bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological Effects on Periplaneta americana of Bacillus sp. Exotoxin
Authors: LIM Chae Sik , HAN Weon Dong
Published: March 2007

ABSTRACT
This study was performed to evaluate the physiological effects of Bacillus sp. on Periplaneta americana. The insecticidal exotoxin was fractionated by ion‐exchange chromatography and gel filtration from Bacillus sp. cultivates. Lp2 among 4 lipoproteins showed markable increase after 24 hrs, but there was no change in glycoprotein. The enzyme activities of P. americana showed mostly decreasing pattern by treatment of exotoxin fractions. Protease activities decreased at 12 hrs after treatment in comparison with normal subjects. Amylase also showed decreasing pattern and maximal decline was observed after 12 hrs. Trehalase activities decreased at 6 hrs and 24 hrs. Invertase activities decreased from 6 hrs to 24 hrs, but recovered after 48 hrs. Amylase isozyme A1 and A2 disappeared and new isozyme appeared after 12 hrs with exotoxin treatment. Trehalase isozyme T1 and invertase I4 increased markedly after 12hrs. However, non‐specific esterase E1 disappeared after 24hrs.
Two New Records of Phycitine Moths (Lepidoptera, Pyralidae) in Korea
Authors: PAEK Mun‐Ki , CHA Jin‐Yeoul , BAE Yang‐Seop
Published: March 2007

ABSTRACT
Two species, Assara inouei Yamanaka and Assara pallidella Yamanaka, are newly added to the pyralid fauna of Korea, with redescriptions and illustrations of adult and genitalia.
Effects of Diflubenzuron on the Development of Bombyx mori (Lepidoptera: Bombycidae)
Authors: KIM Young Sub
Published: March 2007

ABSTRACT
This study was conducted to determine the effects of diflubenzuron (DFB) on the growth and development of the silkworm, Bombyx mori (L.). The DFB treatment extended abnormally the larval duration and affected negatively on larval spinning of the 5th instar. All the larvae treated with high DFB concentration (2.5 × 10‐1 and 2.5x 10‐1μg/μl) lost their spinning capability and finally died, whereas 62% of larvae treated with low DFB concentration (2.5 × 10‐1μg/μl)) spinned cocoon. The larval weights depended sensitively on the DFB treatment period rather than on the DFB concentration. The DFB treatment decreased the larval maturity less than 6% without regard to the concentration and treatment period. All the larva, when treated with DFB before the 5th days of the 5th instar, were not matured.
Evaluations on the Lethal, Choice and Secondary Effects of Four Insecticidal Baits against the German Cockroach (Blattaria, Blattellidae)
Authors: LEE Dong‐Kyu
Published: March 2007

ABSTRACT
The laboratory studies were carried out for evaluating control effects of four commercial insecticidal baits such as two different hydramethylnon [2.0%(AI)] products (DBK® and Combat‐Gold®), fipronil [0.05 %(AI)] (Combat‐Power®) and (0.6% chlorpyrifos [0.6%(AI)] (Raid‐Roachbait®) against German cockroaches (Blattella germanica). The control rates of four kinds of toxic baits were all 100.0% mortality of German cockroaches in 5 days after treatment. The results of chlorpyrifos and fipronil brought 100.0% mortalities in 2 to 3 days after treatment, respectively. After 3 day treatment, there was no significant difference of control effect among the four toxic baits. As a result of this study, fipnonil and chlorpyrifos showed faster killing action against German cockroaches than the two hydramethylnon formulation products. In the choice test, DBK® (hydramethylnon) (average 17.0 ind.) significantly attracted more German cockroaches than Combat‐Gold® (hydramethylnon) (avg. 7.0 ind.), Combat‐Power® (fipronil) (avg. 5.3 ind.) and Raid‐Roachbait® (chlorpyrifos) (avg. 3.3 ind.). The difference in attraction effects came 10 minutes after treatment. In order to evaluate the secondary killing effect of toxic baits by coprophagy against adult Blattella germanica, the comparative test was carried out. The adult mortality rates were significantly different among the four toxic baits showing 86.7% mortality for fipronil, 60.0% for hydramethylnon (DBK®), 30.0% for chlorpyrifos, and below 13.3% for hydramethylnon (Combat‐Gold®) in 6 days. During the first 12 days, fipronil showed the highest mortality rate (90.0%), followed by hydramethylnon (DBK®) (60.0%). The secondary killing effect of toxic baits by coprophagy appeared in all of the baits against adult Blattella germanica.
The Effect of Changes in Organic Nitrogen Concentration of Rumex obtusifolius L. on the Population Dynamics of Aphis rumicis L. (Homoptera: Aphididae)
Authors: KWON Ohseok
Published: March 2007

ABSTRACT
The study of plant‐herbivore dynamics was carried out using Aphis rumicis L. The insect is oligophagous to the genus Rumex. It utilizes its food plant by means of phloem sucking. Here, in this study, organic nitrogen as a form of a pellet fertilizer was used as a limiting factor. The major aim of the study is to find out the tripartite relationship among soil nitrogen concentration, the plant, and the insect. Observations were made from both the natural habitat site and the manipulated field site. The result shows that Aphis rumicis responded positively to increased N concentration of leaves (p< 0.005). The application of organic nitrogen did not alter the pattern of the population dynamics of Aphis rumicis over the study period. However, it may determine the time for the optimal exploitation of resources by the insect. It is also suggested that the growth efficiency of the insect relates to the C: N ratio in the phloem.
Notes on a Cicada Parasitic Moth in Korea (Lepidoptera: Epipyropidae)
Authors: JEON Jeong‐Bae , KIM Tae‐Woo , TRIPOTIN Pierre , KIM Jin‐Ill
Published: March 2007

