Capillary Feeding Research Articles

Glass capillary tube feeding: a method for infecting nymphal Ixodes scapularis (Acari: Ixodidae) with the lyme disease spirochete Borrelia burgdorferi.

We evaluated an artificial capillary feeding method to infect nymphal Ixodes scapularis (Say) ticks with Borrelia burgdoeferi, the causative agent of Lyme disease. Thirty to 70% of the nymphs were infected after feeding for 2.5 h from glass capillary tubes filled with a solution of spirochetes. Capillary infection was stable and persisted in the nymphs for at least 10 d after feeding. Capillary feeding also maintained natural vector competence patterns because I. scapularis ticks acquired infection unlike Dermacentor variablis (Say), which did not become infected. Capillary infected I. scapularis nymphs were capable of transmitting the infection to naive mice although not as efficiently as naturally infected nymphs. The capillary infection method is convenient and is a better alternative to syringe inoculation as a means of infecting animals with B. burgdorferi.

Expression of defensin-like peptides in tick hemolymph and midgut in response to challenge with Borrelia burgdorferi, Escherichia coli and Bacillus subtilis.

Challenge of Dermacentor variabilis by hemocoel injection with Borrelia burgdorferi but not Bacillus subtilis or Escherichia coli provoked secretion of two low molecular weight peptides into the hemolymph plasma; the lower band co-migrated with a band previously identified as varisin (a tick defensin). These findings are consistent with reports that D. variabilis controls B. burgdorferi but not B. subtilis or E. coli by defensin-dependent bacteriolysis. Challenge of the tick midgut by capillary artificial feeding with bacteria also provoked expression of multiple low molecular weight peptides. In this case, however, all three bacteria elicited the response. Two bands, including the defensin-like peptide were expressed following challenge with B. subtilis and E. coli, but only the upper band following challenge with B. burgdorferi. Although they appeared intact, these spirochetes were no longer viable suggesting that borreliae in the midgut are controlled by a different method than the lytic response of the D. variabilis hemolymph. DD-RT-PCR revealed multiple mRNAs in the midgut of D. variabilis following challenge with B. burgdorferi, E. coli and Rickettsia montana. Although their identification remains to be determined, the large number of genes expressed in response to bacterial challenge presents intriguing possibilities for explaining the ability of the tick midgut to destroy invading microbes at the cellular level.

Infection and transovarial transmission of rickettsiae in Dermacentor variabilis ticks acquired by artificial feeding.

In this study we examined the efficiency of an in vitro feeding technique using glass microcapillaries as a method of establishing rickettsiae-infected lines of ticks. To quantify the volume ingested by ticks during microcapillary feeding, the incorporation of radiolabeled amino acids in tick gut and hemolymph was calculated. Fifteen of 18 ticks consumed between 0.06 and 6.77 microl. However, ingestion of fluid was not correlated to weight gain during capillary feeding. Uninfected and partially fed laboratory-reared female Dermacentor variabilis ticks were exposed to either Rickettsia montana- or Rickettsia rhipicephali-infected Vero cells via microcapillary tubes, returned to rabbit hosts, and allowed to feed to repletion. All tissues collected from ticks allowed to feed overnight on rickettsiae-infected fluids were found to be infected when examined by IFA. When rickettsiae-infected and uninfected capillary-fed ticks were allowed to feed to repletion and lay eggs, no significant differences in mean engorgement weight or fecundity was observed. When we assessed the efficiency of transovarial transmission of rickettsiae by ticks that imbibed rickettsiae-infected cells by polymerase chain reaction (PCR) and IFA, infection was detected by PCR in the eggs from 85% of the ticks exposed to R. montana and 69% of the ticks exposed to R. rhipicephali. Rickettsial genes were not amplified in samples of the uninfected controls. Examination by IFA of egg samples from females exposed to rickettsiae-infected cells identified rickettsiae in 100% of the samples tested, while the uninfected controls were negative.

