雪霸公园雪山主峰线之承载量研究

本研究之目的在于取得雪山主峰线登山步道最适承载量计量值,以供雪霸公园管理处日后进行承载量管理之参考。研究结果表明,就社会心理承载量而言,登山者对于同时进行登山活动者的承载程度为11-40人或甚至可以更多;实质的设施承载量则依据雪山主峰线目前现况设施可容纳的最大登山人数为296人;每日最大实质生态承载量于平常日为109人,公休日以不超过218人为宜。稀有生物繁殖期最好禁止登山者入山,若无可避免时,每日以不超过65人为宜。本研究建议后继研究应进行长期游憩冲击所带来的环境影响程度的监测,每三年或五年再检查一次生态资料的变化,或有稀有动、植物的消长,配合长期游憩冲击监测指标,以适时修正承载量管制的人数,适度地调整登山人数。     

Trail Communication During Foraging and Recruitment in the Subterranean Termite Reticulitermes santonensis De Feytaud (Isoptera, Rhinotermitidae)

The search for food in the French subterranean termite Reticulitermes santonensis De Feytaud is organized in part by chemical trails laid with the secretion of their abdominal sternal gland. Trail-laying and -following behavior of R. santonensis was investigated in bioassays. During foraging for food termites walk slowly (on average, 2.3 mm/s) and lay a dotted trail by dabbing the abdomen at intervals on the ground. When food is discovered they return at a quick pace (on average, 8.9 mm/s) to the nest, laying a trail for recruiting nestmates to the food source. While laying this recruitment trail the workers drag the abdomen continuously on the ground. The recruitment trail is highly attractive: it is followed within a few seconds, by more nestmates, and at a quicker pace (on average, 6.4 mm/s) than foraging trails (on average, 2.9 mm/s). The difference between foraging and recruitment trails in R. santonensis could be attributed to different quantities of trail pheromone. A caste-specific difference in trail pheromone thresholds, with workers of R. santonensis being more sensitive to trails than soldiers, was also documented: soldiers respond only to trails with a high concentration of trail pheromone.     

Rediscovery of the workerless inquiline antPogonomyrmex colei and additional notes on natural history (Hymenoptera: Formicidae)

Summary Pogonomyrmex colei is a workerless inquiline ant known only from nests ofP. rugosus, its closest relative. Ten of 776 (1.3%) host nests were parasitized at a site in central Arizona, while none of 1499 potential host colonies were parasitized at two other locales. Colonies ofP. colei are perennial, and host alate females in 9 of 10 colonies demonstrates that host queens survive parasitism. Three of 10 colonies died over 19 colony years of observation, while only 1 of 601 colonies became newly parasitized. Mating occurs in morning for up to 2–3 days following summer and fall rains and in afternoon during cool fall days. Mating is intranidal just outside the nest entrance, with males returning to the natal nest. MaleP. colei may be flightless because their wing area is reduced compared to host males. Females fly from the nest and locate potential host colonies by following trunk trails. Workers are the largest barrier to nest establishment, as they removed over 90% ofP. colei females placed in trunk trails or that entered host nests. Males and females ofP. colei andP. anergismus, the only other congeneric inquiline species, are diminutive compared to their hosts, with females 30% lighter than host workers. Fat content is lower and water content is higher inP. colei andP. anergismus females than in their hosts.     

Keratin-like components of gland thread cells modulate the properties of mucus from hagfish (Eptatretus stouti)

