Respiration and Circulation in Land Crabs: Novel Variations on the Marine Design

Both the "true" crabs (Brachyura) and hermit crabs (Anomura)include species that show numerous behavioral, morphological,and physiological specializations permitting terrestrial life.This paper examines respiratory and circulatory adaptationsfor air breathing in these land crabs. Respiratory specializationsinclude modification of gas exchange structures for air breathing(gills and elaborated branchial chamber linings), ventilatorymechanisms permitting effective air pumping, an elevated hemolymphoxygen capacity, and a primarily CO₂- rather than O₂- sensitiveventilatory control system. The qualitative aspects of hemolymphoxygen transport and metabolic rate are apparently unchangedfrom that of marine crabs. While the basic cardiovascular morphologyof land crabs appears similar to that of marine forms, thereis considerable elaboration of the vasculature of the branchialchamber lining, which in some species includes a unique doubleportal system. Cardiac output is lower in land crabs (probablyrelated to their higher hemolymph O₂ capacity), but insufficientdata on hemolymph pressures prevent comparisons with marineforms. In general, land crabs have modified (sometimes extensively)existing structures and processes found in their marine relativesrather than evolving structures for terrestrial life de novo.Accordingly, land crabs present a useful model for the evolutionof terrestriality, showing that even subtle anatomical changescan result in the large changes in physiological function necessaryfor the terrestrial invasion.     

The ultrastructure of the book lungs of the Italian trap-door spider Cteniza sp. (Araneae,Mygalomorphae, Ctenizidae)

The fine structure of book lungs is not homogeneous across Arachnids and is considered phylogenetically informative, however few reports on the ultrastructural features of this organ have been published. In this study, we examined the general morphology and ultrastructure of adult spiders of the genus Cteniza. The respiratory system of Cteniza sp. consists of two pairs of well-developed book lungs, which is considered indicative of primitive spiders. The general organization of the book lungs is similar to that described for other arachnids and consists of leaves of alternating air and hemolymph channels. The air channels are lined with cuticle and open to an atrium that leads to a slit-like spiracle. The air channels are held open by cuticular trabeculae. The space holders in the hemolymph channels are pillar trabeculae formed by two cells from the opposed walls. The pillar cells have a complex ultrastructure that includes an interdigitating connection, gap junctions, microtubules and hemidesmosomes. These features apparently help strengthen the pillar cells and their interconnections with each other and the underlying cuticle. The cytoskeleton resembles that of arthropod tendon cells where substantial structural support is needed.     

Venous air embolism during a craniofacial procedure

The possibility of venous air embolism exists whenever the craniofacial operative field is above the level of the heart. Craniotomy with the high-torque craniotome is hypothesized to have produced venous air embolism in the patient described in this report. The diagnosis of venous air embolism is determined by transesophageal Doppler probe, transesophageal echocardiogram or external echocardiogram, and end-tidal N2 and CO2 determinations. Treatment includes control of the air entry sites, aspiration of air from the right atrium via a catheter placed prior to operation, and discontinuing nitrous oxide. If these measures are unsuccessful, the operative field should be transposed below heart level and the procedure terminated. In the event of significant hemodynamic compromise, closed cardiac massage should be tried; if that fails, open cardiac massage and direct aspiration are necessary. The true incidence of venous air embolism in craniofacial operations may be much higher than previously suspected. We therefore recommend placement of appropriate monitoring equipment to detect intracardiac air in those major craniofacial procedures in which there is a potential for intravascular air ingress.     

Evidence for air movement signals in the agonistic behaviour of a nocturnal arachnid (order Amblypygi)

Many arthropods possess filiform hair sensilla (termed trichobothria in arachnids), which are extremely sensitive detectors of medium particle displacement. Electrophysiological evidence in some taxa suggests that these sensilla can detect air particle displacements resulting from intraspecific communication signals. However, it has not yet been shown for any species that the air particle displacements detected by the filiform hairs are themselves perceived as a 'signal' (i.e. that individuals make behavioural decisions based upon the responses of these organs to the displays of conspecifics). We investigate the agonistic behaviour of the whip spider Phrynus marginemaculatus and the role of its trichobothria in receiving agonistic signals. Whip spiders have extremely elongated 'antenniform' first legs, which they vibrate close to their opponents during agonistic interactions, inducing air movements that excite their opponents' trichobothria. We find that ablation of the trichobothria causes significant increases in: (I) contest duration, and (II) the probability of contest escalation past aggressive displays to physical fighting. Therefore, in the absence of air movement-sensitive sensilla, contest assessment is impaired. This suggests that whip spiders exploit true air movement signals during agonistic interactions, and that these are received by the trichobothria. Furthermore, these results indicate that, in whip spiders, such signals help mitigate the cost of agonistic interaction.     

