Asymmetry of cilia and of mice and men.

Evidence is given for the opinion that cilia in the early embryo, by their work, determine the laterality of the body; without ciliary work body laterality would be randomized. More exactly, monocilia in the primitive node are responsible for this determination. They have been described as being of the 9+0 type, but with dynein arms and with a gyrating movement. The orientation of the monocilia on the epithelium is of no importance but the direction of their gyration is, as may also be the shape of the node. The chirality of the cilia is thus reflected directly in the asymmetry of the body. The dynein arms go clockwise as seen from the base to tip and the ciliary rotation is in the same direction. The resulting waterflow is towards the left and so is the movement of the forming heart. In most subgroups of the immotile-cilia syndrome this mechanism does not work and equally many individuals will be born with situs inversus as with situs solitus. An exception is the immotile-cilia subgroup, named 'microtubule transposition', which is characterized by all cilia having a 9+0 structure throughout most of their length.     

Molecular characterisation of species and genotypes of Cryptosporidium and Giardia and assessment of zoonotic transmission

The molecular characterisation of species and genotypes of Cryptosporidium and Giardia is essential for accurately identifying organisms and assessing zoonotic transmission. Results of recent molecular epidemiological studies strongly suggest that zoonotic transmission plays an important role in cryptosporidiosis epidemiology. In such cases the most prevalent zoonotic species is Cryptosporidium parvum. Genotyping and subtyping data suggest that zoonotic transmission is not as prevalent in the epidemiology of giardiasis. Molecular characterisation of Cryptosporidium and Giardia is a relatively recent application that is evolving as new genes are found that increase the accuracy of identification while discovering a greater diversity of species and yet unnamed taxa within these two important genera. As molecular data accumulate, our understanding of the role of zoonotic transmission in epidemiology and clinical manifestations is becoming clearer.     

The septomaxilla of fossil and recent synapsids and the problem of the septomaxilla of monotremes and armadillos

The septomaxilla is a paired intramembranous ossification in the external nares that occurs in Lepidosauria among Recent Sauropsida and is purported to be present in Monotremata and Dasypodidae (armadillos) among Recent Mammalia. A review of neontological and palaeontological evidence regarding this element in mammals supports the following conclusions: (1) monotremes have a true septomaxilla resembling that known for non-mammalian therapsids and some Mesozoic mammals; (2) the element in dasypodids is a neomorph; it neither resembles the septomaxilla of other synapsids nor does it exhibit the same relationship to the developing nasal-floor cartilage as the septomaxilla of lepidosaurs and monotremes; (3) a septomaxilla is lacking in all Recent therians, and there is no evidence that this bone is fused to the premaxilla in Recent therians, as has been suggested by previous authors.     

The septomaxilla of fossil and recent synapsids and the problem of the septomaxilla of monotremes and armadillos

The septomaxilla is a paired intramembranous ossification in the external nares that occurs in Lepidosauria among Recent Sauropsida and is purported to be present in Monotremata and Dasypodidae (armadillos) among Recent Mammalia. A review of neontological and palaeontological evidence regarding this element in mammals supports the following conclusions: (1) monotremes have a true septomaxilla resembling that known for non-mammalian therapsids and some Mesozoic mammals; (2) the element in dasypodids is a neomorph; it neither resembles the septomaxilla of other synapsids nor does it exhibit the same relationship to the developing nasal-floor cartilage as the septomaxilla of lepidosaurs and monotremes; (3) a septomaxilla is lacking in all Recent therians, and there is no evidence that this bone is fused to the premaxilla in Recent therians, as has been suggested by previous authors.     

