Behavior of red king crab larvae: phototaxis, geotaxis and rheotaxis

Zoeae of Paralithodes camtschatica were positively phototactic to white light intensities above 1 x 10(13) q cm-2 s-1. Negative phototaxis occurred at low (1 x 10(12) q cm-2 s-1), but not high intensities (2.2 x 10(16) q cm-2 s-1). Phototactic response was directly related to light intensity. Zoeae also responded to red, green and blue light. Zoeae were negatively geotactic, but geotaxis was dominated by phototaxis. Horizontal swimming speed of stage 1 zoeae < 4 d old was 2.4 +/- 0.1 (SE) cm s-1 and decreased to 1.7 +/- 0.1 cm s-1 in older zoeae (P < 0.01). Horizontal swimming speed of stage 2 zoeae was not significantly different from > or = 4 d old stage 1 zoeae. Vertical swimming speed, 1.6 +/- 0.1 cm s-1, and sinking rate, 0.7 +/- 0.1 cm s-1, did not change with ontogeny. King crab zoeae were positively rheotactic and maintained position in horizontal currents less than 1.4 cm s-1. Starvation reduced swimming and sinking rates and phototactic response.     

Prevalence of ixodid ticks on cattle in Mazandaran province, Iran

A survey was carried out to investigate the prevalence of hard tick species (Acari: Ixodidae) on cattle in Mazandaran province, Iran. A total of 953 ticks were collected from 86 infested cattle during activating seasons of ticks during 2004-2005. Nine species were identified: Boophilus annulatus (51.3%), Rhipicephalus bursa (16.8%), Haemaphysalis punctata (6.3%), Ixodes ricinus (6.8%), Hyalomma marginatum (12.5%), Hyalomma anatolicum excavatum (5.2%), Hyalomma asiaticum (0.6%), Hyalomma detritum (0.2 %), and Dermacentor spp. (0.1%). The results show that Boophilus annulatus, Rhipicephalus bursa, and Hyalomma species are dominant tick species in the surveyed area.     

Experimental transmission of Crimean-Congo hemorrhagic fever virus: role of 3 vector species in the maintenance and transmission cycles in Senegal

In this article, we published the role of three species of ticks Amblyomma variegatum (Fabricius, 1974), Hyalomma marginatum rufipes (Koch, 1844) and Hyalomma truncatum (Koch, 1844) in the maintenance and transmission of the CCHF virus. The imagos of these species were infected by intracoelomic route. Vertical transmission (transtasial and transovarial) and horizontal transmission for different stases were studied by isolation on newborn mice, polymerase chain reaction, indirect immunofluorescence and ELISA. Our results proved that 15 days after inoculation, infection rates of 100% were noted with Hyalomma marginatum rufipes and Hyalomma truncatum. This rate is about 60% for Amblyomma variegatum. The imagos of the three species infected have transmitted the virus to their host during blood feeding (100%). A high transovarial transmission for Hyalomma marginatum rufipes and Hyalomma truncatum were observed (respectively 53 and 50%). This rate is about 12% for Amblyomma variegatum. The tick infection does not persist up to the first generation for the three species studied. Ticks are temporary reservoirs vectors but not permanent reservoirs of CCHF virus.     

Visual potentialities of the tick Hyalomma asiaticum asiaticum (Ixodidae)

Ethological experiments with the desert tick Hyalomma asiaticum asiaticum are conducted. It is shown that tick inhabiting open landscapes discovers his host using his eyes. Since the eyes of this species have a poor resolving possibility, black objects with white strips drawn on it are less attractive for the tick. When the tick scans an area looking for host, the principal optical axis of his eyes is directed not higher than 20 degrees. In allows the tick to discover objects having angular sizes of 5 degrees and greater.     

Monthly dynamics of ticks (Acari: Ixodida) infesting N'Dama cattle in the Republic of Guinea

