European corn borer, Ostrinia nubilalis. Trypsin, chymotrypsin, elastase, and aminopeptidase activities were the same in the anterior and posterior halves of the midgut. Of the total aminopeptidase activity, 95% was located in the midgut epithelium, and 90% of the trypsin, 97% of chymotrypsin, and 93% of the elastase activity were found in the midgut lumen. Trypsin, measured by hydrolysis of benzoyl‐L‐arginine ethyl ester, and chymotrypsin levels were significantly higher in the ectoperitrophic space compared to the endoperitrophic space. Digestion in the midgut is proposed to be sequential with tryptic digestion occurring in the endoperitrophic space. Ingested protein is digested further in the ectoperitrophic space by the action of elastase, chymotrypsin, and a second trypsin. Final digestion occurs by an intracellular aminopeptidase. © 1995 Wiley‐Liss, Inc.
Immunolocalization of a proton V‐ATPase in ovarian follicles of the tobacco hornworm Manduca sexta
Authors: Janssen I. , Hendrickx K. , Klein U. , de Loof A.
Published: February 2005

A monoclonal antibody, directed against an H+ translocating V‐ATPase of the midgut of Manduca sexta, has been used for immunolocalization studies in ovarian follicles and testes of Manduca sexta. In testes, no distinct staining above background levels was observed. In vitellogenic follicles, V‐ATPase immunoreactivity first appears in the cytoplasm of the trophocytes and then in the oocyte, but by far the strongest reaction is present in the region of the oolemma during endocytosis. All types of follicle cells surrounding both the oocyte and the trophocyte compartments show a distinct positive reaction. In the cylindrical follicle cells surrounding the oocyte, the immunoreactivity is clearly restricted to the basal part. Our results suggest an important role for V‐ATPase in vitellogenin uptake in Manduca, similar to that suggested on electro‐physiological grounds in Hyalophora cecropia. © 1995 Wiley‐Liss, Inc.
Temperature acclimation and seasonal responses by enzymes in cold‐hardy gall insects
Authors: Joanisse Denis R. , Storey Kenneth B.
Published: February 2005

Changes in the activity of over 20 enzymes of intermediary metabolism in 15°C or −4°C acclimated goldenrod gall moth (Epiblema scudderiana) and gall fly (Eurosta solidaginis) larvae were measured. Increased activities of glyco‐genolytic and hexose monophosphate shunt enzymes in cold‐acclimated Epiblema scudderiana suggest a role for coarse control in the conversion of glycogen reserves into glycerol cryoprotectant synthesis. In Eurosta solidaginis, high glycogen phosphorylase activity with decreased activities of glycolytic enzymes may account in part for the temperature‐dependent switch from glycerol to sorbitol synthesis in these larvae upon cold acclimation. Isoelectric focusing analyses of five enzymes in overwintering Epiblema scudderiana revealed transient mid‐winter changes in the isoelectric points of phosphofructokinase and pyruvate kinase, suggesting seasonal changes in the phosphorylation state of these enzymes. A distinct developmental pattern of aldolase isozymes suggests a role for a new isozyme during overwintering or upon spring emergence. Regulation of metabolism by changes in enzyme activities is indicated for both larvae. © 1995 Wiley‐Liss, Inc.
Characterization of midgut proteinase activities of white grubs: Lepidiota noxia, Lepidiota negatoria, and Antitrogus consanguineus (scarabaeidae, melolonthini)
Authors: McGhie Tony K. , Christeller John T. , Ford Rebecca , Allsopp Peter G.
Published: February 2005

The proteinases in the midguts of three scarab white grub species, Lepidiota noxia, L. negatoria, and Antitrogus consanguineus, were investigated to classify the proteinases present and to determine the most effective proteinase inhibitor for potential use as an insect control agent. pH activity profiles indicated the presence of serine proteinases and the absence of cysteine proteinases. This was confirmed by the lack of inhibition by specific cysteine proteinase inhibitors. Trypsin, chymotrypsin, elastase, and leucine aminopeptidase activities were detected by using specific synthetic substrates. A screen of 32 proteinase inhibitors produced 9 inhibitors of trypsin, chymotrypsin, and elastase which reduced proteolytic activity by greater than 75%. © 1995 Wiley‐Liss, Inc.
Phototoxicity of plant secondary metabolites: Insect and mammalian perspectives
Authors: Berenbaum May
Published: February 2005