ABSTRACT
The cicada parasitic moth Epipomponia nawai (Dyar) belonging to the family Epipyropidae is newly recorded from the Korean peninsula. Adults of both sexes, larva, and pupa are illustrated. Collecting data and host records for the species are also presented.
Labial Gland and Its Protein Patterns of Hydropsychid Caddisfly (Hydropsyche kozhantschikovi Martynov: Trichoptera)
Authors: PARK Sang‐Chan , KANG Seok Woo , HAN Sung Sik , WAGO Haruhisa
Published: March 2007

ABSTRACT
There is a pair of labial gland of hydropsychid caddisfly (Hydropsyche kozhantschikovi Martynov) larva. It is in ‘Z’ formation in the body and the total length is about 20 mm. Hydropsychid caddishfly larvae that were raised under the lab conditions were able to form a nest‐spining by connecting the small grains of sand provided. By repeatedly treating the extracted labial gland with methanol/D.W., the cell layer was removed. Accordingly, only the matrix within the labial gland that did not dissolve in water was obtained. The matrix inside the methanol/D.W. treated labial gland was dissolved with 5% acetic acid. Then the results of an acidic electrophoresis with a number of conditions indicated that 5% acetic acid/ 5 M urea/ 8% PAGE was the most effective. Moreover, the result of 2‐D PAGE on the labial gland of these hydropsychid caddisfly larva, the number of proteins in the labial gland including the cell layer was about 350 and the number of proteins in the labial gland treated with methanol/D.W. was about 80, showing a substantially small number of proteins.
Taxonomic Review and Revised Keys of the Korean Mosquitoes (Diptera: Culicidae)
Authors: REE Han‐Il
Published: March 2007

ABSTRACT
A bibliographic review on the Korean mosquitoes (Diptera: Culicidae) resulted in the recognition of 51 species and two forms of adult mosquitoes belonging to 10 genera, three subfamilies. Revised keys to genera and species of female adults of Korean mosquitoes are provided using available macro‐characters. Pictorial keys are also provided for easy usage.
New Record of the Genus Tympanophorus Nordmann (Coleoptera: Staphylinidae) in Korea
Authors: CHO Young Bok , SHIN Choru
Published: March 2007

ABSTRACT
The genus Tympanophorus Nordmann is recorded newly in Korea. Two species, Tympanophorus hayashidai Shibata and T. sauteri Bernhauer, are reported for the first time in Korea. The key, descriptions, and illustrations are presented.
Fine Structure of Elytral Punctures and Diffraction Gratings in Korean Sericinae (Coleoptera, Melolonthidae)
Authors: KIM Jin Ill , KIM A‐Young
Published: March 2007

ABSTRACT
The surface structures of the elytra in twenty two species belonging to the subfamily Sericinae (Coleoptera, Melolonthidae) were observed by scanning electron microscopy. For viewing specific characters, elytral punctures and diffraction gratings on interstitial surface were focused on. The elytral punctures of observed Sericid beetles have three representative forms: horseshoe, ocellus, and crease types. The diffraction gratings of the elytra show three distinctive patterns: regular and parallel, discontinued, and interconnected and curved. These patterns of elytral punctures and diffraction gratings considered to be useful for identification.
Pharmacological Study of Intracellular Second Messengers that Affect Active Ion Transport in the Midgut of Tobacco Hornworm, Manduca sexta
Authors: LEE Kyeong‐Yeoll
Published: March 2007

ABSTRACT
Midgut active ion transport changes during the final larval stage of the tobacco hornworm. The short‐circuit current (Isc) of the posterior midguts dissected from feeding fifth instars (day 2) is higher than that of midguts from wandering larvae (day 5). The Isc of midguts from day 2 larvae is inhibited by 1 mM cAMP and 0.1 mM cGMP, whereas the midguts from day 5 larvae are stimulated by cAMP but unaffected by cGMP. A similar pattern is observed if the midguts are exposed to the cyclic nucleotide derivative, 8‐bromo‐cGMP. Exposure to the calcium ionophore, A23187, or the endoplasmic calcium ATPase inhibitor, thapsigargin, slightly inhibited the Isc of day 2 larval midguts, but this inhibition was not significant. Pharmacological agents known to modulate the activities of protein kinase A, protein kinase C, or protein phosphatases did not change the Isc. These results indicate that midgut active ion transport is modulated by cyclic nucleotides, but the manner of the response depends on the developmental status of the insect.
Overexpression and Immunological Characterization of the Serine Protease AgSp24D from the Malaria Mosquito, Anopheles gambiae
Authors: CHUN Jaesun
Published: March 2007

ABSTRACT
Serine proteases are a class of proteolytic enzymes that play regulatory roles in protein processing and degradation. Previous molecular characterization of a mosquito serine protease, AgSp24D, indicated that it is a nondigestive chymotrypsin‐like enzyme that is developmentally regulated, and is strongly expressed during the adult stage. Since the biological role of AgSp24D is unknown, we were interested in further characterizing the gene product. Thus, a polyclonal antibody against an AgSp24D fusion protein was produced. The antiserum recognizes two polypeptides of 50 kDa and 60 kDa in immunoblots of whole body homogenates from adult mosquitoes. Western blot analysis showed the strongest signal in a homogenate of thoraces. The signal was also detected in the head, midgut, cuticle plus fat body, ovary, and Malpighian tubules. No signal was detected in the hemolymph. A comparison of Anopheles gambiae, Aedes aegypti, Armigeres subalbatus, Drosophila melanogaster, Acheta domesticus, Manduca sexta, and bovine cardiac muscle and skeletal muscle showed that the polyclonal antibody cross‐reacted to similarly sized polypeptides in all samples.
Development of Copris tripartitus (Coleoptera: Scarabaeidae) in Two Different Rearing Media
Authors: BANG Hea Son , WARDHAUGH K.G. , HWANG Seok Jo , KWON Oh Seok
Published: March 2007

