长白鱼鳞云杉木材纹孔塞不同位置对渗透性的影响

通过对长白鱼鳞云杉（Picea jezoensis var.komarovii(V.Vassi.)Cheng et L.K.Fu)生材分别进行气干处理和酒精置换处理以及对其气干材进行水浸后再用酒精置换处理,研究了此３种处理方法形成不同的纹孔塞位置对木材渗透性的影响。结果表明,为材和心材的生材经气干处理后,其中边材的早材和晚材纹孔闭塞率增加至９９％和８１％,而心材因为其纹孔塞在立木时就已发生偏移,其早材和晚材纹孔闭塞率亦高,分别为９７％和８６％;由于其绝大多数纹孔塞保持中央位置,其中边材的早材和晚材纹孔塞闭率低,分别为８％和１７％,而心材因为绝大部分纹孔在立木时即已为关闭状态,酒精置换处理以降低其闭塞率无效,故其纹孔闭塞率高,分别为９７％和８６％;此种状态下边材和心材的气体渗透性分别为１１．７１３和０．０７４darcy,比普通气干处理状态下的渗透性分别增加１０１．５倍和６２．０％,t检验表明,前差异非常显,但后差异不显,气干材经水浸处理后再用酒精置换处理,其边材的早材和晚材纹孔闭塞率分别降低了１８％和２２％,心材分别降低了０和１７％;其气体渗透性分别为０．４３９和０．０６０darcy,较处理前分别增 ８５％和４９％,t检验表明差异均显。     

Effect of Different Positions of Bordered Pit Torus in Yezo Spruce on Its Permeability

The green wood of yezo species (Picea jezoensis var. komarovii (V. Vassil.) Cheng et L. K. Fu) was treated with air drying and ethanol exchange drying and by soaking the air-dried wood in water followed by ethanol change drying. The results showed that the proportion of aspirated pits in the respective earlywood and latewood of the air-dried sapwood was increased to 99% and 81%, while that of heartwood was also as high as 97% and 86% because most of the bordered pits were aspirated at its green state. The permeability of air-dried sapwood and heartwood was as low as 0.114 and 0.045 darcy respectively. The proportion of aspirated pits in the earlywood and latewood of sapwood after ethanol exchange drying was very low (8% and 17% respectively), whereas that of heartwood was very high (97% and 86% respectively) since most of the pits in it were aspirated at its green state, so the ethanol exchange drying failed to prevent pit aspiration. The permeability of sapwood and heartwood after ethanol exchange drying was 11.713 and 0.074 darcy respectivly, which was increased 101.5 times and 62.0% over the permeability at air-dried state. t-test showed that the difference of permeability of ethanol exchange drying versus air drying for sapwood was very significant at the level of 0.1%, but was not significant for heartwood. The proportion of aspirated pits in earlywood and latewood of air-dried sapwood and heartwood after soaking in water followed by ethanol exchange drying was decreased by 18% and 22%, and 0 and 17%, respectively, while the permeability of sapwood and heartwood was 0.439 and 0.060 darcy respectively, which was increased by 85% and 49% respectively. The permeability difference of soaking sapwood and heartwood versus their controls was very significant at the 0.1% level by t-test.     

Bordered pits in xylem of vesselless angiosperms and their possible misinterpretation as perforation plates

Vesselless wood represents a rare phenomenon within the angiosperms, characterizing Amborellaceae, Trochodendraceae and Winteraceae. Anatomical observations of bordered pits and their pit membranes based on light, scanning and transmission electron microscopy (SEM and TEM) are required to understand functional questions surrounding vesselless angiosperms and the potential occurrence of cryptic vessels. Interconduit pit membranes in 11 vesselless species showed a similar ultrastructure as mesophytic vessel‐bearing angiosperms, with a mean thickness of 245 nm (± 53, SD; n = six species). Shrunken, damaged and aspirated pit membranes, which were 52% thinner than pit membranes in fresh samples (n = four species), occurred in all dried‐and‐rehydrated samples, and in fresh latewood of Tetracentron sinense and Trochodendron aralioides. SEM demonstrated that shrunken pit membranes showed artificially enlarged, > 100 nm wide pores. Moreover, perfusion experiments with stem segments of Drimys winteri showed that 20 and 50 nm colloidal gold particles only passed through 2 cm long dried‐and‐rehydrated segments, but not through similar sized fresh ones. These results indicate that pit membrane shrinkage is irreversible and associated with a considerable increase in pore size. Moreover, our findings suggest that pit membrane damage, which may occur in planta, could explain earlier records of vessels in vesselless angiosperms.     