Phototoxic chemicals produced by plants have been studied in a number of contexts, most notably as protective agents against mammalian and insect herbivores. Although there are commonalities in the responses of these two groups of herbivores to plant phototoxins, there are differences as well. Whereas a greater range of chemical classes has been demonstrated to display phototoxicity against insects, considerably more information is available on symptomology of phototoxicity and mechanisms of action in mammals. The commonalities include alterations in behavior following ingestion, notably photophobia, disruption of integumentary integrity following contact or ingestion, and metabolic detoxification following ingestion, in the case of furanocoumarins involving cytochrome P450 monooxygenases. Not yet known to exist in insects are phototoxin‐mediated effects on sensory (particularly visual) systems and phototoxicity resulting from abnormal chlorophyll metabolism. In order to gain greater understanding of the ecological significance of phototoxin‐mediated plant defense against both insects and mammals, there is a need for more studies centered on natural associations. © 1995 Wiley‐Liss, Inc.
Plant defenses against oxidative stress
Authors: Larson Richard A.
Published: February 2005

Many reactive oxygen species such as ozone, singlet oxygen, hydroxyl radical, and organic oxyradicals have been implicated in damage to plant organs and biopolymers such as chloroplasts, cell membranes, proteins, and DNA. The principal defenses against these reactive molecules and free radicals in plants include detoxifying enzymes (catalase, superoxide dismutase, etc.) and also lower molecular weight secondary products with antioxidant activity. These latter compounds include a great variety of phenolic compounds, carotenoids, nitrogenous, and sulfur‐containing materials. Some of the more important mechanisms of action of the secondary compounds will be discussed, with emphasis on the use of structural and kinetic data to identify the most effective antioxidants against peroxy radical‐induced damage, which is perhaps the most important of the oxidative stresses present in the usual environment of plants. © 1995 Wiley‐Liss, Inc.
Effects of dietary amino acids on the production of sexual morph by the green peach aphid, Myzus persicae
Authors: Fujita Akihiko , Mitsuhashi Jun
Published: February 2005

In order to complete a holocycle of the green peach aphid, Myzus persicae, on a synthetic diet, the effects of dietary amino acid contents on development of sexuals were investigated. For this purpose, the aphids were reared on holidic diets for two to three generations at 20°C under a scotophase of 15 h per diem. Under these conditions, the production of males by the aphids on a synthetic diet was very much poorer than those reared on radish seedling. On reducing the amino acid concentration of the diet, the proportion of males produced was comparable to that produced by aphids fed on radish seedlings. The obtained males were smaller and survived longer than those reared on radish seedling. Under the long night photoperiod and on the synthetic diet with reduced amino acids, gynoparae and then oviparae were also obtained. The oviparae were mated with the males grown on the synthetic diet, and laid eggs. The eggs, however, did not turn dark in color, and perished. © 1995 Wiley‐Liss, Inc.
Termination of vitellogenesis in follicles of the moth, Plodia interpunctella: Changes in oocyte and follicular epithelial cell activities
Authors: Zimowska Grażyna , Shirk Paul D. , Silhacek Donald L. , Shaaya Eli
Published: February 2005

The production and uptake of the follicular epithelium yolk protein (FEYP) is terminated coincident with the initiation of vitelline membrane synthesis in follicles of the Indianmeal moth, Plodia interpunctella (Hübner). This was determined by visualizing the cytolocalization of the FEYP subunits YP2 and YP4 using antisera to immunolabel ultrathin sections or whole‐mounted ovaries. Both subunits of FEYP were detectable in the Golgi apparatus and associated secretory granules of the follicular epithelial cells (FC) in vitellogenic follicles. Before the follicles entered the terminal growth phase, the oocytes began production of specialized organelles, late yolk spheres. Following the appearance of late yolk spheres in the oocyte, the FC initiated the production of vitelline membrane proteins and the rapid clearance of YP2 from their cytoplasm. No YP2 was detected in the Golgi apparatus or in the secretory granules of FC from follicles in terminal growth phase, although YP4 was detected in these organelles. The vitelline membrane of follicles in termal growth phase was a bilayered structure with an electron‐dense layer of vitelline membrane proteins that originated in the FC and an electron‐translucent layer containing yolk proteins. During this period, late yolk spheres were observed fused with the oolemma exposing and possibly releasing their contents to the electron‐translucent layer of the vitelline membrane. From this evidence, we suggest that during termination of vitellogenesis, the oocyte and FC work in concert to end uptake of yolk proteins and begin the synthesis of egg membranes, and that the oocyte contributes to the production of vitelline membrane by the release of previously sequestered yolk proteins. © 1995 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Multicellular‐vesicle‐promoting polypeptide from Trichoplusia ni: Tissue distribution and N‐terminal sequence
Authors: Ferkovich Stephen M. , Miller Stephen G. , Oberlander Herbert
Published: February 2005