ABSTRACT
Like many other sub‐social insects, Copris tripartitus Waterhouse requires parental care during the development period in the brood balls. Mass‐rearing is achieved by using indoor rearing systems and adding more dung after taking away the brood balls containing eggs. Without parental care, larvae are often affected by desiccation, as well as by fungal or sciarid fly intrusion of the brood balls. This study developed a good substitute for brood ball rearing medium. A significantly greater number of progeny survived to adulthood from broods produced by beetles reared on vermiculite medium (90.69±10.98%) than on peat moss medium (44.82±13.92%). Results of the study suggest that to protect the brood balls from desiccation and to produce healthy adults, 15‐20% moisture content vermiculite must be used as brood ball rearing medium for most species reared in the laboratory.
A Taxonomic Study of Immature Stage in Three Species of the Genus Protaetia Burmeister (Coleoptera: Scarabaeoidea, Cetoniidae) from Korea
Authors: KIM Mi Ae , LEE Hee A , PARK Hae Chul
Published: March 2007

ABSTRACT
ABSTRACT The third instar larvae of Korean Protaetia spp., P. brevitarsis seulensis (Kolbe), 1886, P. orientalis submarmorea (Burmeister), 1842, and P. mandschuriensis (Schürhoff), 1933, are described. The larva of the second species is the first record in this genus. A taxonomic key, descriptions, and illustrations of the three species are provided.
Purification and Characterization of Acid Phosphatase from the Egg of the Lady Beetle, Harmonia axyridis (Coccinellidae: Coleoptera)
Authors: LEE Jun Hyuk , PARK Yong Chul
Published: March 2007

Acid phosphatase (AP) in the egg of the lady beetle, Harmonia axyridis, was purified and characterized. Ammonium sulfate precipitation, CM column and isoelectrofocusing (IEF) were applied to purify an estimated molecular weight of 66 kDa AP. The purity was checked by SDS PAGE, native PAGE and Western blot. AP was detected in the hemolymph of the female and the egg, but not in the male on the blotting. Km of AP for a substrate, p‐nitrophenyl phosphate (p‐NPP), was 1.64 x 10‐4 M. AP had the optimum enzymatic activity at pH 3.5. In inhibition tests performed with various chemicals, ammonium molybdate suppressed 99% of the enzyme activity of AP even at the concentration of 5 x 10‐4 mM. AP was stable up to 50°C.
Silk Production after Mechanical Pulling Stimulation in the Ampullate Silk Glands of the Barn Spider, Araneus cavaticus
Authors: MOON Myung‐Jin , TILLINGHAST Edward K.
Published: March 2007

Synthesis of protein by the major ampullate silk glands in the barn spider, Araneus cavaticus was stimulated by depleting the storage of silk protein in the ampulla by mechanically pulling fiber from the spigot. After this treatment, fine structural changes of the glandular epithelium during silk production were examined using light and transmission electron microscopes. In the process of rapid production, major secretory silk was synthesized at the tail region via rER of glandular epithelial cells, and was transported into the ampulla region. The mature secretory product in glandular epithelium appears almost spherical vacuoles which were grown up by fusion with the surrounding small vesicles including the secretory silk. Unlike to a typical process of the secretion, the ampullate silk of tail region seems to bypass either concentrating or packaging steps by the Golgi apparatus. However there's no doubt that the Golgi apparatus also play an important role in the secretory process of the ampulla region. After mechanical pulling stimulation, both epithelia of ampulla and tail regions appeared as a thinner layer of columnar cells with less definitive cell membrane. There are few secretory droplets within these cells, thus causing this region to stain much lighter. It is obvious that the cell loses part of its cytoplasm in this process, and disorganization of the secretory product occurs when it is extruded from the cells by a apocrine release.
Taxonomic Study of Korean Oedipodinae (Orthoptera: Caelifera: Acrididae)
Authors: KIM Tae‐Woo , KIM Jin‐Ill
Published: March 2007

As a result of Korean Oedipodinae is taxonomically revised, eleven species are recognized and Microgastrimargus taeguensis Lee and Park 1992 is a new synonym of Oedaleus infernalis Saussure 1884. A key to Korean species of Oedipodinae, and description of a little known species Epacromius japonicus (Shiraki 1910) are provided.
Taxonomic Study of Korean Chrysochraontini (Orthoptera: Acrididae: Gomphocerinae)
Authors: KIM Tae‐Woo , KIM Jin‐Ill
Published: March 2007

Five species of Korean Chrysochraontini are recognized through the taxonomic investigation. Among them Chrysochraon dispar major Uvarov, 1925 is newly recorded from North Korea, and Euthystira pavlovskii Bey‐Bienko, 1954 is synonymized under Mongolotettix japonicus (Bolívar, 1898). A key is provided, and morphological variations of M. japonicus are discussed.
Microstructural Analysis of the Capture Thread Spinning Apparatus in Orb Web Spiders
Authors: MOON Myung‐Jin , KIM Tae‐Hyun
Published: March 2007

