Completion Of Feeding Research Articles

Unexpected failure of Ixodes scapularis nymphs to transmit a North American Borrelia bissettiae strain

Globally, the Borrelia burgdorferi (sensu lato) complex comprises more than 21 species of spirochetes. Although the USA is home to a diverse fauna of Lyme disease group Borrelia species, only two are considered responsible for human clinical disease: Borrelia burgdorferi (sensu stricto) and Borrelia mayonii. However, evidence has implicated additional B. burgdorferi (s.l.) species in human illness elsewhere. While much research has focused on the B. burgdorferi (s.s.)-tick interface, tick vectors for most of the other North American Lyme disease group Borrelia species remain experimentally unconfirmed. In this report we document the ability of Ixodes scapularis to acquire but not transmit a single strain of Borrelia bissettiae, a potential human pathogen, in a murine infection model. Pathogen-free I. scapularis larvae were allowed to feed on mice with disseminated B. burgdorferi (s.s.) or B. bissettiae infections. Molted infected nymphs were then allowed to feed on naïve mice to assess transmission to a susceptible host through spirochete culture and qPCR throughout in ticks collected at various developmental stages (fed larvae and nymphs, molted nymphs, and adults). In this study, similar proportions of I. scapularis larvae acquired B. bissettiae and B. burgdorferi (s.s.) but transstadial passage to the nymphal stage was less effective for B. bissettiae. Furthermore, B. bissettiae-infected nymphs did not transmit B. bissettiae infection to naïve susceptible mice as determined by tissue culture and serology. In the tick, B. bissettiae spirochete levels slightly increased from fed larvae to molted and then fed nymphs, yet the bacteria were absent in molted adults. Moreover, in contrast to B. burgdorferi (s.s.), B. bissettiae failed to exponentially increase in upon completion of feeding in our transmission experiment. In this specific model, I. scapularis was unable to support B. bissettiae throughout its life-cycle, and while live spirochetes were detected in B. bissettiae-infected ticks fed on naïve mice, there was no evidence of murine infection. These data question the vector competence of Ixodes scapularis for B. bissettiae. More importantly, this specific B. bissettiae-I. scapularis model may provide a tool for researchers to delineate details on mechanisms involved in Borrelia-tick compatibility.

Ultrastructure of the intestinal system in unfed larvae of Limnesia maculata (O.F. Müller, 1776) (Acariformes, Limnesiidae)

The intestinal system of unfed fresh-water mite larvae Limnesia maculata (O.F. Müller, 1776) (Acariformes, Limnesiidae) has been studied with transmission electron microscopy. The intestinal system is composed of the foregut, including the pharynx and the esophagus, the sac-like blind midgut and the excretory organ. The pharynx begins with the mouth covered by the labrum. The pharynx runs along the bottom of the gnathosoma and shows ventral dilators. No valves are expressed between the pharynx and the esophagus. The esophagus possesses strongly plicate walls and, before entering the midgut, passes through the brain. The sac-like midgut does not reveal a well-pronounced lumen, developed epithelium and separate lobes. It consists of the two cell types of endoderm origin mixed in the midgut volume. The first type – the vacuolated cells – does not possess Golgi bodies and lysosomal apparatus and shows electron-lucent vacuoles with a granular inclusion inside. These cells apparently do not take part in digestion of the embryonic yolk. The second type – the non-vacuolated cells – shows both, a well developed Golgi complex and large heterolysosomes, and obviously digests the embryonic yolk. Consequently, they may be attributed as specialized vitellophages. Nevertheless, both cell types may take part in formation of the definitive midgut epithelium. The sac-like thin-walled excretory organ is strongly dilated and contains the embryonic wastes in the form of electron-dense globules and birefringent particles. No muscle envelope surrounds the excretory organ. The embryonic wastes together with wastes accumulated during feeding may be evacuated from the organ only after completion of feeding. The excretory canal on this developmental stage is not connected with the excretory organ. It opens to the outside with a simple slit-like excretory pore. Before feeding, larvae have to pass the process of the post-molt development before their midgut would be ready to receive nutrients.