Neuronal Substrates for Infrared Contrast Enhancement and Motion Detection in Rattlesnakes

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AN EXPANDED SURVEY OF THE ULTRASTRUCTURE OF RED ALGAL PIT PLUGS1

The fine structure of pit plugs in 90 species of red algae was examined, bringing the total number of species in the continuing survey to 153. The organization of plug caps was confirmed to be a stable, predictable trait within thalli, between generations in heteromorphic life histories, and within the presently recognized orders, with one exception—the Acrochaetiales. Two forms of the outer cap were found in this group, a thin plate, as in the Nemaliales and Palmariales, and a dome, as in Batrachospermales and Corallinales. Variation of pit plug structure indicates that the Acrochaetiales are a heterogeneous assemblage and that pit plugs will be useful in reappraising their systematics. The systematic affinities of several species of uncertain affinities are clarified. Schmitziella endophloea Bornet et Batters is excluded from both orders, Corallinales and Acrochaetiales, with which it previously was allied. Although other ordinal attributions are not precluded by pit plug structure alone, pit plug structure is consistent with placement of Apophlaea sinclairii Harvey and Hildenbrandia rivularis (Liebman) J. Agardh in the Hildenbrandiales, Plagiospora gracilis Kuckuck, Schmitziella endophloea, and Wurdemannia miniata (Duby) J. Feldmann et Hamel in the Gigartinales, and Pseudorhododiscus nipponicus Masuda in the Palmariales.     

窖泥群落结构及功能微生物研究进展

窖泥是浓香型白酒的特征发酵载体,包含多种功能微生物,这些功能微生物对浓香型白酒的风格特征和品质有着重要的影响。本文对不同窖龄窖泥、不同浓香型白酒产地的窖泥及不同质量窖泥的窖泥微生物研究进展进行总结分析,并在此基础上对窖泥主体微生物的功能进行阐述。以期为窖泥微生物的研究提供思路,为浓香型白酒的质量和香味成分研究提供思考,促进窖泥微生物的研究,加深对浓香型白酒窖泥的认知。     

ABSENCE OF CAP MEMBRANES AS A CHARACTERISTIC OF PIT PLUGS OF SOME RED ALGAL ORDERS1

The current general model of the organization of a fully developed rhodophycean pit plug includes a cap membrane associated with each end of the plug. Continuity of the plasmalemma and cap membrane results in the plug core being extracellular. However, routine ultrastructural methods have not convincingly demonstrated cap membranes in the Bangiales or the Corallinales. In this study, a variety of fixation regimes that enhance membrane contrast were used in an attempt to detect cap membranes in representatives of these two orders. Although cap membranes were readily and clearly demonstrable by these methods in a representative of an order previously known to have cap membranes, they could not be detected in members of the Bangiales or Corallinales. Should the absence of cap membranes prove to be an invariant feature of these two orders, presence or absence of cap membranes will constitute a new character for phylogenetic analysis. It is proposed that the ancestral character state of red algal pit plugs was a homogeneous plug without caps and without cap membranes.     

ABSENCE OF CAP MEMBRANES AS A CHARACTERISTIC OF PIT PLUGS OF SOME RED ALGAL ORDERS1

The current general model of the organization of a fully developed rhodophycean pit plug includes a cap membrane associated with each end of the plug. Continuity of the plasmalemma and cap membrane results in the plug core being extracellular. However, routine ultrastructural methods have not convincingly demonstrated cap membranes in the Bangiales or the Corallinales. In this study, a variety of fixation regimes that enhance membrane contrast were used in an attempt to detect cap membranes in representatives of these two orders. Although cap membranes were readily and clearly demonstrable by these methods in a representative of an order previously known to have cap membranes, they could not be detected in members of the Bangiales or Corallinales. Should the absence of cap membranes prove to be an invariant feature of these two orders, presence or absence of cap membranes will constitute a new character for phylogenetic analysis. It is proposed that the ancestral character state of red algal pit plugs was a homogeneous plug without caps and without cap membranes.     

