Discovery of an undescribed protostrongylid nematode from the endangered pampas deer (Ozotoceros bezoarticus celer) in Argentina

Dorsal-spined protostrongylid nematode larvae (Metastrongyloidea: Protostrongylidae) were recovered from the feces of the endangered pampas deer (Ozotocerus bezoarticus celer) in Campos del Tuyú Wildlife Reserve, Bahia Samborombón, Argentina. Partial DNA sequences from the large subunit ribosomal RNA (LSU rRNA) gene and from the second internal transcribed spacer region (ITS2) were amplified, cloned, sequenced, and compared to those of other nematodes. Nucleotide alignment and phylogenetic analysis of the sequences indicate that this protostrongylid nematode is most closely related to Parelaphostrongylus spp. as inferred from the LSU rRNA sequence analysis. Analysis of the ITS2 spacer indicated that the pampas deer protostrongylid is nested in a clade containing Parelaphostrongylus and Elaphostrongylus spp. These sequences differed considerably from those of other protostrongylid nematodes, and were most similar to those of Parelaphostrongylus spp. and Elaphostrongylus spp. in spite of clear variability from both genera. These results suggest that the protostrongylid from pampas deer is an undescribed nematode that likely belongs in the subfamily Elaphostrongylinae.     

Muskox lungworm (Umingmakstrongylus pallikuukensis) does not establish in experimentally exposed thinhorn sheep (Ovis dalli)

Muskoxen (Ovibos moschlatus moschatus) on the northwestern mainland of Nunavut and Northwest Territories, Canada, are infected with the protostrongylid lungworm, Umingmaksrongylus pallikuuhkensis. The geographic range of this muskox population is expanding to the south and west, and it is anticipated that these animals will eventually become sympatric with Dall's sheep (Ovis dalli dalli) in the Mackenzie and Richardson Mountains. To address the concern of wildlife managers that U. pallikulkensis may infect and adversely affect Dalls sheep, four Dalls/Stone's (Ovis dalli stonei) hybrid lambs and one adult muskox (Ovibos moschatus wardi) were each given 100 third-stage larvae of U. pallikuukensis. All animals were intensively monitored for 9 mo postinfection (PI) using clinical examinations, fecal analyses, hematology, blood chiemistry and medical imaging. No first-stage larvae of U. pallikuinkensis were recovered from the lambs and monitoring revealed nio evidence that the parasite had established in any of these animals. First-stage larvae were found in the feces of the muskox beginning at 94 days PI, and typical parasite cysts were visible in lung radiographs at 188 days PI. This study addresses an important management and wildlife health issue associated with the potential for host-switching of pathogens and indicates that it is improbable that thinhorn sheep are suitable hosts for U. pallikuukensis.     

The potential for false-positive diagnosis of protostrongyliasis by extraction of larvae from feces

The potential of protostrongylid first-stage larvae (L1) to survive passage through the alimentary canal of non-infected mammals was investigated. Parelaphostrongylus tenuis L1 were collected from feces of an experimentally infected white-tailed deer (Odocoileus virginianus). We utilized two red deer (Cervus elaphus) and four laboratory rats (Rattus norvegicus) which were each fed the L1 of P. tenuis. Larvae were recovered, intact and alive, from the fecal samples of all six animals. Larvae of P. tenuis, and probably of other related species, can survive passage through the alimentary canal of uninfected mammals and they can be collected from feces using the Baermann technique and other related larval extraction methods. Rain water was found to be successful in the dispersal of P. tenuis L1 from the feces of infected animals. These findings raise the possibility of ingestion of L1 and their subsequent passage, by uninfected animals. This potential for false-positive diagnosis of infection in live animals necessitates accurate interpretation of a host's infection-status. Such findings reinforce the need for a reliable method of diagnosing infections in live animals.     