The microstructural characteristics of the capture thread production from silk glands in the orb web spiders were analyzed using scanning and transmission electron microscopes. Sticky and gluey capture threads of the web are originated from the silks of two flagelliform glands and four aggregate glands. They supply precursors of the secretory silks to a pair of characteristic “triad” spinning units on the posterior spinnerets. The aggregate gland is composed of large and multi‐lobed secretory region and thick excretory duct surrounded by large irregular nodules. The excretory duct of this gland basically consists of three superposed types of cells which are inner columnar epithelium, nodule forming cells and outer connectives. The nodules contain numerous mitochondria and glycogen particles within their cytoplasm and they are surrounded by the same sheath of thin connective tissues. Secretory region of the aggregate gland which produce water‐soluble components of the capture thread comprises discrete secretory vesicles and extensive rough endoplasmic reticulum. Characteristically, secretory droplets are formed without involvement of the Golgi complexes, suggesting that they do not play an important role in the processing of the capture threads. However the electron densities and internal textures of the granules are observed with diverse according to their maturation level. Finally, the secretory products are released by the mechanism of apocrine secretion losing part of their cytoplasm during this process.
Purification and cDNA Cloning of Lysozyme II from Cabbage Butterfly, Artogeia rapae Larvae
Authors: In Seok BANG , YOE Sung Moon
Published: March 2007

ABSTRACTLast instar larvae of cabbage butterflyArtogeia rapaerespond to injection of bacteria with a set of inducible antibacterial peptides/proteins. The inducible peptides/proteins are related to the known hinnavins (I and II) and lysozymes (I and II). The lysozyme II has been isolated by heat treatment, cation exchange, and reversed‐phase chromatography from immunized hemolymph of last instar larvae. The lysozyme II gene ofA. rapaewas isolated and its nucleotide sequence was determined by the RACE‐PCR from immunized fat body withE. coli.It has an open reading frame of 414 bp nucleotide corresponding to 138 amino acids including an 18 amino acid signal sequence. The molecular weight and the isoelectric point ofArtogeialysozyme II without a signal peptide were 13,649.38 Da and 9.11, respectively. It is great similarity withManducalysozyme among other lepidopteran.
Identification of Low Molecular Weight Diapause‐Associated Proteins of Two‐Spotted Spider Mite, Tetranychus urticae
Authors: Duck‐Oung JUNG , Kyeong‐Yeoll LEE
Published: March 2007

ABSTRACT Proteins in whole bodies of two‐spotted spider mites, Tetranchus urticae, were compared between non‐diapause and diapause conditions using one‐ and two‐dimensional electrophoresis. At one‐dimensional analysis diapausing mites synthesized several unique proteins that are higher in their quantity than non‐diapausing ones. Overall protein numbers in two‐dimensional gel show that diapause mites expressed fewer proteins than non‐diapausing ones. However, 25 proteins that have higher quantity in diapause were selected at the range of low molecular weight (5‐20 kDa). Among them 13 proteins were only present in diapause mites. Our results thus indicate some proteins uniquely expressed during diapause and may have specifie roles during long overwintering period.
A Taxonomic Report of Six Noctuidae Species (Lepidoptera) new to Korea
Authors: Jae‐Cheon SOHN , Laszlo RONKAY , Sung Soo KIM , Soowon CHO
Published: March 2007

ABSTRACT Six noctuid species: Ericeia pertendens(Walker), Nycteola costalis Sugi, Neustrotia albicincta (Hampson), Araeopteron flaccida Inoue, Feliniopisis indistans (Guenée), and Hadula stigmosa (Christoph), are newly recorded in the Korean fauna. The photographs of the adults and their genitalia are given for each species, together with notes on their bionomy and distribution.
On the Construction of Imputation Classes in Surveys
Authors: Haziza David , Beaumont Jean‐François
Published: March 2007

This paper explores the problem of the construction of imputation classes using the score method, sometimes called predictive mean stratification or response propensity stratification, depending on the context. This method was studied in Thomsen (1973), Little (1986) and Eltinge & Yansaneh (1997). We use a different framework to evaluate the properties of the resulting imputed estimator of a population mean. In our framework, we condition on the realized sample. This enables us to considerably simplify our theoretical developments in the frequent situation where the boundaries and the number of classes are sample‐dependent. We find that the key factor for reducing the non‐response bias is to form classes homogeneous with respect to the response probabilities and/or the conditional expectation of the variable of interest. In the latter case, the non‐response/imputation variance is also reduced. Finally, we performed a simulation study to fully evaluate various versions of the score method and to compare them with a cross‐classification method, which is frequently used in practice. The results showed the superiority of the score method in general.
Regional Inequalities in Consumption Patterns: A Multilevel Approach to the Case of Italy
Authors: Bono Filippa , Cuffaro Miranda , Giaimo Rosa
Published: March 2007

The main aim of this paper is to evaluate the disparities in the Italian regions on the demand side. In more detail, an attempt will be made to find if the consumption behaviour of Italian households is different in the regions. With this in mind, Istat's 2000 Italian Family Budget data set was analysed. The data in question, which were collected through a two‐stage sample over Italy's 20 regions, contains information regarding the expenses of approximately 23,000 households. In this analysis, both households and regions are considered as units: households are nested in the regions so that the basic data structure is hierarchical. In order to take this hierarchical structure into account, a multilevel model was used, making it possible for parameters to vary randomly from region to region. The model in question also made it possible to consider heterogeneity across different groups (regions), such as stochastic variation. First, regional inequalities were tested using a simple model in which households constituted the first level of analysis and were grouped according to their region (the second level). As a second step, and in order to investigate the interaction between geographical context and income distribution, another model was used. This was cross‐classified by income and regions. The most relevant results showed that there is wide fragmentation of consumption behaviour and, at the same time, various differentiated types of behaviour in the regions under analysis. These territorial differentials become clear from income class and items of consumption.
Bidirectional synaptic plasticity at nociceptive afferents in the rat central amygdala
Authors: De Armentia Mikel López , Sah Pankaj
Published: March 2007