中国裸子植物木材具缘纹孔构造类型的研究

根据100种中国裸子植物木材(隶属4纲、8目、11科,42属)具缘纹孔构造的研究,提出8种不同具缘纹孔类型:1.苏铁型;2.南洋杉 A 型;3.南洋杉 B 型;4.落羽杉 A 型;5.落羽杉 B 型;6.松木 A 型;7.松木 B 型;8.买麻藤型。A 型是指纹孔室内瘤状层缺乏或罕见,B型则具明显的瘤状层。并对具缘纹孔在系统发育中的变化进行了讨论。     

Foraging in the ant-lionMyrmeleon mobilis hagen 1888 (neuroptera: Myrmeleontidae): Behavioral flexibility of a sit-and-wait predator

The relative effects of foraging benefits (food intake) and costs (disturbance = pit destruction) on growth rate and foraging behavior of larvae of the ant-lionMyrmeleon mobilis were investigated. In a laboratory experiment second-instar larvae were subjected to combinations of three rates of feeding and three rates of disturbance. Pit relocations were generally rare but occurred more often in starved larvae. Disturbance rate had no significant effect on pit relocation rate. Feeding rate was a major determinant of the energy allocated in pit construction and maintenance (positive relationship). In a second experiment third-instar larvae encountered changing rates of disturbance. Pit size was reduced as a response to increased rates of disturbance. Disturbance had no detectable effect on growth. In general,M. mobilis larvae were cost-conservative, foragers.     

Perforated pit membranes in imperforate tracheary elements of some angiosperms

BACKGROUND AND AIMS: The structure of pit membranes in angiosperms has not been fully examined and our understanding about the structure is incomplete. Therefore, this study aims to illustrate the micromorphology of pit membranes in fibres and tracheids of woody species from various families. METHODS: Specimens from ten species from ten genera and eight families were prepared using two techniques and examined by field-emission scanning electron microscopy. KEY RESULTS: Interfibre pit membranes with an average diameter of <4 microm were frequently perforated or appeared to be very porous. In contrast, pit membranes in imperforate tracheary elements with distinctly bordered pits and an average diameter of >or=4 microm were homogeneous and densely packed with microfibrils. These differences were observed consistently not only among species but also within a single species in which different types of imperforate tracheary elements were present. CONCLUSIONS: This study demonstrates that the structure of interfibre pit membranes differs among cell types and the differences are closely associated with the specialization of the fibre cells. It is suggested that perforated pit membranes between specialized fibres contribute to the dehydration of the fibre cells at or soon after maturation.     

Determination of the trophic state by qualitative and quantitative phytoplankton analysis in two gravel pit lakes

The phytoplankton of two gravel pits with comparable nutrient concentrations but different chlorophyll-a concentrations and phytoplankton biovolume was investigated qualitatively and quantitatively over a period of two years. This study deals with the phytoplankton-rich ‘Rotter See’ and the phytoplankton-poor ‘Paulsmaar’, both South of Cologne. The trophic state of both lakes was determined comparatively according to Ryding &; Rast (1989) and the categories used by Brettum (1989). The results were compared with each other. The trophic lake index according to Hörnström (1981) was modified slightly and subsequently determined for both lakes. A combination of qualitative and quantitative phytoplankton analysis made a proposal of a rehabilitation for the Rotter See possible.     