The investigation of alfaalfa effect on the activity of superoxide dismutase in chicken meat in dependence on time storage

This study was conducted in order to monitor the effect of adding lucerne meal to chicken feed mixtures. The experiment was conducted at the Department Food Hygiene and Safety, Faculty of Biotechnology and Food Science, Slovak University of Agriculture in Nitra. Chickens for meat production - final type Cobb 500 were used in the experiment. Chickens were placed in boxes all together for one group at the beginning of the experiment and from 14 days of age chickens were divided individually into floor enriched cages. Feeding of chickens lasted 38 days. The experiment was carried out without sex segregation. For the production of a feed composition was used alfalfa (Medicago sativa) as lucerne meal, which was added to the feed at a rate of 4%, namely: starter (HYD-01), growth (HYD-02) and final (HYD-03). The control group did not include the addition of lucerne meal. Chickens were fed ad libitum. Chickens were slaughtered after completion of feeding and the meat samples were taken for analysis. The collected samples were stored at -18 °C. Collected samples of meat were analyzed after slaughter chickens at time intervals of 6, 12 and 18 months. In the experiment was monitored the content of supeoxid dismutase in the chicken meat depending on the length of storage time. Superoxide dismutase content was increasing by storage time, while there were some statistically significant differences between groups.

Feeding of two species of Scydmaeninae "hole scrapers", Cephennium majus and C. ruthenum (Coleoptera: Staphylinidae), on oribatid mites

Prey preferences and feeding-related behaviour of two Central European species of Scydmaeninae, Cephennium majus and Cephennium ruthenum, were studied under laboratory conditions. These beetles capture mites by using unique premental suckers and then penetrate the prey's cuticle by slowly scraping a hole with their short mandibles. A mechanism for interlocking the sides of beetle's labrum with closed mandibles was discovered, confirming that the predator's mouthparts can be tightly sealed around the penetration site, which enables them to inject digestive juices and ingest liquefied tissues of the prey through a tiny hole. The feeding behaviour of Cephennium can be divided into three phases: (i) attack and stabilization of the attachment site (4-5 min); (ii) penetration of the mite's cuticle (ca. 40 min); and (iii) feeding (several hours). Results of prey choice experiments using over 1200 identified mites belonging to 23 families of Oribatida (55 species) and 6 families of Mesostigmata (9 species) demonstrated that C. majus feeds mostly on members of the Oribatida: Phthiracaridae (72.07% of offered phthiracarids, 26.7% of eaten oribatids), Ceratozetidae (100% and 24.7%, respectively), Achipteriidae (95.59% and 21.7%) and Liacaridae (61.97% and 14.7%); C. ruthenum fed mostly on Phthiracaridae (48.68% and 41.6%), Achipteriidae (37.29% and 24.7%) and Ceratozetidae (82.35% and 15.7%). The entire feeding behaviour from attack to completion of feeding in C. majus took 2.00-10.37 h when eating oribatids ranging in body length from 0.34 to 0.70 mm. Interestingly, it took much longer for C. majus to kill ptyctimous Phthiracarus, body length 0.39-0.45 mm, than any non-ptyctimous oribatids, including the much larger (0.64-0.70 mm) Chamobates subglobulus. The two species of Cephennium differed greatly in their preference for eating Liacaridae due to their large size, which was acceptable for the larger C. majus, but at the edge of acceptability for the smaller C. ruthenum. Comparative analysis of mites eaten by all the studied species of Scydmaeninae resulted in a preliminary identification of morphological types of Oribatida acceptable and non-acceptable for ant-like stone beetles. The most readily accepted oribatids are typically subglobose, with a rigid cuticle, smooth or only shallowly and finely microreticulate surface of the idiosoma, covered with sparse setae or nearly asetose and with short or moderately long legs. In contrast, rejected mites have one or a combination of the following characters: body flattened, not subglobose; the cuticle relatively soft; idiosoma deeply sculptured or coarsely reticulate; legs long and spiny; the body covered with a protective crust of soil particles. Crotonioidea, Carabodidae, Damaeidae and Hermanniellidae seem to be particularly well-protected against scydmaenine predators.