The occurrence of ixodid ticks on N'Dama cattle was studied in the Republic of Guinea between June 1994 and May 1995. Monthly tick collections were performed on 80 animals from 14 villages located in Dabola, Kouroussa and Dinguiraye prefectures. A total of 19,804 ticks was collected and classified using standard taxonomic keys. The following tick species were identified: Amblyomma variegatum, Hyalomma marginatum rufipes, Hyalomma trunctum, Hyalomma nitidum, Rhipicephalus lunulatus, Rhipicephalus muhsamae, Rhipicephalus senegalensis, Rhipicephalus sulcatus, Rhipicephalus turanicus, Boophilus annulatus, Boophilus geigyi. Boophilus spp. were the most numerous adult ticks (57.1%), Am. variegatum adults constituted 27.4%, while 12.4% were Rhipicephalus spp. and 2.5% Hyalomma spp. Rhipicephalus turanicus and Hyalomma nitidum were recorded for the first time in the country. Am. variegatum and Boophilus spp. were present throughout the year, whereas Am. variegatum adults showed a peak during the rainy season between April and September. Immature stages collected belonged exclusively to the genera Amblyomma and Boophilus. Am. variegatum larvae and nymphs showed a peak during the dry season (October-March); no significant variation between seasons was observed for Boophilus immatures. A significantly higher infestation of cattle by Rhipicephalus spp. was found in Dabola and Kouroussa prefectures, located in the southern part of the study area, with similar climatic, vegetation and rainfall characteristics. Possible options for the control of ticks in the study area are briefly discussed.     

An attempt to stimulate cell division in Saccharomyces cerevisiae with weak ultraviolet light

Liquid cultures of the yeast Saccharomyces cerevisiae were irradiated with weak light having irradiances ranging from ca. 1 X 10(2) to 5 X 10(9) photons cm-2 s-1 and at wavelengths ranging from 200 to 700 nm. When particular care was taken to control the temperature of the cultures and the flow rate of oxygen, no evidence was obtained for stimulation of either yeast growth or division by the incident light. These results do not support the claims of early workers that very low intensity uv light can stimulate cell division in living organisms.     

A comparison of electrophysiologically determined spectral responses in 35 species of Lepidoptera

Spectral responses from the compound eyes of 35 lepidopteran species representing 14 families were investigated electrophysiologically using ERG recordings. The light-stimuli used overed the range of 383–700 nm wavelengths. All species show three or four maxima in their spectral sensitivity curves. Two of these peaks were usually associated with ultraviolet and blue light (383 and 460 nm, respectively). The other maxima occurred in the 500–620 nm region. In Nymphalidae the highest peak was found in response to 560–580 nm stimuli. Of all wavelengths tested, these are the longest wavelengths to produce principal peak sensitivities.Pieridae and Lycaenidae have maxima in the UV region which represent significantly higher sensitivities than the secondary peaks to stimuli of longer wavelengths.Satyridae, Danaidae, Hesperiidae and diurnal moths except Epicopeia (Epicopeidae) generally have similar sensitivity curves with principal peaks between 500 and 520 nm.In Papilionid species except Graphium (max = 560 nm) high maxima occur in the UV and blue (460 nm) region.Noctural Sphingid moths possess the highest peak sensitivity at 540 nm. All other noctural moths tested have three or four maxima.     

Photoinhibition of chlamydosporulation of Candida albicans]

Candida albicans produced chlamydospores after 24 h in the dark at 27 degrees C, but the process was inhibited under adequate irradiation of light. The in vivo absorption spectra showed a main peak at 414 nm, and less important peaks at 430, 446, 477, 519, 549 and 560 nm. No bands were detected beyond 600 nm. A total inhibition of chlamydosporulation occurred at 414 nm (monochromatic light) for an initial energy of 2,000 ergs cm-2 s-1. A 4,000 ergs cm-2 s-1 irradiation energy was necessary to observe a marked inhibition at 460, 500 and 530 nm (les chlamydospores and/or immaturity); this energy must be raised to 300,000 ergs cm-2 s-1 to observe a similar effect at 575 and 630 nm. Biological activity spectra were in full concordance with absorption spectra at 414 nm; no interpretation of absorption band at 460 nm is given, but total or partial inhibition could be explained by modulation of protoporphyrin activity.     

Immunohistochemical evidence for multiple photosystems in box jellyfish

Cubomedusae (box jellyfish) possess a remarkable visual system with 24 eyes distributed in four sensory structures termed rhopalia. Each rhopalium is equipped with six eyes: two pairs of pigment cup eyes and two unpaired lens eyes. Each eye type probably captures specific features of the visual environment. To investigate whether multiple types of photoreceptor cells are present in the rhopalium, and whether the different eye types possess different types of photoreceptors, we have used immunohistochemistry with a range of vertebrate opsin antibodies to label the photoreceptors, and electroretinograms (ERG) to determine their spectral sensitivity. All photoreceptor cells of the two lens eyes of the box jellyfish Tripedalia cystophora and Carybdea marsupialis displayed immunoreactivity for an antibody directed against the zebrafish ultraviolet (UV) opsin, but not against any of eight other rhodopsin or cone opsin antibodies tested. In neither of the two species were the pigment cup eyes immunoreactive for any of the opsin antibodies. ERG analysis of the Carybdea lower lens eyes demonstrated a single spectral sensitivity maximum at 485 nm suggesting the presence of a single opsin type. Our data demonstrate that the lens eyes of box jellyfish utilize a single opsin and are thus color-blind, and that there is probably a different photopigment in the pigment cup eyes. The results support our hypothesis that the lens eyes and the pigment cup eyes of box jellyfish are involved in different and specific visual tasks.     