Summary The hagfishes (cyclostomes) are known to secrete copious amounts of mucus mainly by the holocrine mode from the slime glands. Stressed animals release two types of cells (gland thread cells, GTCs; gland mucous cells, GMCs) which rupture on contact with water and rapidly form a mass of viscous mucus. Herein we report some key sequential events of this process and document a novel role for cytoskeletal polymers. After electrostimulation of Pacific hagfish (Eptatretus stouti), the exudate was collected in a stabilization buffer and GTCs segregated from GMC vesicles. Water was added progressively to mixtures of known quantities of these entities. The changing mucous composition and properties were monitored by light- and electron microscopy, viscometry and immunogold assay. Sequentially, the threads uncoil from GTCs, aggregate with the vesicles, the vesicles rupture and release mucin-like substances, at least some of which adhere to the thread. It was found that the intermediate filament (IF)-rich threads markedly facilitate hydration and modulate the viscoelastic and cohesive properties of the resultant mucus. It was speculated that the thread abets localization of mucus in an aqueous environment and promotes adhesion of mucus to surfaces such as the fish integument. As judged by immunostaining in situ, GTCs, as well as several cell-types in the epidermis, contain keratin-like components. The role of biopolymers on the properties of teleost and mammalian mucus is discussed.     

Ultrastructure and permeability characteristics of the membranes of mucous granules of the hagfish

Mucous granules secreted by the slime glands of the hagfish. Eptatretus stouti, were studied after ultrarapid cryofixation and freeze substitution in diverse media (osmium tetroxide in acetone; several aqueous glutaraldehyde-based media with or without osmium). Only freeze substitution with osmium tetroxide-acetone preserved the granules intact, allowing visualization of its single unit membrane. Tests of the rupture or stability of freshly secreted mucous granules in sea water and other aqueous media showed the membranes of the granules are permeable to all inorganic cations tested, ranging in relative mass from ammonium to barium. They are permeable to the univalent anions chloride, nitrate, and bicarbonate, but not to the di- or trivalent anions sulfate, phosphate, and citrate. Moreover, in solutions where nonpenetrant anions were present, rupture occurred if the osmotic pressure was below a critical level (about 800 mOsmol/l). The structural and permeability characteristics of the granules account for the explosive speed with which they rupture, releasing their mucous contents, on contact with sea water.     

Schistosoma mansoni: histochemical analysis of the postacetabular gland secretion of cercariae

Contents of the funduses and ducts of the postacetabular glands of Schistosoma mansoni cercariae, the secreted deposits, and the surface film were compared by their histochemical reactions. Techniques for carbohydrate-containing substances, neutral and acid mucosubstance, proteins and amino acids, and enzymes were used. The secretion reacted differently before (within the glands) and after (in secreted deposits) emission.Before emission, the postacetabular gland contents reacted as a neutral mucosubstance containing periodate-engendered and periodate-reactive aldehydes rich in vic-glycols or their substituted amines, probably hexoses other than glucose, such as fucose or galactose. No reactions of significance were observed for acid groups or for glycogen or lipids. In this state, the secretion is termed mucigen.After emission, the secretion stained not only as mucigen, but also as acid mucosubstance, apparently sialomucin. After emission, it is termed mucin.It is probable that acid radicals were present in mucigen but were masked stearically by the presence of adjacent neutral radicals or basic proteins. The surface film reacted as both a neutral and an acid mucosubstance. Evidence suggested that the film itself was neutral and that the reaction for acid mucosubstance was from an overlay of mucin secreted from the postacetabular glands.Proteins and amino acids, especially arginine, and some tyrosine and tryptophan were indicated in mucigen and in mucin by the histochemical tests. There was no histochemical evidence of enzymes. Secretion of the postacetabular glands is concluded from histochemical reactions, as from earlier chromatographic data (Stirewalt and Evans 1960), to be a carbohydrate-protein-lipid complex.     