Geographic distribution of the muscle-dwelling nematode Parelaphostrongylus odocoilei in North America, using molecular identification of first-stage larvae

Molecular identification of dorsal-spined larvae (DSL) from fecal samples indicates that the protostrongylid parasite Parelaphostrongylus odocoilei occupies a broader geographic range in western North America than has been previously reported. We analyzed 2,124 fecal samples at 29 locations from thinhorn sheep (Ovis dalli dalli and O. d. stonei), bighorn sheep (Ovis canadensis canadensis and O. c. californiana), mountain goats (Oreamnos americanus), woodland caribou (Rangifer tarandus caribou), mule deer (Odocoileus hemionus hemionus), and black-tailed deer (O. h. columbianus). The DSL were recovered from populations of thinhorn sheep south, but not north, of the Arctic Circle, and they were not recovered from any of the bighorn sheep populations that we examined. In total, DSL were recovered from 20 locations in the United States and Canada (Alaska, Yukon Territory, Northwest Territories, British Columbia, Alberta, and California). The DSL were identified as P. odocoilei by comparing sequences of the second internal transcribed spacer (ITS2) region of ribosomal RNA among 9 protostrongylid species validated by adult comparative morphology. The ITS2 sequences were markedly different between Parelaphostrongylus and other protostrongylid genera. Smaller fixed differences served as diagnostic markers for the 3 species of Parelaphostrongylus. The ITS2 sequences (n = 60) of P. odocoilei were strongly conserved across its broad geographic range from California to Alaska. Polymorphism at 5 nucleotide positions was consistent with multiple copies of the ITS2 within individual specimens of P. odocoilei. This work combines extensive fecal surveys, comparative morphology, and molecular diagnostic techniques to describe comprehensively the host associations and geographic distribution of a parasitic helminth.     

Protostrongylid parasites and pneumonia in captive and wild thinhorn sheep (Ovis dalli)

We describe health significance of protostrongylid parasites (Parelaphostrongylus odocoilei and Protostrongylus stilesi) and other respiratory pathogens in more than 50 naturally infected Dall's sheep (Ovis dalli dalli) from the Mackenzie Mountains, Northwest Territories (1998-2002) as well as in three Stone's sheep (O. d. stonei) experimentally infected with P. odocoilei (2000-2002). Histological lesions in the brain and distribution of P. odocoilei in the muscles of experimentally and naturally infected sheep were consistent with a previously hypothesized "central nervous system to muscle" pattern of migration for P. odocoilei. Dimensions of granulomas associated with eggs of P. odocoilei and density of protostrongylid eggs and larvae in the cranial lung correlated with intensity of larvae in feces, and all varied with season of collection. Prevalence of P. stilesi based on the presence of larvae in feces underestimated true prevalence (based on examination of lungs) in wild Dall's sheep collected in summer and fall. Similarly, counts of both types of protostrongylid larvae in feces were unreliable indicators of parasitic infection in wild Dall's sheep with concomitant bacterial pneumonia associated with Arcanobacterium pyogenes, Pasteurella sp., and Mannheimia sp. Diffuse, interstitial pneumonia due to P. odocoilei led to fatal pulmonary hemorrhage and edema after exertion in one experimentally infected Stone's sheep and one naturally infected Dall's sheep. Bacterial and verminous pneumonia associated with pathogens endemic in wild Dall's sheep in the Mackenzie Mountains caused sporadic mortalities. There was no evidence of respiratory viruses or bacterial strains associated with domestic ruminants, from which this population of wild sheep has been historically isolated.     

Identification of dorsal-spined larvae from free-ranging wapiti (Cervus elaphus) in southwestern Manitoba, Canada

Dorsal-spined first-stage larvae recovered from feces of free-ranging wapiti (Cervus elaphus) were passaged through snails (Triodopsis multilineata) and two hand-raised white-tailed deer fawns (Odocoileus virginianus). A total of 74 adult Parelaphostrongylus tenuis were recovered from the fawns; no other protostrongylid nematodes were recovered. The study indicates that wapiti may be infected with natural infections of meningeal worm and pass larvae suitable for transmission to gastropod intermediate hosts. Wapiti from areas endemic with P. tenuis should not be translocated to areas currently free of the parasite.     

Recent observations on the sand fly (Diptera: Psychodidae) fauna of the State of Rondônia, Western Amazônia, Brazil: the importance of Psychdopygus davisi as a vector of zoonotic cutaneous leishmaniasis

Sand flies were collected in the central region of the state of Rond?nia (W 64 degrees 30' to 63 degrees 00' and S 10 degrees 00'to 11 degrees 00') using Shannon and CDC light traps from October 1997 to August 2000. A total of 85,850 specimens representing 78 named species were captured. Of these 14 were new records for Rond?nia. The proportion of males/females was 1/1.131. Trypanosomatids, that are presently being identified, were detected in 11 species. Leishmania (Viannia) naiffi was recorded from Psychodopygus davisi and P. hirsutus. In the present study the dominant species was P. davisi (39.6%) followed by Lutzomyia whitmani (13.1%), P. carrerai (11.6%), and P. hirsutus (10.2%). The importance of P. davisi as a vector of zoonotic cutaneous leishmaniasis is discussed.     

