编写《微生物学教程》有感

《微生物学教程》获"首届全国教材奖"(二等奖)的消息后,为响应学院领导提出的总结、交流等要求,特撰写了本文.作者以"愿终生能炼成一个称职的微生物学教师"为指导思想,历经半个多世纪的努力,在教书育人的同时,编写了较多的文章和书籍,其中的代表作当属《微生物学教程》.该书至今已出了 4版,被300余所高等院校选作教材,总印数...     

The nature and role of learning in the orientation and migratory behavior of fishes

Synopsis Fish migration may be viewed as the product of two processes; the selection and tracking of optimal environmental conditions through time and space, and the use of predictive information about environmental structure to bias movements towards a goal. The establishment and maintenance of directional bias is based on the interaction of experience and instinct. The preoccupation of much fish orientation research with innate fixed patterns of behavior on one hand and hydrodynamics on the other has led us to underestimate the possibility that orientation is a flexible process relying on developmental sequences, calibration of the motor-sensory interaction based on experience and the learning of environmental pattern. Evidence illustrating how experience and learning may influence the direction of movement and how the goal is recognized is presented according to two general categories: (a) imprinting and early experience and (b), spatial learning, including the social transmission of migratory routes and directions. In the first category, the olfactory hypothesis of salmon homing is briefly reviewed and new data presented describing olfactory imprinting in Atlantic salmon,Salmo salar. In the second category, evidence is presented demonstrating the modifiability of sun-compass orientation and the ability of some fish species to learn the spatial distribution of landmarks. The role of social transmission in the migration of coral reef fishes is reviewed. The possible role of these learning phenomena in the formation of familiar area maps, route-based and location-based navigation and the critical distance factor is considered. The relationship between life history and the nature of learning in migratory orientation is discussed     

Effects of search experience in a resource-heterogeneous environment on the oviposition decisions of the seed beetle, Callosobruchus maculatus (F.)

Abstract.  1. This study investigates how female seed beetles, Callosobruchus maculatus , distribute their eggs on various-sized seeds when the size of seed was varied during the egg-laying period.
2. Beetles were allowed to lay eggs on one of three arrays of 64 adzuki beans ( Vigna angularis ). Each array contained four size classes of seed, ranging from small (5.0–5.5 mm diameter) to large (6.5–7.0 mm), but differed in how they were distributed within the environment. In the most heterogeneous condition (the 64-patch design), the four sizes were interspersed, while in the least heterogeneous condition (the four-patch design) they were grouped into four separate blocks. Thus, a beetle exploring the 64-patch design would frequently encounter all four seed sizes, whereas a beetle exploring the four-patch design would only rarely encounter a change in bean size.
3. Beetles experiencing greater seed size heterogeneity were more likely to lay eggs on larger seeds, whereas those in the blocked condition were more likely to oviposit on small seeds. Beetle responses to seed size heterogeneity suggest that the degree of preference for large seeds depends on a female's recent experience.
4. Female beetles exhibited size discrimination throughout their egg-laying process; however, there was a trade-off between seed size and egg discrimination (i.e. avoiding those seeds already containing developing eggs) in response to the change in fitness gained from either laying on larger seeds or lower egg-load seeds during the egg-laying process.
5. Our model provides the first evidence that evolving seed size discrimination ability is adaptive for the seed beetle with egg-discrimination ability.     

How many footsteps do dogs need to determine the direction of an odour trail?

Dogs have the ability to determine the direction of an odour trail left by a human. This study examined how much olfactory information from this trail is required by dogs to determine direction. Six dogs, able to determine direction, were tested on a 21 footstep trail laid on 21 individual carpet squares, one footstep per square, by the same individual wearing the same shoes. Dogs brought in at right-angles to the trail at its centre were able to correctly determine direction better than chance (P < 0.025). Dogs were unable to determine direction when the order of the footsteps was randomized by rearranging the order of the carpet squares. When the individual odour cue was removed, but ground disturbance left, dogs were unable to determine direction, indicating that it was the odour of the individual that was used to determine direction. In the final experiment the number of footsteps made available to the dog was reduced from 21 to 11 and then 9, 7, 5 and finally 3. Dogs were able to determine direction from 5 footsteps but not 3. It was calculated that it takes approximately 1-2 s for the odour information in footsteps to change to provide discernible information that can be used by dogs to determine direction. The process by which dogs may determine direction from odour cues is discussed.     