Glutamatergic inputs arising from the parabrachial nucleus to neurons in the lateral sector of the central amygdala were studied in vitro. Tetanic stimulation of these inputs led to LTP that did not require activation of NMDA receptors or a rise of postsynaptic calcium. LTP was accompanied by a reduction in the paired‐pulse ratio, indicating that LTP results from an increase in transmitter release probability. Activation of adenylyl cyclase with forskolin potentiated these inputs with a similar reduction in paired‐pulse facilitation and occluded LTP induction. LTP was inhibited by the protein kinase A blocker H89. Low‐frequency stimulation led to LTD that required activation of postsynaptic NMDA receptors and a rise in postsynaptic calcium. There was no change in paired‐pulse facilitation with LTD. LTD was blocked by protein phosphatase blockers calyculin and okadaic acid. We conclude that parabrachial inputs to the lateral sector of the central amygdala show presynaptic LTP that requires activation of a presynaptic protein kinase A via a calcium‐dependent adenylyl cyclase while LTD at the same synapses is postsynaptic and requires a rise in postsynaptic calcium and activation of protein phosphatase.
Regulation of membrane potential and fluid secretion by Ca2+‐activated K+ channels in mouse submandibular glands
Authors: Romanenko Victor G. , Nakamoto Tetsuji , Srivastava Alaka , Begenisich Ted , Melvin James E.
Published: March 2007

We have recently shown that the IK1 and maxi‐K channels in parotid salivary gland acinar cells are encoded by the KCa3.1 and KCa1.1 genes, respectively, and in vivo stimulated parotid secretion is severely reduced in double‐null mice. The current study tested whether submandibular acinar cell function also relies on these channels. We found that the K+ currents in submandibular acinar cells have the biophysical and pharmacological footprints of IK1 and maxi‐K channels and their molecular identities were confirmed by the loss of these currents in KCa3.1‐ and KCa1.1‐null mice. Unexpectedly, the pilocarpine‐stimulated in vivo fluid secretion from submandibular glands was essentially normal in double‐null mice. This result and the possibility of side‐effects of pilocarpine on the nervous system, led us to develop an ex vivo fluid secretion assay. Fluid secretion from the ex vivo assay was substantially (about 75%) reduced in animals with both K+ channel genes ablated – strongly suggesting systemic complications with the in vivo assay. Additional experiments focusing on the membrane potential in isolated submandibular acinar cells revealed mechanistic details underlying fluid secretion in K+ channel‐deficient mice. The membrane potential of submandibular acinar cells from wild‐type mice remained strongly hyperpolarized (−55 ± 2 mV) relative to the Cl− equilibrium potential (−24 mV) during muscarinic stimulation. Similar hyperpolarizations were observed in KCa3.1‐ and KCa1.1‐null mice (−51 ± 3 and −48 ± 3 mV, respectively), consistent with the normal fluid secretion produced ex vivo. In contrast, acinar cells from double KCa3.1/KCa1.1‐null mice were only slightly hyperpolarized (−35 ± 2 mV) also consistent with the ex vivo (but not in vivo) results. Finally, we found that the modest hyperpolarization of cells from the double‐null mice was maintained by the electrogenic Na+,K+‐ATPase.
PKC and polyamine modulation of GluR2‐deficient AMPA receptors in immature neocortical pyramidal neurons of the rat
Authors: Shin Jieun , Shen Fran , Huguenard John
Published: March 2007

AMPA receptors (AMPARs) mediate the bulk of fast synaptic excitation in the CNS. We have recently shown that AMPAR‐dependent synaptic transmission in immature neocortical pyramidal neurons is mediated by GluR2‐deficient receptors that can be modulated by intra‐ or extracellular polyamines (PAs). Phosphorylation of AMPARs, e.g. by PKC, can lead to enhanced excitation, and PAs are known to modulate PKC activity. Therefore, PAs and PKC might interact to influence AMPAR function. To test this hypothesis, we made whole cell recordings from immature (P12–14) layer V pyramidal neurons and assayed two measures of PA influence on synaptic AMPAR function – inward rectification and use‐dependent unblock (UDU), with the latter assayed by differences in rectification between a pair of EPSCs evoked at short (50 ms) latencies. We have previously shown that EPSCs in immature pyramidal neurons displayed inward rectification, which was enhanced by intracellular spermine, as was UDU. Staurosporin (ST), a PKC inhibitor, reversed the effect of PA on rectification and UDU, suggesting that PKC modulates postsynaptic activation of AMPARs. Similarly, polyamine‐dependent rectification of spontaneous EPSCs was reversed by treatment with ST or GFX109203X, a specific PKC inhibitor. Chelating intracellular Ca2+ with BAPTA reproduced the effects of ST. In addition, PA immunoreactivity in layer V pyramidal neurons was reduced by PKC inhibition indicating that PKC activity influences PA metabolism. Taken together, these data support the involvement of postsynaptic PKC activation in both the inward rectification and UDU of EPSCs in immature rat cortex, and suggest an important mechanism by which excitatory synaptic transmission can be dynamically modulated by changes in either [Ca2+]i or [PA]i.
The effect of external sodium concentration on sodium–calcium exchange in frog olfactory receptor cells
Authors: Antolin Salome , Matthews Hugh R.
Published: March 2007