Utilization of dipeptide/protein based diets in larval and juvenile Koi carp – post-prandial free amino acid levels

We have shown previously that diets in which the nitrogen portion is based on synthetic dipeptides (PP) resulted in weight gain by rainbow trout alevins when free amino acid (FAA) based diets did not. However, the protein-based diet used as a control in the previous study resulted in a significantly better performance of fish than peptide- or FAA based diet fed fish. Therefore, the objectives of our study were (i) to test how stomachless fish respond to peptide-based diets, (ii) to evaluate PP and protein-PP mixture diets and (iii) to examine if post-prandial response to FAA concentrations in the fish body can be used as an indicator of the availability of dietary amino acid sources. The first experiment was conducted with a 4-day old Koi carp (Cyprinus carpio) larvae and included groups fed a casein-gelatin (CG) based diet, a commercial diet and live Artemia nauplii. In the second experiment, fish fed live Artemia for 3 weeks (69 +/- 12 mg) were placed in glass aquaria in triplicate per dietary treatment. Four diets provided equivalent amounts of nitrogen in the form of a CG, a PP, a 50% PP and 50% CG (PP50) mix and as FAA. Fish were fed at 1 and 3 h intervals, and the survival and growth were monitored during the second and third weeks of experiments 1 and 2 respectively. Following the completion of feeding, juvenile carp were sampled prior to feeding and 3 h after a meal. Whole body FAA analyses were carried out. We observed marginal suitability of the CG diet for larval Koi carp, as earlier indicated in common carp. Juvenile Koi carp fed the CG diet achieved 236 +/- 19 mg, whereas PP50, PP and FAA diet fed fish grew to 140 +/- 37, 70 +/- 8 and 73 +/- 5 mg respectively. Free amino acids in the fish body, and in particular indispensable amino acids (IDAA), were excellent indicators of dietary availability. The present experiment shows that a dietary 1:1 ratio of protein to synthetic PPs results in better growth, survival and whole body IDAA concentrations in relation to FAA- and PP-based diets confirming earlier reports on the use of synthetic PP-based diets, although this diet does not match the performance of complete protein, CG-based diet.

Changes in gut content and composition of juvenile Artemia after oil enrichment and during starvation

Some larval crustacean tear Artemia to pieces before ingestion. This results in the loss of gut contents, which may partly negate the benefits of enrichment with essential fatty acids (EFA). Therefore, the influence of gut content on the lipid composition of juvenile Artemia (5 days old) was examined by starvation alone, or starvation with forced gut evacuation using 20–30-μm plastic beads. Artemia gut content, at 3 and 6 h after the completion of feeding, did not contribute significantly to the total lipid or fatty acid profiles of the Artemia. Artemia subjected to starvation alone (without beads) failed to evacuate their gut over the 6-h starvation period, suggesting they require the intake of suitable-sized particulate matter to undertake gut evacuation. To assess the uptake of EFA in metanauplii (day 2) and juveniles, an enrichment diet containing high levels of arachidonic acid [AA, 20:4 n−6] and eicosapentaenoic acid [EPA, 20:5 n−3] was compared to a basal oat-based diet and a commercial oil emulsion high in docosahexaenoic acid [DHA, 22:6 n−3]. Both AA and EPA were increased in juvenile Artemia within a 24-h enrichment period at a rate proportional to their inclusion in the enrichment, while DHA was incorporated to a lesser degree. For all three EFA, the percentage loss during the 6-h starvation was small, but was greater for DHA than EPA or AA. Juvenile Artemia, a life stage seldom used in feeding regimes, have the ability to assume the AA and EPA profile of their dietary source. The ability to produce a larger food source with a non-traditional fatty acid profile may be valuable for a number of larval crustacean and fish species.