光谱和光强度对西花蓟马雌虫趋光行为的影响

利用行为学方法研究了光谱、光强对西花蓟马Frankliniella occidentalis (Pergande)雌成虫的趋、避光行为的影响。结果显示：（1）在340~605nm波谱内14个波长其光谱趋光行为反应为多峰型,峰间主次较明显。趋光行为反应中,蓝绿区498~524nm有一较宽峰,趋光率20.31%;其它各峰依大小次序分别位于紫光380nm、蓝光440nm;（２）避光行为反应中,蓝光440nm处略高,避光率17.19%;紫外340nm处亦有一峰,避光率15.63%;（３）随光强增强其趋光反应率增大,白光、380nm和524nm刺激时其光强趋光行为反应呈一倒“L”型式样,498nm为峰型,440nm时为一较缓的平直线型;光强最弱时仍均有一定趋光率 ,最强时均未出现高端平台;（４）随光强增强其避光反应率增大,440nm为较平缓直线;340nm刺激时为较缓波动线。结果表明：光谱对其趋光行为有很大影响,光强度的影响较大且影响大小与波长因素有关。     

Seasonal prevalence of ticks and tick-transmitted haemoparasites in traditionally managed N'Dama cattle with reference to strategic tick control in the Gambia

Abstract A survey of tick spatial and seasonal distribution in traditional managed N' Dama cattle over 1 year old was carried out in The Gambia over 16 months. Presence of Anaplasma marginale and Babesia spp. in the blood smears and their antibodies in the serum of same animals were also examined. Tick species, in decreasing order of abundance, were: Boophilus geigy, Rhipicephalus senegalensis, B.decoloratus, Hyalomma truncatum, H. marginatum rufipes and Amblyomma variegatum. All tick species peaked during the rainy season. Additional B.geigy peaks occurred towards the end of the dry season. The most infested animal body areas were anogenital, udder and abdomen. A.variegatum, Hyalomma spp. and, to a lesser extent, Boophilus spp. showed strong preferences for these anatomical regions. Overall prevalence of A.marginale, B.bigemina and B.bovis haemoparasites were 3.2%, 0.9% and 0.1 %, respectively. Peaks of A.marginale and B.bigemina occurred at the end of the rainy season-beginning of the dry season; an additional A.marginale peak was observed at mid-end dry season. Overall antibody seroprevalence were 29.6% for A.marginale , 44.7% for B.bigemina and 5.2% for B.bovis; monthly fluctuations in percentage of seroreactors were limited. Endemic stability for A.marginale and B.bigemina is postulated. Implications of the outcomes are discussed in relation to tick-control strategy in The Gambia.     

Spectral Sensitivities of Wolf Spider Eyes

ERG's to spectral lights were recorded from all eyes of intact wolf spiders. Secondary eyes have maximum relative sensitivities at 505–510 nm which are unchanged by chromatic adaptations. Principal eyes have ultraviolet sensitivities which are 10 to 100 times greater at 380 nm than at 505 nm. However, two animals' eyes initially had greater blue-green sensitivities, then in 7 to 10 wk dropped 4 to 6 log units in absolute sensitivity in the visible, less in the ultraviolet. Chromatic adaptations of both types of principal eyes hardly changed relative spectral sensitivities. Small decreases in relative sensitivity in the visible with orange adaptations were possibly retinomotor in origin. Second peaks in ERG waveforms were elicited from ultraviolet-adapted principal eyes by wavelengths 400 nm and longer, and from blue-, yellow-, and orange-adapted secondary eyes by wavelengths 580 nm and longer. The second peaks in waveforms were most likely responses of unilluminated eyes to scattered light. It is concluded that both principal and secondary eyes contain cells with a visual pigment absorbing maximally at 505–510 nm. The variable absolute and ultraviolet sensitivities of principal eyes may be due to a second pigment in the same cells or to an ultraviolet-absorbing accessory pigment which excites the 505 nm absorbing visual pigment by radiationless energy transfer.     