During the response of vertebrate olfactory receptor cells to stimulation, Ca2+ enters the cilia via cyclic nucleotide‐gated channels and is extruded by Na+–Ca2+ exchange. The rise in Ca2+ concentration opens a Ca2+‐activated Cl− conductance which carries most of the inward receptor current. The dependence of Ca2+ extrusion upon external Na+ concentration was studied by using the falling phase of the Ca2+‐activated Cl− current following a brief exposure to the phosphodiesterase inhibitor IBMX to monitor indirectly the decay in intraciliary Ca2+ concentration. External Na+ concentration was reduced by partial substitution with guanidinium, an ion which permeates the cyclic nucleotide‐gated channel but does not support Na+–Ca2+ exchange. The time constant describing the decay in current following IBMX stimulation was surprisingly little affected by substitution of external Na+, being substantially retarded only when its concentration was reduced to a third or less of its normal value in Ringer solution. When the cilia were returned to Ringer solution after a period in reduced‐Na+ solution, the time constant for the final decay of current was similar to that seen when returning immediately to IBMX‐free Ringer solution. This observation suggests that Ca2+ extrusion via Na+–Ca2+ exchange dominates the falling phase of the response to IBMX, which can therefore be used to assess exchanger activity. Rate constants derived from the time constants for current decay at different external Na+ concentrations could be fitted by the Hill equation with a Kd of 54 ± 4 mm and Hill coefficient of 3.7 ± 0.4. The cooperativity of the dependence upon external Na+ concentration indicates that at least three Na+ ions enter for each exchanger cycle, while the high affinity for external Na+ contrasts with the photoreceptor and cardiac exchangers. The functional importance of this observation is that the relative insensitivity of the Na+–Ca2+ exchanger to external Na+ concentration allows normal response termination even following partial dilution or concentration of the olfactory mucus.
Multiple High-Throughput Analyses Monitor the Response of
E. coli
to Perturbations
Authors: Ishii Nobuyoshi , Nakahigashi Kenji , Baba Tomoya , Robert Martin , Soga Tomoyoshi , Kanai Akio , Hirasawa Takashi , Naba Miki , Hirai Kenta , Hoque Aminul , Ho Pei Yee , Kakazu Yuji , Sugawara Kaori , Igarashi Saori , Harada Satoshi , Masuda Takeshi , Sugiyama Naoyuki , Togashi Takashi , Hasegawa Miki , Takai Yuki , Yugi Katsuyuki , Arakawa Kazuharu , Iwata Nayuta , Toya Yoshihiro , Nakayama Yoichi , Nishioka Takaaki , Shimizu Kazuyuki , Mori Hirotada , Tomita Masaru
Published: March 2007

Analysis of cellular components at multiple levels of biological information can provide valuable functional insights. We performed multiple high-throughput measurements to study the response of
Escherichia coli
cells to genetic and environmental perturbations. Analysis of metabolic enzyme gene disruptants revealed unexpectedly small changes in messenger RNA and proteins for most disruptants. Overall, metabolite levels were also stable, reflecting the rerouting of fluxes in the metabolic network. In contrast,
E. coli
actively regulated enzyme levels to maintain a stable metabolic state in response to changes in growth rate.
E. coli
thus seems to use complementary strategies that result in a metabolic network robust against perturbations.
Control of Stress-Dependent Cardiac Growth and Gene Expression by a MicroRNA
Authors: van Rooij Eva , Sutherland Lillian B. , Qi Xiaoxia , Richardson James A. , Hill Joseph , Olson Eric N.
Published: March 2007

The heart responds to diverse forms of stress by hypertrophic growth accompanied by fibrosis and eventual diminution of contractility, which results from down-regulation of α–myosin heavy chain (αMHC) and up-regulation of βMHC, the primary contractile proteins of the heart. We found that a cardiac-specific microRNA (miR-208) encoded by an intron of the α
MHC
gene is required for cardiomyocyte hypertrophy, fibrosis, and expression of β
MHC
in response to stress and hypothyroidism. Thus, the α
MHC
gene, in addition to encoding a major cardiac contractile protein, regulates cardiac growth and gene expression in response to stress and hormonal signaling through miR-208.
Negative Refraction at Visible Frequencies
Authors: Lezec Henri J. , Dionne Jennifer A. , Atwater Harry A.
Published: March 2007

Nanofabricated photonic materials offer opportunities for crafting the propagation and dispersion of light in matter. We demonstrate an experimental realization of a two-dimensional negative-index material in the blue-green region of the visible spectrum, substantiated by direct geometric visualization of negative refraction. Negative indices were achieved with the use of an ultrathin Au-Si
3
N
4
-Ag waveguide sustaining a surface plasmon polariton mode with antiparallel group and phase velocities. All-angle negative refraction was observed at the interface between this bimetal waveguide and a conventional Ag-Si
3
N
4
-Ag slot waveguide. The results may enable the development of practical negative-index optical designs in the visible regime.
2006: Signaling Breakthroughs of the Year
Authors: Adler Elizabeth M. , Gough Nancy R. , Ray L. Bryan
Published: March 2007

With nominations from leading scientists studying cell signaling, the STKE editors compile a list of the year's most important advances. Signaling breakthroughs included molecules and processes both outside cells and inside cells, from channels in the membrane to chromatin in the nucleus. The nominated research ranged from structural and functional revelations to approaches for the global analysis of signaling pathways. Receptors were highlighted with unexpected proteins functioning as receptors, as well as surprising functions for known receptors. This year also brought new insights into the impact of cell signaling on human physiology and disease.
Are Microbial Swords Really Plowshares?
Authors: Adler Elizabeth M.
Published: March 2007

The production of antibiotics by microorganisms has generally been interpreted as a microbial mechanism for killing off competitors. If this were the case, even suboptimal concentrations of antibiotics that were inadequate to inhibit growth might be expected to reduce the fitness and virulence of bacterial pathogens. Linares
et al
. investigated this hypothesis by exposing
Pseudomonas aeruginosa
, a major opportunistic bacterial pathogen, to concentrations of three antibiotics (tobramycin, tetracycline, and ciprofloxacin) just below those required to visibly decrease bacterial growth and found that subinhibitory concentrations of these antibiotics actually enhanced various adaptive traits. All three antibiotics stimulated biofilm formation. Tobramycin also stimulated swimming and swarming, whereas tetracycline increased the expression of genes associated with type III secretion and enhanced
P. aeruginosa
cytotoxicity toward a macrophage cell line. The authors argue that, aside from the clinical implications, their work suggests that—rather than being used as weapons—antibiotics may be used as intermicrobial signaling molecules involved in regulating the homeostasis of microbial communities.