An N‐terminal amino acid sequence of a 16.9 kDa hemolymph polypeptide, “Vesicle Promoting Factor” (VPF) from Trichoplusia ni, revealed a high sequence homology (70%) with Manduca sexta apolipophorin‐III. A polyclonal antibody developed against VPF, however, was not immunoreactive with either purified M. sexta or T. ni apolipophorin‐III. Immunoblots of tissue homogenates of T. ni indicated that VPF was present in imaginal wing discs, central nervous system (CNS), silk glands, midgut and hemocytes from fifth instar larvae, and also in the IAL‐TND1 cell line which can grow as either fluid‐filled multicellular vesicles or multicellular aggregates. VPF was also detected immunologically in the hemolymph of adults of T. ni, and in hemolymph of adults and larvae of Galleria mellonella and Heliothis virescens. Testes, midgut, hemocytes, and wing discs, but not Malpighian tubules, of T. ni released VPF into tissue culture medium during a 3 h incubation period. © 1995 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Identification, characterization, and developmental profile of a high molecular weight, juvenile hormone‐binding protein in the hemolymph of the migratory grasshopper, Melanoplus sanguinipes
Authors: Ismail Sheikh M. , Gillott Cedric
Published: February 2005

In the hemolymph of Melanoplus sanguinipes, a high molecular weight juvenile hormone binding protein (JHBP) was identified by photoaffinity labelling and found to have a Mr of 480,000. The JHBP, purified using native gel electrophoresis followed by electroelution, has an equilibrium dissociation constant for JH III of 2.1 nM and preferentially binds JH III over JH I. Antibody raised against JHBP recognized only the 480,000 band. Under denaturing conditions the native JHBP gave a single band with a Mr 78,000. The antibody against native JHBP recognized only the 78,000 protein in SDS‐treated hemolymph samples, indicating that JHBP is a hexamer in this species. The concentration of JHBP fluctuates in both the sexes during nymphal and adult development in parallel with total protein content of hemolymph. © 1995 Wiley‐Liss, Inc.
Hormonal regulation of sex pheromone biosynthesis in the turnip moth, Agrotis segetum
Authors: Zhu Junwei , Millar Jocelyn , Löfstedt Christer
Published: February 2005

Pheromone production in the female turnip moth, Agrotis segetum, is under the control of a brain factor. This factor was demonstrated to be a proteinaceous substance termed pheromone biosynthesis activating neuropeptide‐like substance (PBAN‐like substance). The sex pheromone of Swedish A. segetum includes (Z)‐5‐decenyl acetate, (Z)‐7‐dodecenyl acetate, and (Z)‐9‐tetradecenyl acetate as major components. Decapitation of a female decreased pheromone production significantly. Pheromone production was restored by injection of homogenates of either male or female brain‐suboesophageal ganglion or the corpora cardiaca alone. Pheromonotropic activity was also found in homogenates of the female thoracic ganglion and abdominal ganglion that were obtained during scotophase. Injection of female brain and thoracic ganglion homogenates made from insects during the scotophase induced two and four times as much Z7‐12:OAc, respectively, as injection with similar homogenates from photophase. As little as one‐eighth female equivalent (FE) brain homogenate was sufficient to increase the amount of Z7‐12:OAc. The effect of brain homogenate on pheromone titer reached its maximum after 30 min. The activity of the PBAN‐like substance present in female brain extracts was not correlated to the age of the donor. Injection of hemolymph collected during either photophase or scotophase into decapitated females did not increase the pheromone titer. The target site of the PBAN‐like substance was not the pheromone gland, and the ventral nerve cord was not involved in the transportation of the PBAN‐like substance, which implies a mode of action different from what has been reported in other moths. Brain homogenates obtained during photophase from females of African A. segetum, Spodoptera littoralis, or Ostrinia nubilalis as well as synthetic Bombyx‐PBAN also induced pheromone production in decapitated Swedish female A. segetum. © 1995 Wiley‐Liss, Inc.
Genetic and molecular studies of apterous: A gene implicated in the juvenile hormone system of Drosophila
Authors: Shtorch Atalia , Werczberger Ruth , Segal Daniel
Published: February 2005

The apterous (ap) gene in Drosophila melanogaster encodes a homeodomain transcription factor. It is required for the development of the wings and of a subset of embryonic muscles. The gene has been implicated in the juvenile hormone (JH) system because mutations in ap lead to JH deficiency, and are associated with defective histolysis of the larval fat body, arrested vitellogenesis, sterility, and aberrant sexual behavior, all of which are dependent on JH.