Seasonal and diurnal biting activities and zoonotic filarial infections of two Simulium species (Diptera: Simuliidae) in northern Thailand

Seasonal and daily biting activity patterns, and natural filarial infections of adult black flies attracted to human bait were investigated at Ban Pang Faen, a rural area in Chiang Mai Province in northern Thailand. Collections were carried out twice a month from 0600 to 18-00 hours from January 2005 to February 2006. Among ten Simulium species collected, S. nodosum and S. asakoae were predominant occupying 57.3% and 37.2% of the total 16,553 females, respectively. These two predominant species showed different patterns in seasonal abundance: majority of S. nodosum (86.7%) were collected in hot season (from mid February to mid May), while most of S. asakoae (74.5%) were collected in rainy season (from mid May to mid October). For the daily biting activity, S. nodosum had two patterns: the main one was unimodal with a peak from 17-00 to 18-00, and the other was bimodal and had the major peak from 1600 to 18-00 and the minor one from 07-00 to 09-00. The pattern of S. asakoae was mostly unimodal with a peak from 06-00 to 10-00. The filarial larvae found in S. nodosum and S. asakoae were morphologically different from each other. The short and thick infective larvae found in S. asakoae differed from all known filarial larvae; it is suggested that they might be a bird parasite, Splendidofilariinae or Lemdaninae. The infection of the mammophilic S. nodosum with large Onchocerca type infective larvae was confirmed in this area. Natural filarial infections were found in each month (except December) in either S. nodosum or S. asakoae or in both. Monthly infection rates with all stages of larvae were 0.6-5.0% for S. nodosum, and 1.0-4.0% for S. asakoae. It is suggested that people in this village are exposed to the risk of infection with zoonotic filariae throughout the year.     

Variations in the uptake of 3H-norepinephrine during the rat estrous cycle

The rates of ³H-norepinephrine (³H-NE) uptake into isolated nuclei-free homogenates from diencephalon were examined in freely cycling female rats of all phases of the estrous cycle. Four time points were investigated in each phase: 12:00, 14:00, 16:00 and 18:00 h. The proestrus and estrus animals displayed no change in uptake rates across the four time points. However, the metestrus and diestrus groups were found to undergo hour to hour variations in uptake rates. In the diestrus group, a significant rise in uptake of 22% was observed from 12:00 to 16:00 h. This increase was followed by a decrease of 21% by 18:00 h as compared to 16:00 h levels. Similarly, a slight increase in uptake was observed in the metustrus animals from 12:00 to 16:00 h. At 18:00 h a 40% decrease from the 16:00 h value was observed. An average of the mean levels of uptake of all phases was calculated for each time point. At 16:00 h an increase in the mean uptake of about 20% was observed when compared to either the 12:00 or the 18:00 h values. Since transmitter reuotake is the major means of terminating receptor activation or inhibition, it is suggested that the above variations in NE uptake may modulate synaptic activity and play a role in the regulation of behavioral and physiological aspects of the estrous cycle.     

The role of protein synthesis in regulation of oestradiol-17 beta in the pro-oestrous hamster

Injection (s.c.) of 2 mg cycloheximide at 14:00 h on the day of pro-oestrus prevented the normal rise in serum progesterone and significantly lowered progesterone levels at 15:00 h. Values then rose but only to approximately half of the control values between 16:00 h and 19:00 h. Oestradiol levels also decreased drastically by 15:00 h but were significantly higher in cycloheximide-treated animals until 19:00 h. FSH and LH concentrations were not affected when cycloheximide was given at 14:00 h but treatment at 10:00 h resulted in generally lower values. Animals treated with cycloheximide at 14:00 h failed to ovulate (N = 9), but simultaneous injection of 50 micrograms progesterone restored ovulation in 50% of the treated animals. In contrast, hamsters injected with cycloheximide at 10:00 h ovulated the next morning, suggesting that protein synthesis essential for ovulation is limited to the first 4-5 h after the release of LH.     