Amblyomma americanum: Specific Uptake of Immunoglobulins into Tick Hemolymph during Feeding

Jasinskas, A., Jaworski, D. C., and Barbour, A. G. 2000. Amblyomma americanum: Specific uptake of immunoglobulins into tick hemolymph during feeding. Experimental Parasitology96, 213–221. The passage of immunoglobulins in the blood meal into hemolymph prompts development of vaccines against internal antigens of ticks, but little is known about kinetics and specificity of the immunoglobulin uptake. We used capillary feeding of adult Amblyomma americanum hard ticks to introduce compounds into the midgut and then examined the hemolymph after various times for their presence and concentration. Immunoglobulins of different sources, albumin, choramphenicol acetyltransferase, inulin, and mannitol were labeled with 125I, 14C, or biotin. With the exception of the carbohydrate inulin, all the compounds entered the hemolymph of tick during capillary feeding. The small molecule mannitol had the highest rate of entry at 9% after 6 h. Among proteins, the entry of immunoglobulin G (IgG) of different species into the hemolymph was greater at 6% after 6 h than for the smaller proteins albumin or choramphenicol acetyltransferase at 1 and 3%, respectively. The entry of denatured IgG was equal to that of nondenatured protein. There was no evidence of degradation of the IgG or of its binding to cells once it entered the hemolymph. A monoclonal IgG antibody labeled with biotin entered the hemolymph and retained its ability to bind to its specific antigen in an immunoassay. Although different proteins entered the hemolymph after capillary feeding, there was evidence of a specific mechanism for immunoglobulin uptake.

Production of pheromones by artificially fed males of the tick Amblyomma maculatum (Acari: Ixodidae).

Aggregation-attachment pheromones are produced only by male ticks of the genus Amblyomma that have imbibed blood for at least 8 d from their mammalian hosts. This report demonstrates that production and release of aggregation-attachment pheromones by Amblyomma maculatum (Koch) males can be induced in vitro by using nonblood media, artificially introduced through capillary tubes, into the male ticks. The presence of these pheromones is demonstrated by using both biological observations on bovine hosts and in vitro experimentation with petri dishes. The attraction of unfed female ticks to the artificially fed males (using the petri dish method) was significantly higher (P < 0.001) than the attraction of unfed females to unfed males. Similarly, attraction and attachment were recorded on bovine hosts. Only 62.8 +/- 17.5% of the females released attached to the bovine host. Of these, 61.9 +/- 19.37% attached around artificially fed males that were placed on the bovine 24 h earlier. This percentage did not differ significantly from the 81.4 +/- 7.1% of the total that attached around males that fed naturally for 8 d. In comparison, only 33.3 +/- 21.9% of the total number of females placed on the host did so after being fed 1 d (control group). The possibility of using capillary feeding as a new tool for investigating the physiology and reproductive behavior of blood-sucking arthropods is discussed.

Arterial chemoembolization for hepatocellular carcinoma.

AIM:To study the therapeutic effects of transcatheter arterial three-segment chemoembolization for hepatocellular carcinoma (HCC).METHODS: According to the anatomy of vessels, the tumor capillary networks, muscular arterioles and feeding arteries were successively occluded using lipiodol ultra-fluid (LUF), sinobufagin microsphere (SBMs) and particles of gelatin sponge (PGS). In this series of 80 cases, therapeutic effects were evaluated in 76 cases.RESULTS: There were 22 cases (28.9%) with partial response and 41 (53.9%) with minor response in the 76 evaluated patients. The 6-month, 1-year, 2-year and 3-year survival rates were 97.4%, 86.8%, 46.1% and 27.6% respectively.CONCLUSION: This regimen was a rational chemoembolization method for HCC patients.

Fabrication of near-net-shaped sapphire domes by noncapillary shaping method

Near-net-shaped sapphire domes were successfully grown directly from the melt by novel noncapillary shaping method (NCS method). NCS combines EFG capillary feeding and bulk growth sequentially. The obtained blanks up to 80 mm diameter demonstrated a high crystalline and optical quality. Several near-net-shaped sapphire domes were grown in the course of one growth process.