鳅鮀鱼类鳔囊结构及系统发育研究(鲤形目:鲤科)

本文应用分支系统学原理对鳅(鱼它)鱼类的鳔囊、鳔及相关结构进行了特征分圻,并以(鱼句)亚科作为外类群。解剖结果表明,鳅(鱼它)鱼类的鳔分四种类型;分析结果进一步证实鳅(鱼它)鱼类是一个单源群,作为一亚科可分为异鳔鳅(鱼它)属和鳅(鱼它)属,后者又分为原鳅(鱼它)和鳅(鱼它)二个亚属。     

根源ABA参与气孔调节的数学模拟

建立了包括植物体内的水分传输,并有根源ABA参与的气孔调节模型,模拟了饱和水气压差(VPD)、气温、表层土壤含水量(θ_(s1))等环境因子对叶片水势、木质部汁液中ABA浓度([ABA]_x)及气孔导度的影响。结果显示,VPD和气温的变化能够改变叶片水势及气孔导度;[ABA]_x几乎不受VPD和气温变化的影响,却决定着叶片水势及气孔导度对VPD和气温变化的响应幅度;θ_(s1)影响[ABA]_x,并由此影响气孔导度,但相比之下对叶片水势的作用并不显著。     

Finding the right organelle. Targeting signals in mitochondrial outer-membrane proteins

The mitochondrial outer membrane contains a diverse set of proteins that includes enzymes, components of the preprotein translocation machinery, pore-forming proteins, regulators of programmed cell death, and those that control the morphology of the organelle. All these proteins, like the vast majority of mitochondrial proteins, are encoded in the nucleus, so they are synthesized in the cytosol and contain signals that are essential for their subsequent import into mitochondria. This review summarizes our current knowledge of the signals that target mitochondrial outer-membrane proteins to their correct intracellular location. In addition, the mechanisms by which these signals are decoded by the mitochondria are discussed.     

A new type of cell in the pulmonary epithelium of the newt Triturus alpestris Laur

Summary Single cells of a new type appear scattered among pneumocytes in the pulmonary epithelium. The surfaces of these cells communicate with the air space and display numerous finger-like microvilli. In comparison to pneumocytes, these cells have a more lucid cytoplasm and their apical parts contain large amounts of electron-lucent vesicles and electron-dense granules, which are probably released into the lumen of the lung. These secretory cells exhibit a yellow formaldehyde-induced fluorescence, which suggests that they belong to the class of APUD cells.     

Looking into the water with a facet eye

The apparent velocity and apparent size of objects approaching an animal strongly depend on their size, their position within the visual field and on the path along which they move. It also makes a considerable difference whether both the animal and the objects are in air, or whether the animal looks from one medium into the other, as is the case in animals that live at the water surface. To systematically investigate this situation we calculated apparent velocity and size in the midsagittal plane of approaching objects of flat horizontal, rodlike vertical and spherical shape. We confine our investigation to object movements along straight horizontal and vertical paths and consider the situation for eyes with and without acute zones. The apparent velocity of an approaching object is low in the far field and increases rapidly close to the eye in both air and water. Along horizontal paths and close to the animal it is higher in water than in air. Along vertical paths and close to the animal it is higher in air than in water. Both relationships are exaggerated when there is an acute zone for vertical resolution along the animal's horizon. Boundary curves are calculated along which an approaching object is seen by a linearly increasing number of receptors. The change of apparent size is characterized by the density of these lines. Below the water surface the change of apparent size is similar to that of the apparent velocity. The apparent size of a horizontally elongated object approaching along a horizontal path increases steadily, that of a vertically elongated object along a vertical line initially increases, but can decrease again near the water surface. An acute zone substantially changes the shape and density of these contour lines. The biological consequences of these effects are discussed.     

The behavior of the atmosphere in long-range transport

Long-range transport of gases and aerosols depends on vertical and horizontal air shifts: studies on atmospheric transport have to be based on the meteorological conditions of the environment. The aim of this paper is to review the physical principles on which meteorological models are based, and to make an exhaustive inventory of the main models used for the prognosis and diagnosis of air masses and a list of the long-range transport models associated to them. URL addresses are provided for all of these models to allow the reader to check their usefulness. A practical application is included with reference to trajectories followed by air masses that reach the Iberian Peninsula at various altitudes, depending on the synoptic meteorological situation. Further examples describe air masses entering Europe with desert dust from Africa. This dust may eventually develop into freezing nuclei and form hailstones in summer storms.     