Slow infusion feedings enhance duodenal motor responses and gastric emptying in preterm infants

It is unknown whether it is better to feed preterm infants intragastrically by bolus or continuous infusion. This study compared the effect of 2 feeding rates on antral and duodenal motor responses and gastric emptying. Continuous perfusion manometry with a low-compliance machine was performed in 22 infants given feedings at 2 infusion rates. Gastric emptying was also assessed by using a dye-dilution technique to determine whether changes in motor response were reflected by changes in function. The number of antral contractions with both feeding rates decreased from that seen during fasting. Duodenal motor responses increased when infants were fed by slow infusion and decreased when they were fed by rapid infusion. Infants emptied 12 mL/kg of a 20-mL/kg feeding by 20 min after completion of the feeding given by slow infusion concomitantly with the increase in duodenal motor activity but only 8 mL/kg by 20 min after completion of the bolus feeding, when duodenal motor activity decreased (P < 0.01). Two hours after completion of the feeding, volumes remaining in the stomach after slow infusion were one-ninth those remaining after bolus feeding. When preterm infants are fed by slow infusion over 120 min, their duodenal motor responses are more like those observed in adults and their gastric contents are emptied faster and more completely than when they are fed with a rapid bolus. Am J Clin Nutr 1998;68:103–8.

Growth and migration of Borrelia burgdorferi in Ixodes ticks during blood feeding.

We have studied the growth of Borrelia burgdorferi in nymphal ticks (Ixodes scapularis) feeding on mice using confocal fluorescence microscopy to follow the distribution of spirochetes. In starved nymphs, the bacteria were only detected in the midgut and each nymph had a mean of 496 spirochetes. Upon attachment of nymphs to the host, the bacteria grew with a doubling time close to 4 hr and reached a mean of 7,848 spirochetes per nymph 15 hr after attachment. During this initial period (36 hr) of rapid growth, the bacteria appeared to be restricted to the gut, but after 48 hr, the spirochetes had disseminated to the salivary glands in the majority of nymphs examined. Thus, a critical event that allows the spirochetes to disseminate and infect the salivary glands takes place 36-48 hr after attachment. A maximum number of 166,575 spirochetes per nymph was noted 72 hr after attachment. Soon after completion of feeding and detachment from the host (96 hr), the mean number of spirochetes decreased to 95,410 per nymph and the spirochetes appeared to be cleared from organs other than the midgut. Thus, dissemination of spirochetes within the vector appears to be a transient phenomenon. These results provide strong evidence in favor of a salivary route of disease transmission while also demonstrating the utility of confocal microscopy to study vector-pathogen interactions in general.

PHAGOTROPHY IN THE FRESHWATER, PHOTOSYNTHETIC DINOFLAGELLATE AMPHIDINIUM CRYOPHILUM1

ABSTRACTThe cold‐water, photosynthetic dinoflagellate Amphidinium cryophilum Wedemayer, Wilcox &amp; Graham feeds phagotrophically on other dinoflagellate species. Food is ingested through a feeding tube, termed here the “phagopod,” which extends from the antapex. The peduncle of this organism plays no observable role in the feeding process. The phagopod is essentially a hollow cylinder composed electron‐opaque material that is possibly deposited on a membrane. No Amphidinium cytoplasmic components, including microtubules or other cytoskeletal elements, were observed in the phagopod. Prefeeding cells aggregate, in small clumps near prey organisms with their phagopods extended. Eventually some cells commence feeding, first inserting the phagopod through the prey cell‐covering and then slowly, over a period of 10 min or more, drawing cytoplasm through the phagopod and into a nascent food vacuole. Both light and electron microscopy suggest that one or more prey cell amphiesmal membranes remain intact during the feeding process. Upon completion of feeding, the Amphidinium cell swims off with a prominent food vacuole in the hypocone, leaving at least part of the phagopod attached to the prey cell. Phagotrophy in A. cryophilum seems to vary with light intensity. At low light intensities, cells feed phagotrophically and are nearly colorless, whereas at high light levels they feed much less frequently, if at all, and are brightly pigmented.