Surface changes during development and involution of the cement gland of Xenopus laevis

Summary The cement gland was studied from stage 17, when the anlage is established, to stage 49, shortly before its disappearance. At early stages, the apical membrane is covered by small microvilli that are more abundant than in the surrounding epiblast cells. Vesicular protrusions along the cell boundaries are also more numerous in the gland cells.When the gland reaches maturity, the apical membranes of gland cells differentiate into two regions. In the cranial, kidney-shaped region, the membranes are very narrow and protrude above the level of cell boundaries. Long and slender villi raise from the surface adjacent to cell boundaries. Apical surfaces in the caudal portion are larger and flattened. Cell boundaries are lined with shorter and thicker surface projections. At these stages, the bordering cells are covered with secretion vesicles.During involution the number of cells is progressively reduced. The area of the caudal portion increases relative to the area of the cranial portion. Apical surfaces become more flattened. Surface projections become much shorter and invade the whole of the apical surface. Bordering cells lose their secretion vesicles and their apical surface becomes ruffled with numerous short wrinkles. The significance of the apical structures and their evolution is discussed.     

Social Cues and Following Behavior in the Forest Tent Caterpillar

Colonies of the social caterpillar Malacosoma disstria Hubner (Lepidoptera: Lasiocampidae) travel in groups following silk trails marked with pher-omone. This study examined first, the cues involved in following behavior and second, the responses to these cues at different larval stadia. Both second and fourth instar larvae discriminated between fresh and older trails, and travelled faster in the presence of trails. In addition to trail following, young caterpillars exhibited leader following, which might be particularly important in exploring unmarked territory. Indeed, second instar caterpillars were more likely to travel together when trails were absent. Fourth instar larvae exhibited greater independent locomotion in the absence of trails than did younger larvae. These findings help explain patterns of social behavior observed in forest tent caterpillar colonies in the field.     

Fungistatic activity of the sternal gland secretion of the dampwood termite <Emphasis Type="Italic">Zootermopsis angusticollis</Emphasis>

Summary In vivo and in vitro studies indicate that cuticular chemicals from the ventral region of the abdomen where the sternal gland of the dampwood termite Zootermopsis angusticollis is located have fungistatic properties. Germination rates of conidia of the entomopathogenic fungus Metarhizium anisopliae were significantly reduced from 91% (controls) to 38.5% after nymphs walked over conidia-seeded agar medium, but did not differ from controls when the sternal gland and surrounding cuticle were sealed with nail polish. In vitro studies show that germination of fungal conidia was also significantly reduced following incubation with cuticular extracts of either sternal or tergal segments suggesting that cuticular exudates in general may have antifungal properties. Extracts of sternites had greater fungistatic activity than extracts of tergites, but the difference was not statistically significant. Extracts of the sternal gland significantly reduced germination rates by up to 9%. Germination rates were significantly reduced when conidia were incubated with n-hexanoic acid, or its vapor. n-Hexanoic acid has been recovered from whole body extracts of Zootermopsis nevadensis and may indeed be a component of the sternal gland of Z. angusticollis. Here we suggest that sternal gland secretions in termites may have had the original function of controlling microbes within the nest and their prominent role in communication may have evolved secondarily.Received 18 April 2003; revised 20 November and 17 December 2003; accepted 19 January 2004.     

A comparative study of the ultrastructure of the water-blood pathway in the secondary lamellae of teleost and elasmobranch fishes — benthic forms

Summary The ultrastructure of the secondary lamellae has been examined in four species of free-swimming elasmobranchs, two species of Raia and five species of bony flatfishes. Microvilli which are present on the outer epithelial surface vary in form and size. It is suggested that a possible function of the microvilli is to anchor a surface mucus covering whose possible functions are discussed. Vesicles are found immediately beneath the microvilli in elasmobranchs but not in teleosts. Chloride and mucous cells are present on the secondary lamellae of all species and often have microvilli of greater length than on the other cells of the epithelium. Micropinocytotic vesicles are found on both sides of the basement membrane. The number of columns enclosed in the pillar cells varied from 5–11.The water-blood pathway showed variations in thickness not only between different species but also in different parts of individual secondary lamellae. A general trend in the mean total thickness was found, being greater in the swimming elasmobranchs (10.22 ) than in the rays (5.47 ) and bony flatfish (3.59 ). This trend is also seen in the greater length of microvilli and thickness of basement membrane in the elasmobranchs than in the teleosts.