Caries in the infundibulum of the second upper premolar tooth in the horse

Background  

Swedish equine dental practices have empirically found that the prevalence of infundibular caries as a primary disorder in the first permanent premolar teeth (P2) of the horse upper jaw has increased during the last 10 years. A previously unknown bacterial species, Streptococcus devriesei (CCUG 47155^T), which is related to Streptococcus mutans, has recently been isolated from these carious lesions. To understand the aetiology of caries in horses, it is essential to elucidate the relationship between S. devriesei and P2 infundibular caries.     

Maximum in the stability of the amorphous state in the system water--glycerol--ethanol.

When the proportions of glycerol and ethanol vary for a given water concentration, the stability of the amorphous state of the whole solution in the system water-glycerol-ethanol passes through a maximum. This ternary system may then be much more interesting for cryoprotection than the system water-glycerol-DMSO. The phase transitions on rewarming at several rates after rapid or slow cooling, or after annealing, were observed by calorimetry and the various states between the transitions including the amorphous state were observed by X-ray diffraction. However, this system is much more complicated than the system water-glycerol-DMSO, due to the existence of two ethanol hydrates. Since, beyond a certain ethanol concentration, a first melting occurs before the devitrification, the stability of the amorphous state could no longer be defined by the critical warming rate. It was then defined by the amount of crystals formed on cooling, which was surprisingly reproducible in the present experiments for each cooling rate. The maximum in the stability occurs for rather low ethanol concentrations, which is of interest since ethanol is more toxic that glycerol. The concentration corresponding to the maximum depends on the cooling rate. It occurs at about 20% ($\text{w}\text{w}$) ethanol/(glycerol + ethanol) for the 50 and 55% ($\text{w}\text{w}$) water solutions. It is shifted to 40% ($\text{w}\text{w}$) ethanol/(glycerol + ethanol) for the 60% ($\text{w}\text{w}$) water solutions.     

Role of the mitochondrion in the regulation of protein synthesis in the eucaryote Saccharomyces cerevisiae

Summary Induction of several enzymes is abolished in respiratory deficient strains of Saccharomyces cerevisiae. Such block depends on the integrity of the mitochondrial protein sinthesizing machinery. A model is proposed which is based on a double control of protein synthesis, a negative regulation similar to that described in E. coli and a positive regulation mediated by mitochondria.     

High cancer mortality rates in the elderly in the UK

Introduction: Cancer is largely a disease of older individuals. We compared UK cancer mortality rates with those for other countries to assess progress. Methods: Death details were obtained from the WHO Mortality Database for the UK, the USA and 11 European countries. Mortality rates were calculated for the age groups 55–64, 65–74, 75–84 and ≥85 years. Trends between 1995–97 and 2003–05 were determined. The number of excess cancer deaths in the UK was calculated by applying the age-specific mortality rates observed in other regions to the UK. Results: For all cancers combined, UK rates for 2003–05 in those aged ≥75 years were 11–31% higher than in other regions. From 1995–97 to 2003–05, UK rates decreased by 16–17% in those aged <75 years, but increased by 2% in those ≥85 years compared with decreases of 4–16% for the other geographic areas. More than 14,000 cancer deaths in the UK in those aged ≥75 years would be avoided each year if UK mortality rates were identical to those in the USA. Conclusion: The UK is making poor progress in controlling cancer in older age groups. The gap in mortality rates between the UK and other countries and between old and young in the UK is widening.     

Categorization of the mitochondria-rich cells in the gill epithelium of the freshwater phases in the life cycle of lampreys

The distribution and ultrastructure of the mitochondria-rich (MR) cells in the gills of larval (ammocoetes) and adult lampreys (Petromyzon marinus and Geotria australis) have been studied. One type of MR cell, which is found only in ammocoetes, occurs in groups on and between gill lamellae. Freeze-fracture replicas show that the apical membrane of this ammocoete MR cell contains globular particles. The second type of MR cell, which is present in both ammocoetes and adults in freshwater, is located between lamellae and at the base of the filament. This cell usually occurs singly and is typically intercalated between ammocoete MR cells in larval lampreys and between pavement cells and pavement and chloride cells in adult lampreys. It contains rod-shaped particles in either the apical membrane (subtype A) or, far less frequently, the lateral membrane (subtype B) and in membranes of cytoplasmic vesicles and tubules. These features characterize this intercalated MR cell as a member of a group of MR cells that are also found in urinary epithelia of tetrapods and the amphibian epidermis, where they are involved in H⁺ and HCO₃ ^- secretion. Because this type of MR cell disappears when the young adult lamprey enters the sea and reappears immediately after the fully grown adult re-enters freshwater on its spawning run, it is presumably essential for osmoregulation in freshwater. On the basis of electrophysiological studies on frog skin, it is proposed that the subtype A of the branchial intercalated MR cell of lampreys provides the driving force for the Na⁺ uptake by active H⁺ secretion. By analogy with urinary epithelia, the subtype B cells may exchange Cl^- for HCO₃ ^-.     