We describe here the use of hemizygotes and germ‐line clones, of X‐ray‐and hybrid dysgenesis‐induced lethal ap alleles to determine the primary role of the gene during development. We find that ap lethality is polyphasic, but occurs primarily at the larval and pupal stages. The lethal phenotype is not associated with any overt morphological abnormality, suggesting that death occurs from a systemic malfunction. Strong interallelic complementation for the wing phenotype was found between some ap mutations induced by hybrid‐dysgenesis. By Northern blot analysis, we demonstrate an increase in ap expression in pupae and adults as compared to embryos and larvae, suggesting that it is developmentally regulated. Finally, primer extension is used to determine the transcription start site of the gene. © 1995 Wiley‐Liss, Inc.
Uses of vaccinia virus as a vector for the production of live recombinant vaccines
Authors: Smith Geoffrey L. , Moss Bernard
Published: February 2005

Vaccinia virus, the world's oldest vaccine, was used originally for the eradication of smallpox. It is now being genetically engineered to create new live vaccines for use against other infectious agents of medical and veterinary importance. Genes coding for antigens of several pathogens have been linked to vaccinia virus transcriptional regulatory signals and inserted into the vaccinia virus genome. The resultant recombinant viruses are infectious, express the foreign gene, stimulate specific immune responses in vaccinated animals and can protect against disease caused by the corresponding pathogen.
Newly discovered activities for calcitriol (1,25‐dihydroxyvitamin D3): Implications for future pharmacological use
Authors: Simpson Robert U. , Weishaar Ronald
Published: February 2005

Recent studies have yielded new insights into the critical importance of adequate vitamin D3 intake and metabolism. Investigations of the actions of 1,25‐dihydroxyvitamin D3 (calcitriol) on novel target tissues has revealed that this hormone has functions other than its recognized action in regulating blood calcium and phosphate levels. Reports have characterized calcitriol receptors and activities in organs and tissues as diverse as pancreas, skeletal and heart muscle, blood cells, brain, skin, pituitary, parathyroid, kidney, bone and intestine. These studies suggest functions for calcitriol as varied as the regulation of insulin and prolactin secretion, muscle contractility, immune cell metabolism, melanin synthesis and differentiation of blood cells. This information may ultimately help us to understand the etiologies of several kinds of organ dysfunction and lead to the development of tissue‐specific agents for new therapies.
Molecular biology of T‐cell‐derived lymphokines: A model system for proliferation and differentiation of hemopoietic cells
Authors: Arai K. , Yokota T. , Miyajima A. , Arai N. , Lee F.
Published: February 2005

Many lymphokine genes have now been cloned from activated T cells and their products have been expressed in mammalian cells. Use of these recombinant lymphokines has provided the opportunity to evaluate both the spectrum of their biological activities and the mechanisms of their action in promoting proliferation and differentiation of hemopoietic and lymphoid cells. Characterization of the structure of lymphokine genes will provide information about their regulated expression in T‐cell activation.
Antibodies to DNA
Authors: Anderson Wayne F. , Cygler Miroslaw , Braun Ralph P. , Lee Jeremy S.
Published: February 2005

Antibodies that are specific for DNA provide an excellent system for studying the protein‐nucleic acid interactions that allow proteins to recognize specific DNA structures or sequences.
Mechanisms underlying induction and maintenance of long‐term potentiation in the hippocampus
Authors: Lynch M. A.
Published: February 2005

Long‐term potentiation (LTP) in the hippocampus is accompanied by a number of changes on both sides of the synapse. It is now generally considered that the trigger for initiating LTP is the entry of calcium into the postsynaptic area through the NMDA‐associated channel while the mechanism(s) underlying the maintenance of LTP are less well understood and probably involve contributions from both sides of the synapse.
Molecular insights into breast cancer from transgenic mouse models
Authors: Dickson Robert B. , Gottardis Macro M. , Merlino Glenn T.
Published: February 2005

We desperately need to know more of the biological details of the onset and progression of breast cancer. The disease is of startlingly high incidence (approaching 1 in 9 women), our current therapies for the disease are inadequate once it has metastasized, and the disease is characterized by excessive morbidity and mortality.

Most of the growth and differentiation of the mammary gland occurs relatively late in life: during sexual maturation, and then cyclically during pregnancy and lactation. Normal as well as malignant growth is regulated by endocrine hormones as well as by local tissue factors, such as polypeptide growth factors, Cancer seems to progress as hyperplastic ductal or lobular epithelial growth, acquiring progressive genetic changes (including those of oncogenes and tumor suppressor genes) leading to clonal outgrowths of progressively more malignant cells. The nature of proliferative controls and the relevant genetic changes are the subjects of the current review.
Evolution of the vertebrate Hox homeobox genes
Authors: Krumlauf Robb
Published: February 2005

One of the most remarkable recent findings in developmental biology has been the colinear and homologous relationships shared between the Drosophila HOM‐C and vertebrate Hox homeobox gene complexes. These relationships pose the question of the functional significance of colinearity and its molecular basis. While there was much initial resistance to the validity of this comparison, it now appears the Hox/HOM homology reflects a broad degree of evolutionary conservation which has reawakened interest in comparative embryology and evolution.