Differentiation of dorsal-spined elaphostrongyline larvae by polymerase chain reaction amplification of ITS-2 of rDNA

Molecular genetics was used to devise the first reliable diagnostic tool for differentiating morphologically indistinguishable dorsal-spined, first-stage larvae (L1's) and other stages of the nematode protostrongylid subfamily Elaphostrongylinae. A polymerase chain reaction (PCR) assay employing specifically designed primers was developed to selectively amplify DNA of the ITS-2 region of the ribosomal gene. Amplification of the entire ITS-2 region differentiated between larvae of the genera Elaphostrongylus and Parelaphostrongylus, based on the lengths of fragments produced. Three sets of primers were designed and used successfully to distinguish larvae at the species level. Although it was demonstrated that one primer set in a single PCR assay was capable of distinguishing each of the three Parelaphostrongylus spp., a second primer set would be required for confirmation in routine diagnostic use. Two of the three primer sets were capable of amplifying DNA from all six elaphostrongyline species and of identifying Elaphostrongylus alces and Parelaphostrongylus odocoilei. Although two separate fragments were produced from each Elaphostrongylus cervi and Elaphostrongylus rangiferi, it was not possible to distinguish these two parasites from each other based on the fragment size. The use of various nematodes, hosts, and fecal controls demonstrated the reliability of the primers for all developmental stages including L1's, third-stage larvae, and adult worms. These primers also have potential for identifying other lungworms as was shown by the amplification of Umingmakstrongylus pallikuukensis, the muskox protostrongylid, and Dictyocaulus sp. from white-tailed deer. Although this assay may benefit from further refinement, its present design provides researchers, wildlife managers, clinicians, and animal health regulators with a practical tool for the control, management, and study of meningeal and tissue worms and their close relatives.     

Seasonal rhythms of body temperature in the free-ranging raccoon dog (Nyctereutes procyonoides) with special emphasis on winter sleep

The raccoon dog (Nyctereutes procyonoides) is the only canid with passive overwintering in areas with cold winters, but the depth and rhythmicity of wintertime hypothermia in the wild raccoon dog are unknown. To study the seasonal rhythms of body temperature (T(b)), seven free-ranging animals were captured and implanted with intra-abdominal T(b) loggers and radio-tracked during years 2004-2006. The average size of the home ranges was 306+/-26 ha, and the average 24 h T(b) was 38.0+/-<0.01 degrees C during the snow-free period (May-November). The highest and lowest T(b) were usually recorded around midnight (21:00-02:00 h) and between 05:00-11:00 h, respectively, and the range of the 24 h oscillations was 1.2+/-0.01 degrees C. The animals lost approximately 43+/-6% of body mass in winter (December-April), when the average size of the home ranges was 372+/-108 ha. During the 2-9-wk periods of passivity in January-March, the average 24 h T(b) decreased by 1.4-2.1 degrees C compared to the snow-free period. The raccoon dogs were hypothermic for 5 h in the morning (06:00-11:00 h), whereas the highest T(b) values were recorded between 16:00-23:00 h. The range of the 24 h oscillations increased by approximately 0.6 degrees C, and the rhythmicity was more pronounced than in the snow-free period. The ambient temperature and depth of snow cover were important determinants of the seasonal T(b) rhythms. The overwintering strategy of the raccoon dog resembled the patterns of winter sleep in bears and badgers, but the wintertime passivity of the species was more intermittent and the decrease in the T(b) less pronounced.     

Parelaphostrongylus odocoilei in Columbian black-tailed deer from Oregon

Documenting the occurrence of Parelaphostrongylus odocoilei has historically relied on the morphological examination of adult worms collected from the skeletal muscle of definitive hosts, including deer. Recent advances in the knowledge of protostrongylid genetic sequences now permit larvae to be identified. Dorsal-spined larvae (DSLs) collected in 2003-2004 from the lung and feces of six Columbian black-tailed deer (Odocoileus hemionus columbianus) from Oregon were characterized genetically. The sequences from unknown DSLs were compared to those from morphologically validated adults and larvae of P. odocoilei at both the second internal transcribed spacer (ITS-2) of ribosomal DNA and the mitochondrial cytochrome oxidase II gene. We provide the first unequivocal identification of P. odocoilei in Columbian black-tailed deer from Oregon. The broader geographic distribution, prevalence, and pathology of P. odocoilei are not known in populations of Oregon deer.     