Examination of the Intron in the meiosis-specific recombination gene REC114 in Saccharomyces

REC114 is one of 10 genes known to be required for the initiation of meiotic recombination in Saccharomyces cerevisiae. It is transcribed only in meiosis, and our previous sequence analysis suggested the presence of an intron in the 3′ end of the gene. Hypotheses in the literature have suggested, because of its unusual location, either that the putative intron in REC114 is likely to be necessary for expression, or that there may actually be no intron present. This work demonstrates that REC114 does have an intron and is one of only three genes in yeast with introns located in the 3′ end. Furthermore, the 3′ splice site utilized in REC114 is a very rare AAG sequence; only three other genes in yeast use this nonconsensus sequence. The splicing of REC114 does not require MER1, a gene known to be involved in meiosis-specific RNA processing. In fact, an intronless copy of REC114 can complement a null rec114 mutation. Thus, it does not appear that the intron is essential for expression of REC114. Although the intron is not absolutely required for meiotic function, it is conserved in evolution; two other species of yeast contain an intron at the same location in their REC114 genes.     

Variability in the role of the gasbladder in fish audition

The teleost gasbladder is believed to aid in fish audition by transferring pressure components of incoming sound to the inner ears. This idea is primarily based on both anatomical observations of the mechanical connection between the gasbladder and the ear, followed by physiological experiments by various researchers. The gasbladder movement has been modeled mathematically as a pulsating bubble. This study is extending the previous work on fish with a physical coupling of the gasbladder and ear by investigating hearing in two species (the blue gourami Trichogaster trichopterus, and the oyster toadfish Opsanus tau) without a mechanical linkage. An otophysan specialist (the goldfish Carassius auratus) with mechanical coupling, is used as the control. Audiograms were obtained with acoustically evoked potentials (e.g., auditory brainstem response) from intact fish and from the same individuals with their gasbladders deflated. In blue gourami and oyster toadfish, removal of gas did not significantly change thresholds, and evoked potentials had similar waveforms. In goldfish thresholds increased by 33–55 dB (frequency dependent) after deflation, and major changes in evoked potentials were observed. These results suggest that the gasbladder may not serve an auditory enhancement function in teleost fishes that lack mechanical coupling between the gasbladder and the inner ear. Accepted: 28 February 2000     

Apparent violations of the all-or-none law in relation to potassium in the protoplasm

The protoplasm of Nitella forms a thin layer surrounding a large central vacuole filled with sap. At the inner surface of the protoplasm is a non-aqueous layer called Y and at the outer surface is a similar layer called X. At each of these layers there is a potential due to the diffusion of KCl in contact with the layer. We thus have P = P_X + P_Y in which P is the total potential, P_X is the potential at X, and P_Y the potential at Y. We assume that when stimulation occurs P_Y disappears and P_X remains unaltered. The loss of part of the potential therefore involves no violation of the all-or-none law since the Y layer loses all of its potential and the X layer loses nothing. If the concentration of KCl in the external solution and in the sap is known the concentration in the protoplasm can be calculated at each stimulation by measuring the height of the spike.     

Involvement of the narJ and mob gene products in distinct steps in the biosynthesis of the molybdoenzyme nitrate reductase in Escherichia coli

The Escherichia coli mob locus is required for synthesis of active molybdenum cofactor, molybdopterin guanine dinucleotide. The mobB gene is not essential for molybdenum cofactor biosynthesis because a deletion of both mob genes can be fully complemented by just mobA. Inactive nitrate reductase, purified from a mob strain, can be activated in vitro by incubation with protein FA (the mobA gene product), GTP, MgCl₂, and a further protein fraction, factor X. Factor X activity is present in strains that lack MobB, indicating that it is not an essential component of factor X, but over-expression of MobB increases the level of factor X. MobB, therefore, can participate in nitrate reductase activation. The narJ protein is not a component of mature nitrate reductase but narJ mutants cannot express active nitrate reductase A. Extracts from narJ strains are unable to support the in vitro activation of purified mob nitrate reductase: they lack factor X activity. Although the mob gene products are necessary for the biosynthesis of all E. coli molybdoenzymes as a result of their requirement for molybdopterin guanine dinucleotide, NarJ action is specific for nitrate reductase A. The inactive nitrate reductase A derivative in a narJ strain can be activated in vitro following incubation with cell extracts containing the narJ protein. NarJ acts to activate nitrate reductase after molybdenum cofactor biosynthesis is complete.     