地衣二元性及其概念的双重理解与思考

本文简短回顾人类对地衣的认识过程之后,认为从地衣二元性（地衣的菌藻共生联合）和从地衣一元性（地衣的真菌本质）不同角度理解地衣都是正确的,被你之为“地衣概念的双重理解”。但作为地衣的定义似乎只能主要从地衣的二元性概念去表达,并分析其原因。对现在使用的地衣定义提出了某些看法与修改意见。     

Mechanisms and function of flower and inflorescence reversion

Flower and inflorescence reversion involve a switch from floral development back to vegetative development, thus rendering flowering a phase in an ongoing growth pattern rather than a terminal act of the meristem. Although it can be considered an unusual event, reversion raises questions about the nature and function of flowering. It is linked to environmental conditions and is most often a response to conditions opposite to those that induce flowering. Research on molecular genetic mechanisms underlying plant development over the last 15 years has pinpointed some of the key genes involved in the transition to flowering and flower development. Such investigations have also uncovered mutations which reduce floral maintenance or alter the balance between vegetative and floral features of the plant. How this information contributes to an understanding of floral reversion is assessed here. One issue that arises is whether floral commitment (defined as the ability to continue flowering when inductive conditions no longer exist) is a developmental switch affecting the whole plant or is a mechanism which assigns autonomy to individual meristems. A related question is whether floral or vegetative development is the underlying default pathway of the plant. This review begins by considering how studies of flowering in Arabidopsis thaliana have aided understanding of mechanisms of floral maintenance. Arabidopsis has not been found to revert to leaf production in any of the conditions or genetic backgrounds analysed to date. A clear-cut reversion to leaf production has, however, been described in Impatiens balsamina. It is proposed that a single gene controls whether Impatiens reverts or can maintain flowering when inductive conditions are removed, and it is inferred that this gene functions to control the synthesis or transport of a leaf-generated signal. But it is also argued that the susceptibility of Impatiens to reversion is a consequence of the meristem-based mechanisms controlling development of the flower in this species. Thus, in Impatiens, a leaf-derived signal is critical for completion of flowering and can be considered to be the basis of a plant-wide floral commitment that is achieved without accompanying meristem autonomy. The evidence, derived from in vitro and other studies, that similar mechanisms operate in other species is assessed. It is concluded that most species (including Arabidopsis) are less prone to reversion because signals from the leaf are less ephemeral, and the pathways driving flower development have a high level of redundancy that generates meristem autonomy even when leaf-derived signals are weak. This gives stability to the flowering process, even where its initiation is dependent on environmental cues. On this interpretation, Impatiens reversion appears as an anomaly resulting from an unusual combination of leaf signalling and meristem regulation. Nevertheless, it is shown that the ability to revert can serve a function in the life history strategy (perenniality) or reproductive habit (pseudovivipary) of many plants. In these instances reversion has been assimilated into regular plant development and plays a crucial role there.     

Studies of the birefringence and birefringence dispersion of polypeptides and proteins

An apparatus has been constructed which permits the polarimetric observation of streaming solutions of macromolecules. The apparatus is a streaming birefringence device allowing the usual measurements of birefringence parallel to the cylinder axis but which in addition transmits light in the radial direction. Installation of the apparatus between the polarizer and analyzer of a Rudolph polarimeter makes possible the measurement of changes in optical rotation, dichroism and birefringence. The present work is concerned with the latter effect. The systems studied were α-helical polyglutamic acid, paramyosin, and collagen (ichthyocol). The combined measurements of radial and axial birefringence completely determines the refractive index ellipsoid of the streaming fluid. This result in turn permits the testing of the Peterlin-Stuart distribution function for streaming in a Couette device, apart from a proportionality constant. The comparison between theory and experiment is very satisfactory provided the system is reasonably homogeneous with regard to molecular length and is sufficiently dilute. On the other hand, it is concluded that the Peterlin-Stuart optical factor seriously overestimates the “form” birefringence in agreement with recent results and conclusions of Taylor and co-workers. The apparatus permits the study of the dispersion of the birefringence in the radial direction. The dispersion of collagen follows a one-term Sellmeier formula and is dominated by absorption bands in the neighborhood of 2000 A. On the other hand, the dispersion of the α-helical systems is complex and requires a multiterm Sellmeier formula. This contrast between the two kinds of polypeptidc helices is similar to results obtained with other optical techniques and is attributed to the splitting of absorption bands in the α-helix.     