Comparative Study of the Activity/Rest Rhythms in Young and Old Ringdove (Streptopelia Risoria): Correlation with Serum Levels of Melatonin and Serotonin

Aging is characterized by changes in the circadian rhythms of melatonin, serotonin, and sleep/wakefulness, alterations that affect sleep quality. The authors studied the circadian rhythms of serotonin and melatonin in young and old ringdoves (Streptopelia risoria) (2–3 and 10–12 yrs old, respectively), animals that are characterized by being monophasic and active by day, like humans. The aim was to correlate the indole rhythms with the animals' activity/rest periods. The animals were kept under a 12∶12 h light/dark cycle, fed ad libitum, and housed in separate cages equipped for activity recording. Activity pulses were recorded with one actometer per animal (two perpendicular infrared transmitters) and were logged every 15 min by a computer program (DAS 16) throughout the experiment. Melatonin was measured by radioimmunoassay and serotonin by ELISA at intervals of 3 h (from 09∶00 to 18∶00 h) and 1 h (from 21∶00 to 06∶00 h), respectively. The results showed a reduction in nocturnal vs. diurnal activity of 89% and 61% in the young and old animals, respectively, with 100% considered to be the diurnal activity of each group. The amplitude of a cosine function fit to the melatonin concentrations of the old animals was half that of the young birds. The acrophase and nadir were at 02∶00 and 14∶00 h in the young and 01∶00 and 13∶00 h in the old animals, respectively. The amplitude of the corresponding cosine function fit to the serotonin concentrations in the old birds was one‐third that of the young animals. The acrophase and nadir were at 15∶00 and 03∶00 h in the young and 16∶00 and 04∶00 h in the old animals, respectively. For both melatonin and serotonin, the concentrations in the young animals were significantly higher than in the old at most of the measurement times. There was a clear negative correlation between the circadian rhythms of activity and the serum melatonin levels in both young and old animals. The equivalent correlation for serotonin was positive, and stronger in the case of the young animals. The results suggest a possible relationship between the observed decline in the amplitude of the old animals' melatonin and serotonin rhythms and the lower percentage reduction in their nocturnal relative to diurnal activity pulses compared to the young animals. In conclusion, the circadian rhythms of melatonin and serotonin undergo alterations with age that could be involved in the changes in age‐associated sleep.     

秦岭羚牛春夏季昼夜活动节律与时间分配

1996年4~8月,在陕西省佛坪自然保护区内采用无线电遥测技术对4只秦岭羚牛（Budorcas taxicolor bedfordi）的活动规律进行了研究。春夏季羚牛的活动规律以白昼活动为主。羚牛每昼夜有69.95+11.06%的时间处于活动状态（n=40）,其中76.77%的活动时间是在日出后到日落前的白昼。白昼有3个活动高峰期,分别出现在06:00~08:00、10：00~12：00、18：00~20：00 3个时间段。在夜间羚牛只有1个活动高峰期,通常出现在24：00至次日凌晨01：00的时间段。野外观察证实,羚牛白昼的3个活动高峰期与羚牛群体活跃采食的时间吻合。羚牛的昼夜活动节律的形成与变化,可能会受到诸如光照、温度、雨等气候条件的影响。每天的黎明阶段（06：00~07：00）及黄昏阶段（18：30~19：30）是羚牛活动最频繁的时候,平均活动率在90%以上。大雨期间羚牛常常站立或卧地休息。此外,羚牛昼夜活动节律和时间分配方面的差异在年龄上也有所体现。     

Evaluation of a timed and repeated perianal tape test for the detection of pinworms (Trypanoxyuris microon) in owl monkeys (Aotus nancymae)

The purpose of this project was to determine if the detection of pinworm infections in owl monkeys (Aotus nancymae) could be improved by performing perianal tape testing at specific times of the day and/or by performing repeated sampling. Eight Aotus known to be infected with pinworms were sampled at four selected time points (06:00, 12:00, 18:00 and 24:00 hours) over the course of a 3-week period. Samples were examined microscopically and oxyurid eggs were quantified. Results revealed no significant differences in time points, but did indicate that repeated sampling significantly improved pinworm egg detection. Results also determined that Aotus housed with an infected cage mate are at an approximately 14-times greater risk of being infected than animals housed without an infected cage mate. Lastly, results indicated no significant difference between peripheral eosinophil and basophil numbers from infected and clean animals.     