Distribution, Ecology and Population Dynamics of the American Burying Beetle [Nicrophorus Americanus Olivier (Coleoptera, Silphidae)] in South-central Nebraska, USA

The endangered American burying beetle, Nicrophorus americanus Olivier, was previously widespread throughout eastern North America. In the past century numbers of this beetle have drastically declined and currently remnant populations are known from only six states despite intensive surveying efforts conducted for the last nine years. Efforts aimed at discovering and managing remnant populations have been generally limited by a lack of knowledge concerning N. americanus biology. We used baited pitfall traps to define the range of the Gothenburg, Nebraska population of N. americanus. Using mark-recapture techniques, we estimate that the annual Gothenburg population consists of more than one thousand individuals, meeting the recovery plan criterion to become the third breeding population in the Midwest region. Beyond estimates of population size and range, we present novel data on seasonal and daily activity, sex ratio, age-grading and foraging distances. In 1995 and 1996, the Nebraska population was univoltine and female biased, with over-wintering mature beetles emerging in early June and teneral beetles emerging in August. Nocturnal activity was highest in the third and fourth hours following sunset but was not strongly correlated with temperature. During foraging, beetles travel up to six kilometers, but the majority of our recaptures occurred at distances of less than 0.5 km, suggesting that distances between traps be increased to ensure independence of sampling units. This information will allow future work on captive breeding, re-introduction and genetic studies.     

领春木(领春木科)导管穿孔板中纹孔膜残余的观察

对领春木(Euptelea pleiospermum Hook.f．et Thoms．)次生木质导管穿孔板上穿孔中纹孔膜残留的观察表明,纹孔膜的残留非常丰富,类型多样,包括从接近具有完整的纹孔膜到基本完全消失的纹孔膜之间存在着连续的过渡类型。根据观察结果认为,领春木次生木质部中的导管可能代表了一种系统发育过程中的原始或过渡状态,因此领春木科也应该是一个比较原始的木本双子叶类群。     

Is That Dog a Pit Bull? A Cross-Country Comparison of Perceptions of Shelter Workers Regarding Breed Identification

Bull breeds are commonly kept as companion animals, but the pit bull terrier is restricted by breed-specific legislation (BSL) in parts of the United States and throughout the United Kingdom. Shelter workers must decide which breed(s) a dog is. This decision may influence the dog's fate, particularly in places with BSL. In this study, shelter workers in the United States and United Kingdom were shown pictures of 20 dogs and were asked what breed each dog was, how they determined each dog's breed, whether each dog was a pit bull, and what they expected the fate of each dog to be. There was much variation in responses both between and within the United States and United Kingdom. UK participants frequently labeled dogs commonly considered by U.S. participants to be pit bulls as Staffordshire bull terriers. UK participants were more likely to say their shelters would euthanize dogs deemed to be pit bulls. Most participants noted using dogs' physical features to determine breed, and 41% affected by BSL indicated they would knowingly mislabel a dog of a restricted breed, presumably to increase the dog's adoption chances.     

Brain – Hatschek's pit relationships in amphioxus species

The vertebrate hypothalamo-hypophyseal neurosecretory system is a complex anatomical device for central nervous control over secretion of pituitary hormones. Since it is present in the most primitive vertebrates, the cyclostomes, it is of interest to look for a possible invertebrate anatomical equivalent, or precursor, for clues as to its evolution. We have found in six species of amphioxus, members of an invertebrate group (cephalochordates), considered to be closest to the vertebrates, that there is a morphologically equivalent neuro-epithelial complex, that in many ways resembles the hypothalamo-hypophyseal system of vertebrates. In the six amphioxus species described here the nervous element is a ventral lobe of the brain, the infundibulum, that extends downward along the right side of the notochord, and ends near the dorsal surface of a Rathke's pouch-like structure known as Hatschek's pit. This part of Hatschek's pit has been found earlier to contain a vertebrate LH-like gonadotropin. Therefore, the infundibulum-Hatschek's pit system of amphioxus may be involved in regulating the seasonal reproductive cycle, and it appears to be a direct homologue of the vertebrate hypothalamo-hypophyseal neurosecretory system functionally as well as morphologically.     

广西野生蔗及其近缘植物营养器官内部结构的初步研究

广西野生蔗及其近缘植物营养器官内部结构基本相同。但割手密叶片下表皮具有明显的气孔窝斑茅等则无。斑茅茎节间的维管束分布较均匀,河八王茎中央没有维管束分布,割手密与蔗茅茎中维管束的分布。居于二者之间。