The functions of laryngeal air sacs in primates: a new hypothesis

A possible function of laryngeal air sacs in apes and gibbons was investigated by examining the relationships between air sac distribution, call rate, call duration and body weight in a phylogenetic context. The results suggest that lack of sacs in the smaller gibbons and in humans is a derived feature. Call parameters in primates, such as rate and duration, scaled to resting breathing rate (and therefore to body weight) only in species without air sacs, which appear to modify these relationships. Apes and larger gibbons may be able to produce fast extended call sequences without the risk of hyperventilating because they can re-breathe exhaled air from their air sacs. Humans may have lost air sacs during their evolutionary history because they are able to modify their speech breathing patterns and so reduce any tendency to hyperventilate.     

Modeling of unstable heat-mass air exchange in the lungs

A mathematical model of the unsteady-state heat and mass exchange of expired air in the bronchial tree is suggested. The model includes heat and mass exchange between air and bronchial walls, and heat exchange between blood circulation and bronchial tree. A problem has been numerically solved as a unidimensional one in the quasi-steady-state formulation. It is shown that air conditioning occurs through the whole length of a respiratory tract. During inspiration bronchial walls are cooled, that in its turn induces a decrease of air temperature and water vapour content in time. That process depends on the intensity of lung blood circulation and character of air velocity changes during inspiration.     

Carcinogenic Air Toxics Exposure and Their Cancer-Related Health Impacts in the United States

Public health protection from air pollution can be achieved more effectively by shifting from a single-pollutant approach to a multi-pollutant approach. To develop such multi-pollutant approaches, identifying which air pollutants are present most frequently is essential. This study aims to determine the frequently found carcinogenic air toxics or hazardous air pollutants (HAPs) combinations across the United States as well as to analyze the health impacts of developing cancer due to exposure to these HAPs. To identify the most commonly found carcinogenic air toxics combinations, we first identified HAPs with cancer risk greater than one in a million in more than 5% of the census tracts across the United States, based on the National-Scale Air Toxics Assessment (NATA) by the U.S. EPA for year 2005. We then calculated the frequencies of their two-component (binary), and three-component (ternary) combinations. To quantify the cancer-related health impacts, we focused on the 10 most frequently found HAPs with national average cancer risk greater than one in a million. Their cancer-related health impacts were calculated by converting lifetime cancer risk reported in NATA 2005 to years of healthy life lost or Disability-Adjusted Life Years (DALYs). We found that the most frequently found air toxics with cancer risk greater than one in a million are formaldehyde, carbon tetrachloride, acetaldehyde, and benzene. The most frequently occurring binary pairs and ternary mixtures are the various combinations of these four air toxics. Analysis of urban and rural HAPs did not reveal significant differences in the top combinations of these chemicals. The cumulative annual cancer-related health impacts of inhaling the top 10 carcinogenic air toxics included was about 1,600 DALYs in the United States or 0.6 DALYs per 100,000 people. Formaldehyde and benzene together contribute nearly 60 percent of the total cancer-related health impacts. Our study shows that although there are many carcinogenic air toxics, only a few of them affect public health significantly at the national level in the United States, based on the frequency of occurrence of air toxics mixtures and cancer-related public health impacts. Future research is needed on their joint toxicity and cumulative health impacts.     

Lethal(1) aberrant immune response mutations leading to melanotic tumor formation in Drosophila melanogaster

Using P element-mediated mutagenesis we have isolated 20 X-linked lethal mutations, representing at least 14 complementation groups, which exhibit melanotic tumor phenotypes. We present the systematic analysis of this interesting group of lethal mutations that were selected for their visible melanotic or immune response. The lethal and melanotic tumor phenotypes of each lethal(1) aberrant immune response (air) mutation are pleiotropic effects of single genetic lesions. Lethality occurs throughout the larval and early pupal periods of development and larval development is extended in some air mutants. The air mutant lethal syndromes include abnormalities associated with the brain, haematopoietic organs, gut, salivary glands, ring glands, and imaginal discs. Additional characterization of the melanotic tumor mutations Tuml and tu(1)Szts have indicated that the melanotic tumor phenotype is similar to that observed in the air mutants. These studies have led to the proposal that two distinct classes of melanotic tumor mutations exist. Class 1 includes mutants in which melanotic tumors result from "autoimmune responses" or the response of an apparently normal immune system to the presence of abnormal target tissues. The Class 2 mutants display obvious defects in the haematopoietic organs or haemocytes, manifested as overgrowth, and the resulting aberrant immune system behavior may contribute to melanotic tumor formation.     