Reproduction in Seagrasses: Nature of the Pollen and Receptive Surface of the Stigma in the Hydrocharitaceae

This paper describes the characteristics of the pollen and thereceptive surfaces of the stigmas in the three marine angiospermsincluded in the Hydrocharitaceae. The pollen in Enhalus acoroidesand Thalassia hemprichii is spherical and has an ornamentedexine. An exine layer is not found in Halophila stipulacea wherereniform pollen grains are contained within transparent moniliformtubes. Cytochemical tests show that the pollen wall in the threespecies contains acidic and neutral polysaccharides and acidhydrolase acitivity is detected in the intine of H. stipulaceaand T. hemprichii. In Thalassia, one of the intine enzymes,acid phosphatase, is unambiguously associated with cytoplasmicinclusions. Flowering in Thalassia is coincident with the spring tides andthe pollen is released as a mass suspended in a thecal slimewhich contains approximately 5 per cent by weight carbohydrate,the principal mono-saccharide being mannose. Electrophoreticanalysis of the pollen-free slime shows a single glycoproteincomponent. The stigmas of the three seagrasses are papillate and of the‘dry’ type possessing a continuous protein-aceouspellicle subtended by a cuticle. The stigma pellicle exhibitscytochemically detectable esterase activity and binds the lectinconcanavalin A. Acid phosphatase activity is localized beneaththe cuticle at the tips of the stigma papillae. The discoveries show that the characteristics of the pollenand stigmas in the seagrasses are comparable with those foundin terrestrial flowering plants. The similarity in enzymaticproperites of the pollen wall and stigma pellicle suggests that,intriguingly, a similar mechanism of cuticle erosion might wellfollow compatible pollination both on land and in the sea. Enhalus acoroides, Thalassia hemprichii, Halophila stipulacea, Halophila decipiens, seagrasses pollen wall, stigma surface, hydrolytic enzymes     

A yeast in the stomach of the mouse

Summary The high incidence (100 %) ofTorulopsis pintolopesi in the stomach of the mouse and the absence of any type of inflammatory response show the existance of an adaptation between the yeast and the mouse. This is in agreement with the opinion ofParle that the yeast belongs to the normal flora of the digestive tract. According to our studiesT. pintolopesi is an acidophilic species which is a normal host in the stomach and a transient organism in the intestine.     

Geographic variation in the damselfish-red alga cultivation mutualism in the Indo-West Pacific

Background  

On coral reefs, damselfish defend their territories from invading herbivores and maintain algal turfs, from which they harvest filamentous algae. In southern Japan, intensive weeding of indigestible algae by Stegastes nigricans results in overgrowth by one filamentous alga, Polysiphonia sp. 1. Because this alga is highly susceptible to grazing and is competitively inferior to other algae, it survives only within the protective territories of this fish species, suggesting an obligate mutualism between damselfish and their cultivated alga. The wide distribution of damselfish species through the Indo-Central Pacific raises the question of whether this species-specific mutualism is maintained throughout the geographic range of the fish. To address this question, from all 18 damselfish species we conducted comprehensive surveys of algal flora within their territories throughout the Indo-West Pacific, and identified species of Polysiphonia using morphological examination and gene sequencing data.     

Variations in the Number of the Y Chromosomal Rrna Genes in DROSOPHILA HYDEI

The number of rRNA cistrons is measured by filter saturation hybridization in different stocks of D. hydei, where the wild-type X chromosome has one nucleolus organizer (NO) and the wild-type Y has two separated NO's. (see PDF) females having no X chromosomal NO show an rDNA content exceeding that of a Y chromosome. An even greater increase in the rRNA cistron number is measured in two translocation stocks where the (see PDF) is combined with one half of a Y and, therefore, each stock contains only one of the two Y chromosomal NO's. But when the same Y fragments are brought together with a wild-type X chromosome they lose about one-half of their rRNA cistrons within one generation. Males with two complementary Y fragments but having no X chromosomal NO show a considerably higher rDNA content than the (see PDF) females, although both are equal in respect of their NO number. Consideration is given to related phenomena in Drosophila melanogaster.     