EFFECT OF TEMPERATURE DURING MAY TO AUGUST ON TERMINATION OF PROLONGED DIAPAUSE IN THE DOUGLAS-FIR CONE MOTH (LEPIDOPTERA: TORTRICIDAE)

The Douglas-fir cone moth, Barbara coljaxiana (Kearfott) (Lepidoptera: Tortricidae), has the capacity for prolonged diapause, i.e. diapause for two or more winters (Hedlin 1960). This diapause allows for temporal spacing of populations and reduction of intraspecific competition. Specifically, when cone crops are small, excessive moth densities can occur and cause conelet mortality prior to completion of feeding by cone moth larvae, which results in moth mortality. If all moths emerged each year, moth-caused destruction of the conelet population, particularly in years of light production, would have drastic effects on the moth population.

Flounders follow the tides to feed: Evidence from ultrasonic tracking in an estuary

Ultrasonically tagged flounders were tracked in the estuary of the River Bann, Northern Ireland, for periods of between 2 and 12 h (11 fish for a total of 92 h and 2·5 km), during their summer residence. Positions were determined by triangulation with two receivers. All fish remained within 400 m of the release point; on average flounders moved about 270 m during one tidal cycle, equivalent to 830 body lengths, or just over 1 body length per minute. Movements were most likely at dusk, but other parameters were not contingent upon time of day, although no data were gathered at dawn. Frequency, direction, distance, speed and duration of movement and turn rate were all significantly contingent upon state of the tide. The movement data are interpreted in terms of feeding behaviour, supported by results from other parts of the study. At high tide flounders made active but meandering searches for food on the inundated mudflats. Similar but faster searches heading downstream on falling tides reflected (a) completion of feeding while littoral invertebrates were still available and (b) avoidance of stranding. Flounders made infrequent but long and linear passages downstream at low tide, when they tended to bury themselves at the edge of the main channel where there was little food. Subsequently, the fish followed the rising tide upstream so that the cycle of movements kept most fish in the same area of the estuary in the short term. It is suggested that tolerance of changing salinities enables flounders, more than other flatfish species, to exploit dense populations of estuarine intertidal invertebrates as food.

IMPACT OF DAMAGE BY THE DRIEDFRUIT MOTH, VITULA EDMANDSAE SERRATILINEELLA (LEPIDOPTERA: PYRALIDAE), A PEST OF THE ALFALFA LEAFCUTTER BEE, MEGACHILE ROTUNDATA (HYMENOPTERA: MEGACHILIDAE)

AbstractLarvae of the driedfruit moth, Vitula edmandsae serratilineella Ragonot, enter uncapped tunnels in hives of the alfalfa leafcutter bee, Megachile rotundata F., and eat the pollen and nectar provisions of incomplete cells. Significantly more cocoons are destroyed in hives made of pine nesting material than in those made of polystyrene nesting material. However, significantly more tunnel walls are chewed into and through in the polystyrene than in the wood material. A significant positive relationship exists between the number of moth larvae per hive and the number of bee cells produced in that hive. After hives are removed from the field and placed in storage for the winter, most mature larvae leave the tunnels upon completion of feeding and aggregate in spaces between hives.

Feeding Time and Oviposition of Dermacentor variabilis (Acarina: Ixodidae) as Affected by Delayed Mating1

Ixodid ticks commonly mate during attachment and feeding. In many species, females which have commenced feeding will not engorge to repletion until mating occurs. Gregson (1947) demonstrated that Dermacentor andersoni Stiles required a minimum feeding period before either sex would mate. However, the hypothesis that deleterious effects on the engorging females might result from delayed mating apparently has not been tested heretofore. In the natural environment, many female ticks probably are unable to mate for several days after attachment, since males may not always be present in equal numbers on the same host at the same time. If such delays in mating adversely affected the completion of feeding and oviposition, the ability of this species to multiply within its natural environment would be considerably reduced.