Detection of non-pylori Helicobacter species in "Helicobacter heilmannii"-infected humans

BACKGROUND: A small proportion of patients suffering from chronic active gastritis are diagnosed with gastric Helicobacter species other than Helicobacter pylori. Circumstantial evidence has suggested that these bacteria, also referred to as "Helicobacter heilmannii"-like organisms (HHLO), may be transmitted through animals. The isolation of a Helicobacter bizzozeronii strain from a human patient confirmed this hypothesis. It was the aim of the present study to assess the presence of animal Helicobacter species and H. pylori in humans infected with HHLO, as diagnosed by histology. METHODS: Paraffin-embedded gastric biopsy specimens of 108 HHLO-infected patients (42 women and 66 men) from three clinical centers were screened for the presence of animal gastric Helicobacter species by polymerase chain reaction (PCR), using assays targeting the 16S rDNA region of the three known canine and feline helicobacters (H. bizzozeronii, H. salomonis and H. felis), "Candidatus H. suis", and "Candidatus H. bovis". In addition, the presence of H. pylori was evaluated by multiplex PCR analysis. RESULTS: In 63.4% of the stomachs (64/101) classification of the Helicobacter infection into the above mentioned groups was achieved. Non-pylori Helicobacter species commonly colonizing the stomachs of cats and dogs were found in 48.5% (49/101) of the patients. Fourteen (13.9%) samples tested positive for "Candidatus H. suis", and "Candidatus H. bovis" was demonstrated in 1 (0.9%) patient. The presence of H. pylori was established in 13 patients (12.9%). Eleven stomachs (10.9%) were infected with at least two different Helicobacter species. CONCLUSIONS: This study identifies animal Helicobacter species in the stomach of a large series of HHLO-infected patients, which may have clinical implications in a subset of patients with gastric disease.     

Jumping spiders attend to context during learned avoidance of aposematic prey

A large number of studies on both animals and humans have demonstratedthat learning is influenced by context or secondary cues thatare present when an association is formed. Few studies, however,have examined the functional value of attending to context.We first demonstrated that jumping spiders, Phidippus princeps,could be trained to avoid aposematic, distasteful milkweed bugs,Oncopeltus fasciatus. Spiders readily attacked bugs on firstexposure but were significantly less likely to do so after eighttrials, although they subsequently attacked and ate crickets.Spiders exposed to nontoxic milkweed bugs reared on sunflowerseeds did not show the same decline in attack rate. We nextexamined the effects of secondary contextual cues on spiderlearning by training spiders to avoid milkweed bugs in one oftwo environments. When spiders were tested in an environmentdifferent from the one in which they were trained, attack ratesincreased, and spiders no longer demonstrated retention of theassociation. Spiders tested in the same environment in whichthey were trained continued to avoid attacking the bugs. Theseresults have potential consequences for the evolution of bothpredator and prey and point to the importance of studying context-dependentlearning.     

First record of the raccoon dog (Nyctereutes procyonoides Gray, 1834) in the former Yugoslav Republic of Macedonia

An adult male raccoon dog (Nyctereutes procyonoides Gray, 1834) run over by a car was found on September 6, 2002, in the central part of the Former Yugoslav Republic of Macedonia (UTM: EM 54). This is the first record of this species on the territory of the FYRM, and the southernmost point of its European range so far. This finding indicates a range extension of the raccoon dog on the Balkan Peninsula.     

Suppressive effect of exposure to Chenopodium album var. centrorubrum on the feeding response of the tortoise beetle, Cassida nebulosa, to spinach

Depending upon preceding dietary exposure, the tortoise beetle, Cassida nebulosa L. (Coleoptera: Chrysomelidae), exhibits various feeding responses to spinach, Spinacia oleracea L. (Chenopodiaceae). Adult tortoise beetles reared as adults on the main host Chenopodium album var. centrorubrum Makino (CAC) (Chenopodiaceae) eat little spinach, whereas those reared on spinach accept this plant as food. In this study, we investigated the suppressive effect of exposure to CAC on the feeding response of tortoise beetles to spinach. To investigate the effect of chemical factors in CAC, we provided beetles with Gomphrena globosa L. (Amaranthaceae) as the base food and exposed them to a CAC extract, because bioassays have indicated that exposure to G. globosa did not affect the feeding response of beetles to spinach. Adults reared on G. globosa treated with CAC extract consumed significantly less than adults reared on untreated G. globosa . Thus, we determined that exposure to CAC components is responsible for the suppressive effect on the feeding response to spinach observed in the beetles. In a choice feeding test with membrane filter discs, we found that adults reared on G. globosa treated with CAC extract exhibited a greater feeding deterrent response to the spinach deterrent than adults reared on untreated G. globosa leaves. Therefore, the suppression of spinach consumption due to exposure to CAC is probably caused by the development of a response to the feeding deterrents present in spinach.