The evolutionary conservation of protein motifs in many gene families (including those for growth factors, secreted and membrane bound signalling factors, adhesion molecules, cytoplasmic receptor kinases, nuclear receptors and transcription factors) has lead to speculation on the extent to which these homology relationships represent common developmental processes and underlying molecular mechanisms. Structural identities in a protein may indicate the biochemical/molecular function that a protein plays in cellular and developmental processes, without reflecting a conserved role in a cascade of developmental events. However, the analysis of genes encoding transcription factors has provided evidence suggesting that there are gene complexes in arthropods and vertebrates which are true homologues and which may share common roles in the specification of regional identity along embryonic A‐P axis. These genes comprise the Box/HOM‐C homeotic complexes. This review will detail some of the evidence for this proposed relationship and will speculate on the functional implications.
Meiosis, mitosis and microtubule motors
Authors: Sawin Kenneth E. , Endow Sharyn A.
Published: February 2005

A framework for understanding the complex movements of mitosis and meiosis has been provided by the recent discovery of microtubule motor proteins, required for the proper distribution of chromosomes or the structural integrity of the mitotic or meiotic spindle. Although overall features of mitosis and meiosis are often assumed to be similar in mechanism, it is now clear that they differ in several important aspects. These include spindle structure and assembly, and timing of chromosome segregation to opposite poles. Here we review progress in the functional characterization of several newly identified microtubule motor proteins, emphasizing their possible roles in spindle structure and function.
Differential repair of excision gaps generated by transposable elements of the ‘Ac family’
Authors: Rommens Caius M. T. , Van Haaren Mark J. J. , Nijkamp H. John J. , Hille Jacques
Published: February 2005

Studies on transposable elements of the Ac family have led to different models for excision gap repair in either plants or Drosophila. Excision products generated by the plant transposable elements Ac and Tam3 imply a more or less straightforward ligation of broken ends; excision products of the Drosophila P element indicate the involvement of ‘double‐strand break’ (DSB) repair. Recent findings that excision products of Ac and Tam3 can also contain traces of the element ends indicate, however, that DSB repair might be an alternative repair mechanism in plants. A functional DSB repair mechanism in plants can also be deduced from the observed rapid increases of Ac copy number during plant development and from the involvement of Ac in the generation of internal Ac deletions. On the other hand, alternative repair mechanisms may also be functional in Drosophila, because some of the ‘footprints’ generated upon P excision can be explained by a mechanism that has been postulated for excision gap repair in plants. It is concluded that plants and Drosophila can use similar repair mechanisms, but that the predominance of a certain repair mechanism is determined by the host.
Multi‐allelic self‐incompatibility polymorphisms in plants
Authors: Charlesworth Deborah
Published: February 2005

The multi‐allelic self‐incompatibility polymorphisms in angiosperms have long interested geneticists and population geneticists, but the limits of classical genetic resolution were reached many years ago. In recent years, new progress has been made by molecular genetic approaches. Intriguing similarities to and differences from the fungal systems are emerging. The polymorphism at these loci is now known to be even more baroque than appeared from classical genetic studies. Alleles differ so much at the level of both the DNA and protein sequence that they would be difficult to recognise as products of the same locus, were it not for the presence of certain conserved regions. Despite the successes of the recent work, the locus responsible for the specificity of the incompatibility reaction in pollen, and the mechanism of self‐incompatibility, remain elusive.
The role of thymidylate synthase as an RNA binding protein
Authors: Chu Edward , Allegra Carmen J.
Published: February 2005

Thymidylate synthase plays a central role in the biosynthesis of thymidylate, an essential precursor for DNA biosynthesis. In addition to its role in catalysis and cellular metabolism, it is now appreciated that thymidylate synthase functons as an RNA binding protein. Specifically, thymidylate synthase binds with high affinity to its own mRNA, resulting in translational repression. An extensive series of experiments has been performed to elucidate the molecular elements underlying the interaction between thymidylate synthase and its own mRNA. In addition to characterization of the underlying cis‐ and trans‐acting elements, recent studies have shown that thymidylate synthase has the capacity to bind specifically to other cellular RNA species. While the biological significance of these other RNA/thymidylate synthase interactions remains to be defined, this work suggests a potential role for TS in coordinately regulating several critical aspects of cellular metabolism.
The role of chromosome ends during meiosis inCaenorhabditis elegans
Authors: Wicky Chantal , Rose Ann M.
Published: February 2005

Chromosome ends have been implicated in the meiotic processes of the nematodeCaenorhabditis elegans. Cytological observations have shown that chromosome ends attach to the nuclear membrane and adopt kinetochore functions. In this organism, centromeric activity is highly regulated, switching from multiple spindle attachments all along the chromosome during mitotic division to a single attachment during meiosis.C. eleganschromosomes are functionally monocentric during meiosis. Earlier genetic studies demonstrated that the terminal regions of the chromosomes are not equivalent in their meiotic potentials. There are asymmetries in the abilities of the ends to recombine when duplicated or deleted. In addition, mutations in single genes have been identified that mimic the meiotic effects of a terminal truncation of the X chromosome. The recent cloning and characterization of theC. eleganstelomeres has provided a starting point for the study of chromosomal elements mediating the meiotic process.
The biogenesis of lysosomes: Is it a kiss and run, continuous fusion and fission process?
Authors: Storrie Brian , Desjardins Michel
Published: February 2005