Effects of summer frost exposures on the cold tolerance strategy of a sub-Antarctic beetle

The sub-Antarctic beetle Hydromedion sparsutum (Coleoptera, Perimylopidae) is common locally on the island of South Georgia where sub-zero temperatures can be experienced in any month of the year. Larvae were known to be weakly freeze tolerant in summer with a mean supercooling point (SCP) around -4 degrees C and a lower lethal temperature of -10 degrees C (15min exposure). This study investigated the effects of successive freezing exposures on the SCP and subsequent survival of summer acclimatised larvae. The mean SCP of field fresh larvae was -4.2+/-0.2 degrees C with a range from -1.0 to -6.1 degrees C. When larvae were cooled to -6.5 degrees C on 10 occasions at intervals of 30min and one and four days, survival was 44, 70 and 68%, respectively. The 'end of experiment' SCP of larvae surviving 10 exposures at -6.5 degrees C showed distinct changes and patterns from the original field population depending on the interval between exposure. In the 30min interval group, most larvae froze between -6 and -8 degrees C, a depression of up to 6 degrees C from the original sample; all larvae were dead when cooling was continued below the SCP to -12 degrees C. In the one and four day interval groups, most larvae froze above -6 degrees C, showing no change as a result of the 10 exposures at -6.5 degrees C. As with the 30min interval group, some larvae froze below -6 degrees C, but with a wider range, and again, all were dead when cooled to -12 degrees C. However, in the one and four day interval groups, some larvae remained unfrozen when cooled to -12 degrees C, a depression of their individual SCP of at least 6 degrees C, and were alive 24h after cooling. In a further experiment, larvae were cooled to their individual SCP temperature at daily intervals on 10 occasions to ensure that every larva froze every day. Most larvae which showed a depression of their SCP of 2-4 degrees C from their day one value became moribund or died after six or seven freezing events. Survival was highest in larvae with SCPs of -2 to -3 degrees C on day one and which froze at this level on all 10 occasions. The results indicate that in larvae in which the SCP is lowered following sub-zero exposure, the depression of the SCP is greatest in individuals that do not actually freeze. Further, the data suggest that after successive frost exposures in early winter the larval population may become segregated into two sub-populations with different overwintering strategies. One group consists of larvae that freeze consistently in the temperature range from -1 to -3 degrees C and can survive multiple freeze-thaw cycles. A second group with lower initial SCPs (around -6 degrees C), or which fall to this level or lower (down to -12 degrees C) after freezing on one or more occasions, are less likely to freeze through extended supercooling, but more likely to die if freezing occurs.     

Comparative study of the activity/rest rhythms in young and old ringdove (Streptopelia risoria): correlation with serum levels of melatonin and serotonin

Aging is characterized by changes in the circadian rhythms of melatonin, serotonin, and sleep/wakefulness, alterations that affect sleep quality. The authors studied the circadian rhythms of serotonin and melatonin in young and old ringdoves (Streptopelia risoria) (2-3 and 10-12 yrs old, respectively), animals that are characterized by being monophasic and active by day, like humans. The aim was to correlate the indole rhythms with the animals' activity/rest periods. The animals were kept under a 12:12 h light/dark cycle, fed ad libitum, and housed in separate cages equipped for activity recording. Activity pulses were recorded with one actometer per animal (two perpendicular infrared transmitters) and were logged every 15 min by a computer program (DAS 16) throughout the experiment. Melatonin was measured by radioimmunoassay and serotonin by ELISA at intervals of 3 h (from 09:00 to 18:00 h) and 1 h (from 21:00 to 06:00 h), respectively. The results showed a reduction in nocturnal vs. diurnal activity of 89% and 61% in the young and old animals, respectively, with 100% considered to be the diurnal activity of each group. The amplitude of a cosine function fit to the melatonin concentrations of the old animals was half that of the young birds. The acrophase and nadir were at 02:00 and 14:00 h in the young and 01:00 and 13:00 h in the old animals, respectively. The amplitude of the corresponding cosine function fit to the serotonin concentrations in the old birds was one-third that of the young animals. The acrophase and nadir were at 15:00 and 03:00 h in the young and 16:00 and 04:00 h in the old animals, respectively. For both melatonin and serotonin, the concentrations in the young animals were significantly higher than in the old at most of the measurement times. There was a clear negative correlation between the circadian rhythms of activity and the serum melatonin levels in both young and old animals. The equivalent correlation for serotonin was positive, and stronger in the case of the young animals. The results suggest a possible relationship between the observed decline in the amplitude of the old animals' melatonin and serotonin rhythms and the lower percentage reduction in their nocturnal relative to diurnal activity pulses compared to the young animals. In conclusion, the circadian rhythms of melatonin and serotonin undergo alterations with age that could be involved in the changes in age-associated sleep.     