J. F. Linares, I. Gustafsson, F. Baquero, J. L. Martinez, Antibiotics as intermicrobial signaling agents instead of weapons.
Proc. Natl. Acad. Sci. U.S.A.
103
, 19484-19489 (2006).
[Abstract]
[Full Text]
Cathepsins Sculpt Toes
Authors: Gough Nancy R.
Published: March 2007

Digit formation involves massive programmed cell death. Zuzarte-Luis
et al
. show that in chicken embryo interdigital regions destined for cell death, the abundance of cathepsin D was increased, and in interdigit mesodermal cells, the enzyme transitions from a lysosomal localization to a cytosolic one as the cells begin to undergo cell death. Implantation of a bone morphogenetic protein (BMP) bead onto chicken or mouse embryo limbs resulted in increased expression of the
cathepsin D
gene in areas adjacent to the bead. A similar correlation between
cathepsin B
expression, BMP signaling, and regions destined for programmed cell death was noted. However,
cathepsin L
expression appeared at later stages of digit formation and was not increased by BMP beads. Cell death in the interdigital region was only effectively blocked if cultured limbs were exposed to both pepstatin A (a cathepsin D inhibitor) and a pan-caspase inhibitor. Cultured chicken cells overexpressing cathepsin D exhibited increased cell death, altered morphology, and nuclear translocation of apoptosis-inducing factor (AIF), which suggested that cathepsin D triggers mitochondrial permeabilization. The authors propose that, in tissues that require massive remodeling through cell death, both lysosomal enzymes and caspases contribute to the process.

V. Zuzarte-Luis, J. A. Montero, Y. Kawakami, J. C. Izpisua-Belmonte, J. M. Hurle, Lysosomal cathepsins in embryonic programmed cell death.
Dev. Biol.
301
, 205-217 (2007).
[PubMed]
Asymmetric Turning Mechanisms
Authors: Adler Elizabeth M.
Published: March 2007

Asymmetric Ca
2+
signals inside neuronal growth cones can mediate attractive or repulsive turning. Localized increases in growth cone Ca
2+
concentration that elicit Ca
2+
-induced Ca
2+
release (CICR) are attractive (the growth cone turns toward the side with greater Ca
2+
concentration), whereas signals that do not elicit CICR are repulsive (the growth cone turns away from the side with greater Ca
2+
concentration). Using localized photolysis of caged Ca
2+
to elicit asymmetric increases in Ca
2+
in the growth cones of cultured chick dorsal root ganglion neurons, Tojima
et al
. manipulated CICR pharmacologically or through culture on different substratum to generate attractive or repulsive turning. Attractive Ca
2+
signals led to the microtubule-dependent migration of fluorescently labeled vesicles from the central to the peripheral region of the growth cone on the side with the Ca
2+
increase, whereas repulsive Ca
2+
signals had no effect on vesicle trafficking. The vesicles contained VAMP2 (vesicle-associated membrane protein 2, a SNARE protein implicated in Ca
2+
-dependent

vesicle fusion with the membrane). When vesicles were labeled with a pH-sensitive fluorescent VAMP2 fusion protein, experiments indicated that attractive Ca
2+
signals

stimulated asymmetric VAMP2-mediated exocytosis. Pharmacological blockade of VAMP2-mediated exocytosis blocked turning to attractive Ca
2+
signals or toward attractive cues (nerve growth factor or myelin-associated glycoprotein), but not axon growth or repulsive turning. Thus, the authors conclude that attractive—but not repulsive—growth cone turning depends on asymmetric vesicle trafficking and exocytosis.

T. Tojima, H. Akiyama, R. Itofusa, Y. Li, H. Katayama, A. Miyawaki, H. Kamiguchi, Attractive axon guidance involves asymmetric membrane transport and exocytosis in the growth cone.
Nat. Neurosci.
10
, 58-66 (2007).
[PubMed]
News on Networking
Authors: Ray L. Bryan
Published: March 2007

Analysis of large data sets describing protein interactions is helping to define how networks of protein interactions control cell function. Kim
et al.
analyze an improved data set that includes information on three-dimensional protein structure and protein domains, which allows distinctions to be made between particular interaction domains and clarifies, for example, whether interactions between two proteins containing the same domain with another protein are expected to be mutually exclusive. This analysis restricts the estimated maximal numbers of protein partners (14) compared with previous estimates. The number of interaction interfaces on a protein is a key defining factor in whether a protein is essential for cell function and for its evolutionary rate.

P. M. Kim, L. J. Lu, Y. Xia, M. B. Gerstein, Relating three-dimensional structures to protein networks provides evolutionary insights.
Science
314
, 1938-1941 (2006).
[Abstract]
[Full Text]

T. O. Yeates, M. Beeby, Proteins in a small world.
Science
314
, 1882-1883 (2006).
[Summary]
[Full Text]
Details Define Double Duty
Authors: Vinson Valda
Published: March 2007

Iron regulatory protein 1 (IRP1) is a dual-function protein. With an iron-sulfur cluster bound, it is a cytosolic aconitase enzyme, but without it, IRP1 binds iron-responsive elements (IREs) in messenger RNA and regulates the expression of genes involved in iron transport, storage, and utilization. Walden
et al

.

now describe the structure of IRP1 bound to ferritin H IRE at 2.8 angstrom resolution and compare it with the known structure of cytosolic aconitase. The switch between the two functions is coupled to large-scale domain rearrangements, from a compact structure in the aconitase to an extended structure that interacts with the IRE at two sites. The RNA binding and enzyme active sites overlap with many amino acids that serve different roles in each state.