铜绿丽金龟对不同光谱的行为反应

【目的】旨在获得铜绿丽金龟 Anomala corpulenta Motschulsky敏感的波谱范围及性别差异。【方法】本研究利用室内行为学的方法,测试了在波长为340~610 nm的14个单色光刺激下铜绿丽金龟的趋、避光行为反应,并计算趋、避光反应率曲线。【结果】观测显示,各单色光均能引起铜绿丽金龟产生一定的趋、避光反应,其雌雄虫的趋光敏感光区位于紫外光（405 nm）、蓝光（460 nm）和绿光区（505和570 nm）,性别对趋光行为有一定的影响,但是仅存在于趋光反应率曲线波峰的大小,而对波峰的位置没有影响。铜绿丽金龟的避光行为反应,在雌雄之间无明显的性别分化,其避光敏感光谱为紫外光（380 nm）、蓝光（440 nm）和绿光区（492和505 nm）。【结论】铜绿丽金龟成虫对不同波长光的趋性存在差异,性别对其光谱行为反应有一定的影响。该研究结果为铜绿丽金龟光视觉的深入研究奠定必要的理论基础,也为利用其趋光性对该金龟甲进行综合治理提供科学依据。     

Kinetic properties of toxic protease inhibitors isolated from tick eggs

1. Egg-toxins from Rhipicephalus evertsi evertsi, Boophilus microplus, Boophilus decoloratus and Hyalomma truncatum were found to be inhibitors of trypsin and in two cases also of chymotrypsin. 2. Fast tight-binding and slow-binding inhibition were observed. 3. Immunological identity of the toxins were assessed with Ouchterlony immunodiffusion and ELISA. 4. The protease content of B. decoloratus and Amblyomma hebraeum tick eggs were determined by a linked enzyme assay. 5. The predictive value of the kinetic constants in inferring a possible physiological role was discussed.     

Comparison of resistance in three breeds of cattle against African ixodid ticks

Tick resistance in three breeds of cattle, two indigenous breeds (Arssi and Boran) and one Boran x Friesian cross-breed, were compared following natural tick infestations at Abernossa ranch in Ethiopia. The local Arssi breed was found to have the highest tick resistance, followed by the Boran breed, whereas the Boran x Friesian was the least resistant. Over a period of 12 months, from October 1991 to September 1992, a total of 32 897 ticks composed of four genera were collected from the animals. The four most abundant tick species were Amblyomma variegatum (61.7%), Boophilus decoloratus (16%); Rhipicephalus evertsi evertsi (16.3%) and Hyalomma marginatum rufipes (3.7%). Furthermore, 63.5% of all ticks were collected from cross-breed cattle, and 26.2% from the Boran, whereas the local Arssi breed carried only 10.3%. The results indicated that cattle resistant to one species of tick were also resistant to other tick species.     

Ultrastructure and phototactic action spectra of two genera of cryptophyte flagellate algae,Cryptomonas and Chroomonas

Summary A comparative action spectroscopical study was made on phototaxis in two genera of cryptomonads (cryptophyte flagellate algae), namely,Cryptomonas (rostratiformis) andChroomonas (nordstedtii andcoeruled). The two genera differ in their characteristic phycobilin pigmentation and, among three species, onlyChroomonas coerulea possesses an eyespot. The two species with no eyespot,Cryptomonas rostratiformis andChroomonas nordstedtii, exhibited positive phototaxis, showing very similar action spectra characterized by a broad band in the region from 450 nm to 650 nm, with an action maximum at about 560 nm; these features are essentially the same as those observed previously forCryptomonas strain CR-1. InCryptomonas rostratiformis, a small peak was also found at 280 nm in the UV-B/C region.Chroomonas coerulea, with eyespot, did not exhibit distinct positive phototaxis in a wide spectral region at any given, even very low, light intensity, but exhibited negative phototaxis of spectral sensitivity maximal at 400–450 nm. These results indicate that the positive phototaxis ofCryptomonas (rostratiformis and CR-1) andChroomonas nordstedtii is mediated by the same, yet unidentified photoreceptor(s).Chroomonas nordstedtii, possessing no phycoerythrin absorbing at 545 nm, also exhibits positive phototaxis at ca. 560 nm, and this result disfavors the so far proposed possibility that the positive phototaxis of the cryptophytes may be mediated by phycobilin pigments. On the other hand, the spectral characteristics of negative phototaxis ofChroomonas coerulea can possibly be ascribed to the presence of an eyespot.     