A double-die modification of micro-pulling-down method for in situ clad/core doping of fiber crystal

A novel technique for single-crystal fibers cladding immediately in the course of the growth process based on the micro-pulling-down (μ-PD) method has been proposed and verified. The principle of the double-die-μPD implies that the capillary nozzle provides capillary feeding to the growing fiber simultaneously from the inner pipe channel with undoped melt and from the outer surface with doped melt. The menisci shape, melt flow outside the nozzle, control of the doped/undoped melt ratio and process stability are discussed in terms of capillarity. Examples of practical crucible design are discussed in connection with radial dopant distribution. Mn-doped lithium niobate fiber, 0.5 and 0.7 mm in diameter, having 40–60 μm doped outer area were grown successfully.

Difference in vector competence of two species of sympatric ticks, Amblyomma variegatum and Rhipicephalus appendiculatus, for Dugbe virus (Nairovirus, Bunyaviridae)

Amblyomma variegatum was shown to be a competent vector of Dugbe (DUG) virus whereas Rhipicephalus appendiculatus was not. When DUG virus was taken up orally by A. variegatum nymphs, during capillary feeding, the virus replicated and persisted through moulting to the following adult stage. In contrast, although DUG virus replicated in capillary fed R. appendiculatus nymphs, the virus did not persist trans-stadially into the adult stage. If the oral route of infection was by-passed by direct inoculation into the haemocoel, DUG virus replicated and survived trans-stadially in both tick species, and was subsequently transmitted during feeding. The different responses of R. appendiculatus to oral and intra-coelomic routes suggest that DUG virus is able to infect the gut of this tick species, but that release of the virus from the gut is inhibited.

Transmission and in Vitro Excretion of Bluetongue Virus Serotype 1 by Inoculated Culicoides Brevitarsis (Diptera: Ceratopogonidae)

Simple equipment for intrathoracic inoculation of biting midges and mosquitoes is described. The inoculating needle is fitted into a modified disposable syringe, which is connected to a small air pump. By alternately attaching the air line to the intake and exhaust ports of the pump, inoculum can be taken up or expelled with fingertip control. Insects on an entomological cold table are inoculated under a dissecting microscope. An in vitro technique using capillary tube feeding to demonstrate excretion of virus in biting midge saliva is also described. Culicoides brevitarsis midges inoculated with the CSIRO 156 strain of bluetongue virus serotype 1 and held for 13 days at 20 °C transmitted the virus to a sheep; this is the first experimental transmission of any arbovirus by C. brevitarsis . The infection rate of the midges was 100%. By using the capillary feeding technique with the inoculated midges that fed on the sheep, virus excretion rates of up to 53% were recorded. The capillary feeding technique with biting midges is an economical method of determining virus transmission rates without the use of laboratory animals.

Mechanical determinants of nectar feeding strategy in hummingbirds: energetics, tongue morphology, and licking behavior.

To explore the mechanical determinants of feeding strategies for nectar feeders, we develop a fluid dynamical and behavioral model describing the mechanics and energetics of capillary feeding in hummingbirds. Behavioral and morphological data for Calypte and Archilochus are used to test and illustrate this model. We emphasize the important differences between capillary and suction mechanisms of fluid feeding. Model predictions of nectar intake rates and nectar volumes per lick are consistent with observed values for Calypte anna. The optimal nectar concentration maximizing rate of energy intake depends on tongue morphology and licking behavior. For hummingbirds exhibiting optimal licking behavior, the optimal nectar concentration is 35-40% sucrose for feeding on large nectar volumes. For small nectar volumes, the optimal concentration is 20-25%. The model also identifies certain tongue morphologies and licking frequencies maximizing energy intake, that are consistent with available observations on licking behavior and tongue design in nectar feeding birds. These predictions differ qualitatively from previous results for suction feeding in butterflies.The model predicts that there is a critical food canal radius above which suction feeding is superior to capillary feeding in maximizing the rate of energy intake; the tongues of most hummingbirds and sunbirds fall above this critical radius. The development of suction feeding by nectarivorous birds may be constrained by the elastic properties of their flexible tongues. Our results show that, in terms of morphology, scaling, and energetics, different mechanisms of feeding on the same food resource can lead to qualitatively different predictions about optimal design and feeding strategies.