W. E. Walden, A. I. Selezneva, J. Dupuy, A. Volbeda, J. C. Fontecilla-Camps, E. C. Theil, K. Volz, Structure of dual function iron regulatory protein 1 complexed with ferritin IRE-RNA.
Science
314
, 1903-1908 (2006).
[Abstract]
[Full Text]

T. A. Rouault, If the RNA fits, use it.
Science
314
, 1886-1887 (2006).
[Summary]
[Full Text]
What's in a Vaccine?
Authors: Simpson Stephen
Published: March 2007

After vaccination, the efficiency with which protective antibodies are produced often depends on the presence of an adjuvant, a substance that promotes activation of antibody-producing B cells. It has been anticipated that Toll-like receptors (TLRs) might be major players in mediating the effects of adjuvants. However, Gavin
et al.
now find that the known TLR pathways do not modulate B cell responses, and so adjuvants containing TLR ligands must depend on other properties. Such a revision to thinking about the effects of TLR on B cell responses will likely refocus current thinking about vaccine development.

A. L. Gavin, K. Hoebe, B. Duong, T. Ota, C. Martin, B. Beutler, D. Nemazee, Adjuvant-enhanced antibody responses in the absence of Toll-like receptor signaling.
Science
314
, 1936-1938 (2006).
[Abstract]
[Full Text]
Mapping the c-MYC Oncogene-Induced Pathway to Cell Death
Authors: Ray L. Bryan
Published: March 2007

Cancer is often caused by cells that show not only excessive proliferation but also resistance to apoptosis. Thus, deciphering the signaling pathways that are disrupted in transformed cells that become resistant to apoptosis may provide insights for the control of human cancer. For example, the oncoprotein c-MYC, an important contributor to human tumors, acts both to increase proliferation and to promote cell death. Myc is a transcription factor that can both activate and repress gene transcription and thus influences many potential targets that might contribute to regulation of apoptosis. Patel and McMahon extended earlier studies showing that binding of Myc to another transcription factor, MIZ-1, and inhibition of MIZ-1-dependent transcription were important for promotion of apoptosis by c-MYC. The new work shows that a critical target of MIZ-1 is the antiapoptotic protein BCL2. In cultured human diploid fibroblasts, a form of c-MYC (c-MYCV394D) that fails to interact with MIZ-1 was also defective in inducing apoptosis. Furthermore, if expression of MIZ-1 was reduced in these cells by expression of short hairpin RNA (shRNA), the apoptotic effect of c-MYCV394D was restored, indicating that MIZ-1 is a key target of c-MYC in controlling apoptosis. However, MIZ-1 activates transcription of several hundred genes, and the authors wanted to know which were necessary and/or sufficient to reproduce the effects of MIZ-1 to promote cell survival. A search of the MIZ-1 target genes revealed in microarrays yielded a likely candidate--the gene encoding the antiapoptotic protein BCL2. Indeed, expression of BCL2 was decreased by wild-type c-MYC but not by the c-MYCV394D mutant, and inhibition of expression of BCL2 by shRNA rescued the effect of c-MYCV394D to promote apoptosis. Many earlier studies of mouse models and of human tumor cells have shown that BCL2 and c-MYC appear to work together in promoting cancer. At least in certain cell types, the new results indicate that transcription of the
BCL2
gene is the essential target regulated through c-MYC and MIZ-1, thus providing a mechanistic explanation for the observed cooperation of BCL-2 and c-MYC in tumorigenesis.

J. H. Patel, S. B. McMahon, BCL2 is a downstream effector of MIZ-1 essential for blocking c-MYC-induced apoptosis.
J. Biol. Chem.
282
, 5-13 (2007).
[Abstract]
[Full Text]
Saved from Proteolysis
Authors: Adler Elizabeth M.
Published: March 2007

Terminal erythroid differentiation in response to erythropoietin depends on caspase-3 activation, whereas erythropoietin withdrawal leads to caspase-mediated proteolysis of the transcription factor GATA-1 and apoptosis. Ribeil
et al
. observed that activated caspase-3 colocalized in the nucleus with GATA-1 during erythroid differentiation and wondered how GATA-1 escaped proteolysis. They found that during differentiation, the molecular chaperone Hsp3 (which was expressed constitutively by differentiating human erythroblasts) colocalized in the nucleus with GATA-1, whereas Hsp70 disappeared from the nucleus during erythropoietin starvation. Hsp70 coimmunoprecipitated with GATA-1 from differentiated erythroblasts and protected GATA-1 from caspase-3-mediated cleavage in an in vitro proteolysis assay. Hsp70 knockdown with siRNA led to GATA-1 degradation in differentiating cells as well as to a decrease in the proportion of differentiating cells and an increase in the rate of cell death. Moreover, a caspase-resistant GATA-1 mutant protected hematopoietic cells from the effects on cell maturation and death of siRNA directed against Hsp70. Thus, the authors propose that erythropoietin protects differentiating erythroid cells from apoptosis by promoting nuclear localization of Hsp70, thereby preventing GATA-1 proteolysis.

J.-A. Ribeil, Y. Zermati, J. Vandekerckhove, S. Cathelin, J. Kersual, M. Dussiot, S. Coulon, I. C. Moura, A. Zeuner, T. Kirkegaard-Sørensen, B. Varet, E. Solary, C. Garrido, O. Hermine, Hsp70 regulates erythropoiesis by preventing caspase-3-mediated cleavage of GATA-1.
Nature
445
, 102-105 (2007).
[PubMed]