Molecules are transferred to lysosomes, the major, acid pH, digestive compartment in eukaryotic cells, by a complex series of pathways that converge at a late endosome/prelysosomal compartment. Here, we discuss the relationship between this compartment and the lysosome. We propose that lysosomes are maintained within cells by a repeated series of kiss and run, transient fusion and fission processes with the late endosome/prelysosome compartment. Directionality to these processes may be conferred by pH gradients and retrieval mechanisms. The future challenge in testing this and any other proposed hypothesis for lysosomal biogenesis will be the establishment of molecular mechanisms.
The vagaries of variegating transgenes
Authors: Martin David I. K. , Whitelaw Emma
Published: February 2005

Expression of transgenes in mice, when examined with assays that can distinguish individual cells, is often found to be heterocellular, or variegated. Line‐to‐line variations in expression of a transgene may be due largely to differences in the proportion of cells in which it is expressed. Variegated silencing by centromeric heterochromatin is well described, but other factors may also affect transgene silencing in mice. Tandem arrays of transgenes themselves form heterochromatin, and some cell lineages may tend to silence transgenes because of extensive facultative heterochromatin in their nuclei. The cis‐acting transcriptional control elements within a transgene inhibit silencing, and strainspecific differences in chromatin proteins may strongly influence the extent of variegation. The accessibility of multiple differentiated cell lineages in mice suggests that they may provide a tool for dissecting the role of chromatin‐mediated silencing in cell differentiation and tissue‐specific gene expression.
Drosophila Hox complex downstream targets and the function of homeotic genes
Authors: Graba Yacine , Aragnol Denise , Pradel Jacques
Published: February 2005

Hox complex genes are key developmental regulators highly conserved throughout evolution. The encoded proteins share a 60‐amino‐acid DNA‐binding motif, the homeodomain, and function as transcription factors to control axial patterning. An important question concerns the nature and function of genes acting downstream of Hox proteins. This review focuses on Drosophila, as little is known about this question in other organisms. The noticeable progress gained in the field during the past few years has significantly improved our current understanding of how Hox genes control diversified morphogenesis. Here we summarise the strategies deployed to identify Hox target genes and discuss how their function contributes to pattern formation and morphogenesis. The regulation of target genes is also considered with special emphasis on the mechanisms underlying the specificity of action of Hox proteins in the whole animal.
Age changes in the lumbar intervertebral disc studied with magnetic resonance and cryomicrotomy
Authors: Wagner Marvin , Sether Lowell A. , Yu Shiwei , Ho Peter S. P. , Haughton Victor M.
Published: February 2005

This is an original evaluation made on the correlation between sagittal gross and histologic cryomicrotome sections and magnetic resonance (MR) images of the lumbar intervertebral discs according to age groups. Age‐related structural changes were recognized in the anatomic sections and MR images of the discs in cadavers from birth to 73 years of age. In T2‐weighted MR images, the nucleus and fibrocartilaginous inner anulus have a bright signal while the peripheral annular fibers have a low signal intensity. With aging the discs become progressively more fibrous: the peripheral anulus widens and becomes densely fibrous and the inner anulus extends centrally to encroach upon the nucleus, sometimes producing a bilobed nucleus. In the newborn the components of the disc are sharply demarcated with a large, centrally located nucleus pulposus and a relatively narrow anulus fibrosus. In the adult, the nucleus and inner anulus continue to have a relatively bright signal in MR images and characteristically contain a dark band of low signal intensity which does not correspond to clefts or tears of the disc but to increased fibrous tissue content. The thickened peripheral annular fibers have a very low signal intensity. By the eighth decade of life the discs have a very high fibrous content throughout, indicated in MR images by a decreased signal intensity with no sharp distinction between nucleus and anulus in the anatomic sections. The dark band in the central portion of the disc remains as a characteristic feature in MR images of the adult disc. Degenerative changes in the discs are identified in MR images by contrasting signal intensities.
Rotation‐plasty: Surgical technique of resection and reconstruction in the treatment of osteosarcoma about the knee in children
Authors: Frassica Frank J. , Schwartz Herbert S. , Pairolero Peter C. , Sim Franklin H.
Published: February 2005

Resection of malignant tumors about the knee, followed by reconstruction of the lower limb by rotating it through an arc of 180 degrees is becoming a popular method of treatment of osteosarcoma in growing children. Following rotation, the rotated ankle functions as the knee joint, powering a custom‐made prosthesis. The functional result is superior to above‐knee amputation with better propioceptive feedback and the absence of phantom limb pain. The children are able to climb stairs well and participate in running sports.