On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Phylogeny of Itaquasconinae in the light of the evolution of the flexible pharyngeal tube in Tardigrada

The family Hypsibiidae comprises four subfamilies, among which Itaquasconinae are the most abundant in genera. Although being morphologically diverse and cosmopolitan, itaquasconins are scarcely reported and their taxonomy is entangled. Here, we present a phylogeny based on three DNA markers and morphological clues obtained from a detailed scanning electron microscopy analysis of bucco-pharyngeal apparatuses of 25 species representing seven genera. Our study revealed that (a) the polyphyletic Adropion consists of at least three evolutionary lineages, with Guidettion gen. nov. being the sister group of all remaining itaquasconins; (b) stylet supports were independently lost in Astatumen and Insulobius gen. nov.; (c) pharyngeal tube annulation can be divided into two general types, simple and complex, and is stable at the genus level, but being homoplasious (similarly to the apophyses for the insertion of stylet muscles and the shape of the claw bases), it is not useful in inferring phyletic relationships within the subfamily; and (d) Astatumen and Platicrista contain numerous similar species, challenging the current taxonomic classification; moreover, (e) three new taxa are proposed to accommodate the newly recognised lineages: Guidettion gen. nov. (the former Adropion prorsirostre group), Insulobius gen. nov. (for a new Malayan species with a mixture of Astatumen and Itaquascon traits), and Raribius gen. nov. (former Itaquascon spp. with an elongated and narrowed pharyngeal tube terminating with a spherical pharynx). The simple type of annulation is synapomorphic to Hypsibiidae, with single reversals to the uniform buccal tube in Parascon (Itaquasconinae) and in Hypsibiinae. The pharyngeal tube evolved convergently several times, and is of different character in classes Heterotardigrada and Eutardigrada.     

Phosphorylation is Involved in the Regulation of the Taurine Influx Via the β-system in Ehrlich Ascites Tumor Cells

The role of 3′,5′-cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), protein kinase C (PKC) and phosphatases in the regulation of the taurine influx via the β-system in Ehrlich ascites tumor cells has been investigated. The taurine uptake by the β-system in Ehrlich cells is inhibited when PKC is activated by phorbol 12-myristate 13-acetate (PMA) and when protein phosphatases are inhibited by calyculin A (CLA). On the other hand, taurine uptake by the β-system is stimulated by an increased level of cAMP or following addition of N⁶,2′-O-dibutyryl-3′,5′-cyclic adenosine monophosphate (dbcAMP). The effect of dbcAMP is partially blocked by addition of the protein kinase inhibitor H-89, and suppressed in the presence of CLA. It is proposed that the β-system in the Ehrlich cells exists in three states of activity: State I, where a PKC phosphorylation site on the transporter or on a regulator is phosphorylated and transport activity is low. State II, where the PKC phosphorylation site is dephosphorylated and transport activity is normal. State III, representing a state with high transport activity, induced by an elevated cellular cAMP level. Apparently, cAMP preferentially stimulates taurine transport when the β-system is in State II. Received: 8 September/Revised: 9 November 1995     

Anonymous communications in the Internet

With the growth and acceptance of the Internet, there has been increased interest in maintaining anonymity in the network. By using traffic analysis, it is possible to infer who is talking to whom over the Internet. We present a novel approach to hide the senders and the receivers of messages. Routes are chosen and frames traverse these routes. Each frame consists of a token and a node can send a message through a frame only when the corresponding token is free. The advantage of our protocol is that it poses limited bandwidth overhead when there is at least some traffic, while posing minimal bandwidth overhead when there is no traffic at all.

EpCAM expression in the prostate cancer makes the difference in the response to growth factors

Introduction

Epithelial cell adhesion molecule (EpCAM) is expressed in tumors with an epithelial cell of origin, in a heterogeneous manner. Prostate cancer stem-like cells highly express EpCAM. However, little is known about how EpCAM is involved in the ability of cells to adapt to micro-environmental changes in available growth factors, which is one of the essential biological phenotypes of cancer stem-like cells (CSCs).

Methods

EpCAM-high and EpCAM-low subpopulations of cells were established from the prostate cancer cell line PC-3. Signal transductions in response to serum starvation, and on the exposure to EGF ligand or the specific inhibitor were analyzed in terms. Furthermore, we analyzed the expression level of amino acid transporters which contribute to the activation of mTOR signal between the two subgroups.

Results

EpCAM-high and EpCAM-low PC-3 subpopulations showed markedly different responses to serum starvation. EpCAM expression was positively correlated with activation of the mTOR and epithelial growth factor receptor (EGFR) signaling pathways. Furthermore, AMP-activated protein kinase (AMPK) was gradually de-activated in EpCAM-low PC-3 cells in the absence of serum.

Conclusions

EpCAM regulates the AMPK signaling pathway, essential for the response to growth factors characterized by EGF. LAT1, the amino acid transporter stabilized at the cellular membrane by EpCAM, is likely to be responsible for the difference in the susceptibility to EGF between EpCAM-high and EpCAM-low PC-3 cells.