Tick prevalence and species diversity on Aldabran giant tortoises (Dipsochelys dussumieri) in relation to host range and host size in a restored ecosystem, Kenya

Tick species density and diversity on Aldabran tortoises was investigated in relation to the habitat range and size of each tortoise. Identification of tick infestation patterns forms an important aspect of effective tick control. Ten Aldabran tortoises were de‐ticked and monitored over the course of 2 months. Tick species found were Amblyomma sparsum, Amblyomma nuttalli, Amblyomma hebraeum and Boophilus decoloratus, with the most prevalent species found being A. sparsum. Tick loads varied considerably from 20 to 214 ticks per tortoise, with most ticks collected from the head/neck region. Tortoises ranging outside Haller Park had higher tick loads (70–214) compared with tortoises ranging within Haller Park (20–99). Tick load was not correlated with tortoise size. Results indicate that tick loads are related to the habitat range of the tortoises and may indirectly also be related to food preference and host food availability. Implications of the findings and appropriate tick control measures are discussed.     

铜绿丽金龟对圆偏振光的行为和视网膜电位反应

圆偏振光在地球环境中是很少见的, 来自珠宝金龟甲体壁反射圆偏振光是稀有的自然资源之一。铜绿丽金龟Anomala corpulenta Motschulsky与其他珠宝金龟甲一样其体壁能够反射左旋圆偏振光。为了解铜绿丽金龟对圆偏振光的感知能力, 本研究利用室内行为、 田间诱集与视网膜电位(electroretinogram, ERG)等方法研究了铜绿丽金龟对圆偏振光的响应。室内行为研究结果表明, 铜绿丽金龟对左旋圆偏振光与右旋圆偏振光的趋光反应明显低于非偏振光, 避光反应明显大于非偏振光, 且对左旋圆偏振光的趋、 避光反应均大于右旋圆偏振光。田间选择试验结果显示, 铜绿丽金龟对左旋和右旋圆偏振光的选择明显低于非偏振光, 且右旋大于左旋圆偏振光。电生理学研究结果表明, 左旋和右旋圆偏振光与非偏振光一样, 均能引发铜绿丽金龟的ERG反应, 且无明显差异。这些研究结果表明铜绿丽金龟体壁能够反射产生左旋圆偏振光, 且能够感知和区分左旋和右旋圆偏振光, 说明铜绿丽金龟存在偏振视觉, 具有圆偏振光敏感性。     

Phototaxis in stage i nauplius larvae of two cirripedes

The positive phototaxis of newly hatched, dark-adapted nauplius larvae, stage I, of Balanus balanoides (L.) and Elminius modestus Darwin has been investigated using interference filters with a narrow band transmission. The spectral sensitivity curve expressed in reciprocal μW/cm² required to give positive phototaxis shows a maximum between 520 and 530 nm and a marked shoulder at the shorter wavelengths. The number of photons/eye for threshold response has been calculated.     

A backflow of electrons around photosystem II in Chlorella cells.

A study was made with a modulated oxygen electrode of the effect of variations of oxygen concentration on photosynthetic oxygen evolution from algal cells. When Chlorella vulgaris is examined with a modulated 650 nm light at 22 degrees C, both the oxygen yield and the phase lag between the modulated oxygen signal and the light modulations have virtually constant values between 800 and 120 ergs . cm-1 . s-1 if the bathing medium is in equilibrium with the air. Similar results are obtained at 32 degrees C between 1600 and 120 ergs . cm-2 . s-1. Under anaerobic conditions both the oxygen yield and the phase lag decrease if the light intensity is lowered below about 500 ergs . cm-2 . s-1 at 22 degrees C or about 1000 ergs . cm-2 . s-1 at 32 degrees C. A modulated 706 nm beam also gives rise to these phenomena but only at significantly lower rates of oxygen evolution. The cells of Anacystis nidulans and Porphyridium cruentum appear to react in the same way to anaerobic conditions as C. vulgaris. An examination of possible mechanisms to explain these results was performed using a computer simulation of photosynthetic electron transport. The simulation suggests that a backflow of electrons from a redox pool between the Photosystems to the rate-limiting reaction between Photosystem II and the water-splitting act can cause a decrease in oxygen yield and phase lag. If the pool between the Photosystems is in a very reduced state a significant cyclic flow is expected, whereas if the pool is largely oxidized little or no cyclic flow should occur. It is shown that the effects of 706 nm illumination and removal of oxygen can be interpreted in accordance with these proposals. Since a partial inhibition of oxygen evolution by 3-(3.4-dichlorophenyl)-1,1-dimethylurea (10(-8) M) magnifies the decreases in oxygen yield and phase lag, it is proposed that the pool which cycles back electrons is in front of the site of 3-(3,4-dichlorophenyl)-1,1-dimethylurea inhibition and is probably the initial electron acceptor pool after Photosystem II.