The surgical technique is demanding, requiring a precise knowledge of the surgical anatomy. To be successful, the sciatic, peroneal, and tibial nerves must be preserved. The femoral and popliteal artery may be resected and reconstructed if necessary. The remaining growth of the child is determined so that the rotated ankle can be positioned at the level of the contralateral normal knee.
Anatomic variations of the phrenic nerve at the superior thoracic aperture (thoracic inlet): Implications for the cardiothoracic surgeon
Authors: LoCicero Joseph , Hoyne William P. , LoCicero Martha S. , Cochard Larry , Sanders John H.
Published: February 2005

Routine use of the internal thoracic (mammary) artery (ITA) in coronary revascularization has prompted surgeons to seek ways to increase its length and mobility while avoiding phrenic‐nerve (PN)injury related to dissection of the ITA to its origin. Because no clear anatomic description of the PN/ITA relationship exists, we investigated the course of the PN through the superior thoracic aperture (thoracic inlet) and its proximity to the origin of the ITA in 51 cadavers. The ITA coursed posterior to anterior as it crossed the subclavian vein and the PN, passing between the subclavian artery and vein, was lateral to the origin of the ITA (100%). The superior/inferior position of the PN to the ITA is variable. The PN passed superior and medial to the ITA (66%) but was not consistent from side to side in the same cadaver. The PN passed lateral and inferior to the IMA in the right hemithorax (27%) and in the left (40%). A bilateral superior/medial relationship was found in 50% of cadavers and a bilateral inferior/lateral one in 20%. The surgical implications of this anatomic finding are that the PN is vulnerable to injury when it is inferior to the ITA as it passes from lateral to medial through the superior thoracic aperture (thoracic inlet) and ITA dissection is carried past the posterior border of the subclavian vein; 1 cm of soft tissue will protect the PN if dissection ends at the anterior border of the vein.
Clinical anatomy for surgical residents: A 10‐week course
Authors: Osuch Janet R. , Dean Kimberly B. , Carrow Rexford E. , Dean Richard E.
Published: February 2005

The limited exposure of medical students to gross anatomy has significant bearing on those students who elect a surgical career. In an effort to address this deficiency, a 10‐week, 50 hour clinically oriented anatomy course was developed for third year surgical residents. The aim of the course was to provide clinical interpretation of anatomy in the regions of head/neck, thorax, abdomen, pelvis/inguinal and extremities as it pertains to the challenges facing a surgeon. Each of 20, 2‐hour laboratory experiences was preceded by a brief presentation from a clinician who identified the surgical complexities of the area, to include: unique blood supply, intraorganal lobular anatomy or problems of exposure as it relates to operations. The constant interface with the Anatomist facilitated the learning experience which occurred in the laboratory. The relationship between operative challenges and structural knowledge provided the optimal learning experience for course participants. Problems encountered were primarily logistical in nature and will be addressed in future courses.
Ruptures of the anulus fibrosus of cervical intervertebral discs studied by cryomicrotomy and magnetic resonance
Authors: Sether Lowell A. , Yu Shiwei , Haughton Victor M. , Wagner Marvin
Published: February 2005

Degeneration of the anulus fibrosus in the cervical region has not been studied as systematically as in the lumbar intervertebral discs. We used cryomicrotomy and magnetic resonance (MR) to study the cervical discs in 18 cadavers. Three types of anular tears were identified: (1) a concentric tear due to delamination of the anulus, (2) a radial tear in which all layers of the anulus were disrupted, and (3) a transverse tear of the peripheral anulus. The latter two tear types could be demonstrated by MR. On the basis of their frequency the concentric and transverse tears are not likely symptomatic. Radial tears, which some investigators have suggested are symptomatic, may be studied clinically with MR.
Reliability and predictive capacity of examinations in anatomy and improvement in the reliability of viva voce (oral) examinations by the use of a structured rating system
Authors: Tutton P. J. M. , Glasgow E. F.
Published: February 2005

In the present paper the reliability and predictive capacity of multiple‐choice, essay, and viva voce (oral) examinations in anatomy are compared. In an attempt to improve the reliability of the viva, a structured rating system was designed. In the latter system candidates were rated separately for achievement under the headings of Factual Recall, Analysis and Interpretation of Data, Problem Solving, and Verbal Presentation. The predictive capacity of examinations in anatomy was estimated by calculating the correlation between scores in anatomy and the score obtained by the same students in final‐year medicine. The reliability coefficients of the examinations were estimated using the split‐halves technique, together with Spearman‐Brown formula in the case of the viva and the essay exam, and using the Kuder‐Richardson formula 20 for the multiple‐choice tests. The correlations between scores in anatomy examinations and final‐year medicine examinations show that scores from essay and viva voce examinations are better predictors of success later in the medical course than are scores from multiple‐choice examinations. The reliability coefficient of viva voce ( < 0.4) examinations is clearly less than that of either essay examinations (around 0.65) or multiple‐choice tests (usually > 0.8). However, the use of the structured rating procedure elevated the reliability coefficient of the viva voce examination from between 0.3 and 0.4 in the case of the unstructured examination to between 0.7 and 0.8 in the case of the structured examination.
Carotid endarterectomy: Importance of cranial nerve anatomy
Authors: Basile Richard M. , Sadighi Parvis J.
Published: February 2005