Resistance to ivermectin by Haemonchus contortus in goats and calves.

Efficacy of ivermectin on susceptible or resistant populations of the parasitic nematode Haemonchus contortus was determined in cattle and goats held in a barn. Goats were each infected with 3000 infective, ivermectin-susceptible or -resistant H. contortus larvae on day 0 and reinfected with 2000 infective larvae on day 24. Goats were treated orally with 600 micrograms kg-1 ivermectin on day 31. No significant differences were detected in blood packed cell volume (PCV) or total protein (TP), prepatent period, or epg among the four groups of goats that were each infected with one of four parasite strains (one susceptible, three resistant). There were no differences among the four parasite strains in the numbers of infective larvae that developed to the third larval stage from fecal cultures or in the viability of cultured infective larvae when held in the laboratory at 27 +/- 1 degrees C for 14 weeks. After treatment with ivermectin, there were significant differences among the parasite strains in PCV, TP, and epg. Total worm counts were reduced by 94 to 97% with three times the recommended dose. Immature and adult Skrjabinema ovis were also present in two treated goats. In a second test, one goat infected once with 10,000 infective larvae of a resistant strain of H. contortus and then treated with nine doses of ivermectin, increasing from 500 to 2000 micrograms kg-1 over a period of 133 days, had 35 adult worms at necropsy. In a third test, three calves were readily infected with an ivermectin-resistant strain of H. contortus from goats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Developmental temperature effects on five geographic isolates of the entomopathogenic nematode Steinernema feltiae (Nematoda: Steinernematidae).

The development of five geographic isolates of Steinernema feltiae at 5, 8, 10, 15, 20, 25, and 28 degrees C in wax moth, Galleria mellonella, larvae was examined. The isolates were from Mediterranean (Sinop from Turkey, SN from France, and Monterey from California), subtropical (Rafaela from Argentina), and tropical (MG-14 from Hawaii) regions. All isolates caused 100% mortality of wax moth larvae and developed and produced progeny between 8 and 25 degrees C. At 28 degrees C, mortality was 100%, but no progeny was observed. The highest infective juvenile production was observed at 15 degrees C for all isolates. In general, the tropical isolate, MG-14, had the lowest production of infective juveniles. The time of emergence of the infective juveniles from the host cadaver showed some differences among isolates, with the Sinop isolate having the earliest emergence time from cadavers at 15 degrees C (10 days) and 20 degrees C (8 days). At 25 degrees C, the infective juveniles of the Sinop, SN, and Rafaela isolates emerged from the cadavers from 5 to 7 days. Time of host death by all isolates showed no differences at 8, 10, 15, 20, and 28 degrees C. At 25 degrees C for all isolates (except the MG-14), shorter times to host death were observed. Host death occurred at 12 days at 8 degrees C, 9 to 11 days at 10 degrees C, 4 to 5 days at 15 degrees C, 3 days at 20 degrees C, and 2 days at 25 and 28 degrees C. For penetration efficiency, the Sinop, SN, and Rafaela isolates penetrated their hosts at 5, 8, and 10 degrees C. Penetration of the infective juveniles was consistently high for all isolates at 15, 20, 25, and 28 degrees C, but it was significantly lower for the MG-14 isolate at 15, 25, and 28 degrees C. No progeny production occurred at 28 degrees C, but nematode penetration did occur with the MG-14 isolate having significantly lower penetration than the other isolates. When nematodes were produced at 8, 15, and 23 degrees C in wax moth larvae, all isolates had infective juveniles with longer body lengths at 8 degrees C followed by 15 and 23 degrees C. To further verify body length at the different temperatures, beet armyworm, Spodoptera exigua, larvae and dog-food agar medium were used, respectively, for in vivo and in vitro culture of the Sinop isolate. Infective juvenile body length showed the same trends, with the longest being at 8 degrees C and decreasing in length from 15 to 23 degrees C. The data suggest that quality of food for the nematode and temperature (that is, developmental time) influence the body length of the infective juvenile.