A new fluid switching flow sorter

Conventional cell sorters produce potentially hazardous microdroplets containing dyes and radiolabeled compounds commonly used to identify and trace subpopulations of cells. Many of these substances are potential toxins, mutagens, or carcinogens constituting a risk to personal associated with the sorting device. The separation of living cells for continued study of cell growth from an "in air" sample stream includes the risk of contamination with microorganisms altering the following cultures. To avoid those risks, we have constructed a new capsular flow cytometer sorter which consists of a small chamber completely encasing the sorting mechanism. Data acquisition, analysis, and processing are accomplished by using a microcomputer-based pulse height analyser.     

A Bayesian approach to functional-based multilevel modeling of longitudinal data: applications to environmental epidemiology

Flexible multilevel models are proposed to allow for cluster-specific smooth estimation of growth curves in a mixed-effects modeling format that includes subject-specific random effects on the growth parameters. Attention is then focused on models that examine between-cluster comparisons of the effects of an ecologic covariate of interest (e.g. air pollution) on nonlinear functionals of growth curves (e.g. maximum rate of growth). A Gibbs sampling approach is used to get posterior mean estimates of nonlinear functionals along with their uncertainty estimates. A second-stage ecologic random-effects model is used to examine the association between a covariate of interest (e.g. air pollution) and the nonlinear functionals. A unified estimation procedure is presented along with its computational and theoretical details. The models are motivated by, and illustrated with, lung function and air pollution data from the Southern California Children's Health Study.     

On some species of Chonopeltis (Crustacea: Branchiura) from the rivers of the extreme South West Cape region of Africa

Two new species of Chonopeltis (Crustacea: Branchiura), parasitic on cyprinid fishes, are described from rivers in the extreme S.W. Cape region of Africa. These emphasize the remarkable nature of the fauna of these rivers, which includes several endemic fishes. Like their hosts these closely related parasites came from the north and have close affinity with a species from the Orange River system. Their probable evolutionary history is discussed. Keys to both sexes of all described species of Chonopeltis are given.     

Life in the puddle: behavioural and life-cycle adaptations in the Diptera of tropical rain pools

Puddles of rain water on the surfaces of rock exposures are a little known but very common habitat for freshwater-dwelling animals. In Africa, these are inhabited by the larvae of two taxa of fly unique to these pools. One of these includes species able to survive dry periods in situ; the other includes species that must reach adulthood and migrate to survive periods when the pool is dry. Hence, the opportunity exists for a comparative study of adaptation among these species. Since puddles are small, our principal method in the study of adaptation has been the experimental manipulation of puddles and their faunas in the wild. Using this method we were able to identify the spatial consistency of pools and their unpredictable duration during the rainy season as the main selective pressure shaping adaptation. Adaptations include diapause and adaptive adjustment of the life cycle. It is the second of these that provides the focus of our interest here.     

Functional morphology and homology in the odontocete nasal complex: Implications for sound generation

The site and physiologic mechanism(s) responsible for the generation of odontocete biosonar signals have eluded investigators for decades. To address these issues we subjected postmortem toothed whale heads to interrogation using medical imaging techniques. Most of the 40 specimens (from 19 species) were examined using X-ray computed tomography (CT) and/or magnetic resonance imaging (MR). Interpretation of scan images was aided by subsequent dissection of the specimens or, in one case, by cryosectioning. In all specimens we described a similar tissue complex and identified it as the hypothetical biosonar signal generator. This complex includes a small pair of fatty bursae embedded in a pair of connective tissue lips, a cartilaginous blade, a stout ligament, and an array of soft tissue air sacs. Comparing and contrasting the morphologic patterns of nasal structures across species representing every extant odontocete superfamily reveals probable homologous relationships, which suggests that all toothed whales may be making their biosonar signals by a similar mechanism. © 1996 Wiley-Liss, Inc.     

Modeling arthropod filiform hair motion using the penalty immersed boundary method

Crickets are able to sense their surrounding environment through about 2000 filiform hairs located on a pair of abdominal cerci. The mechanism by which the cricket is able to sense a wide range of input signals using these filiform hairs of different length and orientation is of great interest. Most of the previous filiform hair models have focused on a single, rigid hair in an idealized air field. Here, we present a model of the cercus and filiform hairs that are mechanically coupled to the surrounding air, and the model equations are based on the penalty immersed boundary method. The key difference between the penalty immersed boundary method and the traditional immersed boundary method is the addition of forces to account for density differences between the immersed solid (the filiform hairs) and the surrounding fluid (air). The model is validated by comparing the model predictions to experimental results, and then the model is used to examine the interactions between multiple hairs. With multiple hairs, there is little interaction when the hairs are separated by more than 1mm, and, as they move closer, they interact through viscous coupling, which reduces the deflection of the hairs due to the air movement. We also examine the computational scalability of the algorithm and show that the computational costs grow linearly with the number of hairs being modeled.