A retrospective study of 100 consecutive cases of carotid endarterectomy was performed. Special attention was given to the incidence, clinical significance, and prevention of cranial nerve injury. The operative mortality was 1%, and there were no perioperative strokes. There was clinical evidence of 22 cranial nerve injuries. Nineteen injuries were temporary, resulting in a 3% incidence of permanent cranial nerve deficit.

The clinical anatomy of cranial nerves encountered during carotid endarterectomy is reviewed. Technical suggestions to minimize cranial nerve injury based on a thorough knowledge of this anatomy are provided.

The relationship of laryngeal physiology and vagus nerve anatomy indicates that unilateral vocal cord dysfunction may be asymptomatic. Bilateral nerve injury can cause potentially fatal airway obstruction, which may be unrecognized until after the second operation. Preoperative laryngoscopy prior to carotid endarterectomy is suggested in patients with a history of prior cardiac or neck surgery and those scheduled for the second of staged bilateral carotid procedures.
Course of the recurrent laryngeal nerve relative to the tracheoesophageal plane and the axis of the trachea
Authors: Lekacos N. L. , Tzardis P. J. , Sfikakis P. G. , Helmis E. P. , Vlassis T. A. , Kalogeracos K. P.
Published: February 2005

An awareness of the surgical anatomy and the possible dispositions of the recurrent laryngeal nerve (RLN) is helpful in avoiding its injury during thyroidectomy.

The relationship of the RLN to the trachea and its course relative to the tracheoesophageal plane were studied in 151 patients undergoing thyroidectomy. One hundred sixty‐six (166) nerves were identified, 95 on the right and 71 on the left.

Most nerves, both on the right (59%) as well as the left (53.5%), ran posterior to the tracheoesophageal plane. Most right nerves (84.2%) had an oblique course in the frontal plane as related to the tracheal axis or midline (deviation); on the left, most nerves (57.8%) showed no significant deviation. The nerves were found to course from posterior to anterior in the sagittal plane as they ascended the neck in 52.5% of cases on the right (type II obliquity), whereas on the left, 50.7% of the nerves ran in this direction. Approximately 37.2% of the nerves on the right, and 40.8%, on the left, had no obliquity in the sagittal plane paralleling the tracheal axis.
Microcomputer reconstruction of pancreaticobiliary embryogenesis
Authors: Wind Gary , Allely Eric , Jenkins Donald
Published: February 2005

The origin, approximation, and fusion of the dorsal and ventral pancreatic anlage were reconstructed using new microcomputer methodology. Representative human embryos of Carnegie stage 15–17 were studied by digitizing serial contours and creating three‐dimensional computer models. Solid surface color displays showing multiple views of each reconstruction demonstrated developmental relationships and changes between these three critical stages. This exercise demonstrates the power of this new technology for clarifying morphological concepts in research and education.
Electron microscopic demonstration of Langerhans cells in human tonsillar epithelium
Authors: Chandi Grace , Indrasingh Inbam , Chandi S. M.
Published: February 2005

Langerhans cells are believed to play an important role in cutaneous immune responses. The tonsils likewise have been regarded as lymphoid tissue performing critical functions in the immune system. The present study was undertaken to determine whether Langerhans cells are present in tonsillar epithelium.

Samples of epithelium from four tonsils were processed and examined with an electron microscope. Cells morphologically typical of Langerhans cells were found to be present in the tonsillar epithelium.
Anatomical study of the arterial blood supply of the skin of the lower leg
Authors: Bankoul S. , Kubik S.
Published: February 2005

The arteries leaving the intermuscular fissures of the lower leg form six constant rows. Two further vascular groups emerge from the lateral and the medial heads of the gastrocnemius muscle. The vessels form a fine epifascial network, the radial and longitudinal meshes of which anastomose together. The epifascial network is complemented by a weaker, subfascial one. The arteries can be subdivided into cutaneous, musculocutaneous, and cutaneomuscular groups, corresponding to their supplying areas. A significant difference in vessel pattern could not be found between the left and the right lower leg of the same person. The different areas of supply are constant in the middle one‐third of the lower leg, but vary considerably in the upper one‐third and moderately in the lower one‐third. The borders of the different areas show interlocking patterns.