Growth of GaAs 1 - xP x bulk crystals with homogeneous composition

A solution growth method was developed to obtain highly homogeneous GaAs 1 - xP x bulk crystals by a modified traveling solvent technique in a closed tube. The phosphorus source was isolated from the gallium solution and the arsenic source by a quartz plate with a capillary tube feeding through it. The capillary tube served to feed a constant phosphorus vapor to the solution. Arsenic and phosphorus were dissolved into the gallium solution at a high temperature from a mixed vapor whose composition was kept constant. This arsenic and phosphorus then crystallized as GaAs 1 - xP x in the lower-temperature portion of the solution. GaAs 1 - xP x ingots grown by this system were generally about 20 mm in diameter, 20–28 mm in length and 0.1–0.8 in composition x. X-ray analysis showed that the bulk crystals were uniform within 0.1 mole fraction.

A thermocouple psychrometer and its use for the measurement of water vapour pressure near the earth's surface

A thermocouple psychrometer with constantan-manganin junctions as dry and wet bulb sensors is described. The wet bulb is formed by winding a cotton thread around one of the two thermocouples. The water is supplied by capillary feed from a reservoir mounted beneath the perspex frame which supports the two wires.

Electronic recording of the mosquito bite

An electronic device was developed that records the probing, penetration, salivation, engorgement, and withdrawal of a mosquito in relation to its host. Each act is distinct and can be separately recognized in the recording of a single mosquito bite. The chart recordings were correlated with the physiological events taking place within the mosquito during engorgement and salivation. The characteristics of the recorded pattern as well as the time of engorgement were interpreted in terms of capillary and pool feeding.

A compact cathode-ray tube gas chromatograph

A compact cathode-ray tube display gas chromatograph has been constructed for the routine analysis of anaesthetic vapours or similar volatile materials. The analysis is performed by a stainless-steel capillary column feeding into a micro-argon detector. The chromatogram is displayed on a six inch square long persistence cathode-ray tube. A pneumatic gain control and a separate timing channel are provided. The instrument would be of use, with suitable modifications, in industrial and research applications for the rapid analysis of vapour mixtures. The instrument is compact and portable and permanent recording can be made if desired.

Über fokussierenden Ionenaustausch VI. Apparatur zur präparativen Trennung von Metallionen (und anderen Elektrolyten)

AbstractAn apparatus for continuous separation of metal ions by focusing ion exchange has to provide (a) a homogeneous flow of suitable electrolytes normal to an electrical field, (b) efficient cooling devices, (c) feeding and withdrawal systems allowing constant and adjustable liquid‐flows. The first requirement has been solved by a system of channels, separated from each other by ion‐permeable diaphragmas and of such a size that internal convection currents produced by temperature gradients are viscosely damped. Thin glass plates are forming the separation unit and allow a maximum heatflow of 2 kW. Capillary feeding and withdrawal lines under adjustable hydrostatic or aspirator‐pressures give a reliable flow‐pattern. Typical separations with Cu2+/Co2+ and Cu2+/UO22+/Sr2+ model‐mixtures are described in detail. The apparatus is suitable for macro‐preparative electrophoresis and offers advantages in comparison with recently reported devices for similar purposes.

Observations on Pool and Capillary Feeding in Aedes aegypti (L.)

Gordon and Lumsden1, in a classical paper, first directed attention to the fact that mosquitoes take up blood either directly from a capillary or from a pool formed in the tissues by the leakage of blood from a capillary previously lacerated by the mosquito's proboscis. The former method was termed ‘capillary feeding’ and the latter ‘pool feeding’. It was also noted that, when a mosquito fed from a capillary, engorgement took about three minutes as compared with as long as ten minutes when the blood was taken by pool feeding. Attention was also directed to the significance of the two methods of feeding in relation to the taking up and deposition of pathogens by mosquitoes. These experiments were performed on the frog's web, using Aedes aegypti (L.), and were criticized2 on the grounds that the mechanism of feeding might be very different in mammalian tissues. Recently, Griffiths and Gordon3 developed a new technique for making observations on mosquitoes while they fed on the mouse's ear. Using this technique it was possible to show, by direct observation on living mammalian tissue, that no essential difference existed between the method used by mosquitoes while feeding on batrachian and mammalian tissues.