Correlation between family and age of manifestation of lung and colon cancer

The probability to develop lung cancer before 80 years of age is 1.67 and 0.18% for the male and female populations of Kharkov, respectively; the probability to develop large-intestine cancer is 0.92 and 0.49%, respectively. The correlation coefficient (r) of the age of manifestation (AM) of cancer in parent-offspring pairs is 0.47. These correlation coefficients for the father-son, mother-daughter, mother-son, and father-daughter pairs are 0.64, 0.49, 0.44, and 0.37, respectively. If the parent has lung cancer, the correlation is stronger (r = 0.71). On average, cancer is manifested in offspring earlier than in parents (57 and 63 years, respectively); the differences in the father-daughter and mother-son pairs are 8.2 and 2.8 years, respectively. The best prognostic parameter is the AM of cancer in the father with respect to the AM in the son (byx = 0.45).     

Heat capacity and thermodynamic characteristics of denaturation and glass transition of hydrated and anhydrous proteins

Calorimetric measurements of absolute heat capacity have been performed for hydrated (11)S-globulin (0 < C(H(2)O) < 25%) and for lysozyme in a concentrated solution, both in the native and denatured states. The denaturation process is observed in hydrated and completely anhydrous proteins; it is accompanied by the appearance of heat capacity increment (Delta(N)(D)C(p)), as is the case for protein solutions. It has been shown that, depending on the temperature and water content, the hydrated denatured proteins can be in a highly elastic or glassy states. Glass transition is also observed in hydrated native proteins. It is found that the denaturation increment Delta(N)(D)C(p) in native protein, like the increment DeltaC(p) in denatured protein in glass transition at low water contents, is due to additional degrees of freedom of thermal motion in the protein globule. In contrast to the conventional notion, comparison of absolute C(p) values for hydrated denatured proteins with the C(p) values for denatured proteins in solution has indicated a dominant contribution of the globule thermal motion to the denaturation increment of protein heat capacity in solutions. The concentration dependence of denaturing heat absorption (temperature at its maximum, T(D), and thermal effect, DeltaQ(D)) and that of glass transition temperature, T(g), for (11)S-globulin have been studied in a wide range of water contents. General polymeric and specific protein features of these dependencies are discussed.     

Ontogeny and phylogeny of endothermy and torpor in mammals and birds

Endothermic thermoregulation in small, altricial mammals and birds develops at about one third to half of adult size. The small size and consequently high heat loss in these young should result in more pronounced energetic challenges than in adults. Thus, employing torpor (a controlled reduction of metabolic rate and body temperature) during development would allow them to save energy. Although torpor during development in endotherms is likely to occur in many species, it has been documented in only a few. In small, altricial birds (4 orders) and marsupials (1 order), which are poikilothermic at hatching/birth, the development of competent endothermic thermoregulation during cold exposure appears to be concurrent with the capability to display torpor (i.e. poikilothermy is followed by heterothermy), supporting the view that torpor is phylogenetically old and likely plesiomorphic. In contrast, in small, altricial placental mammals (2 orders), poikilothermy at birth is followed first by a homeothermic phase after endothermic thermoregulation is established; the ability to employ torpor develops later (i.e. poikilothermy-homeothermy-heterothermy). This suggests that in placentals torpor is a derived trait that evolved secondarily after a homeothermic phase in certain taxa perhaps as a response to energetic challenges. As mammals and birds arose from different reptilian lineages, endothermy likely evolved separately in the two classes, and given that the developmental sequence of torpor differs between marsupials and placentals, torpor seems to have evolved at least thrice.     

Endocytosis and sorting of ErbB2 and the site of action of cancer therapeutics trastuzumab and geldanamycin

ErbB2 is a transmembrane tyrosine kinase whose surface overexpression is linked to tumorigenesis and poor prognosis in breast cancer patients. Two models have emerged that account for the high surface distribution of ErbB2. In one model, the surface pool is dynamic and governed by a balance between endocytosis and recycling, whereas in the other it is retained, static, and excluded from endocytosis. These models have contrasting implications for how ErbB2 exerts its biological function and how cancer therapies might down-regulate surface ErbB2, such as the antibody trastuzumab (Herceptin) or the Hsp90 inhibitor geldanamycin. Little is known, however, about how these treatments affect ErbB2 endocytic trafficking. To investigate this issue, we examined breast carcinoma cells by immunofluorescence and quantitative immunoelectron microscopy and developed imaging and trafficking kinetics assays using cell surface fluorescence quenching. Surprisingly, trastuzumab does not influence ErbB2 distribution but instead recycles passively with internalized ErbB2. By contrast, geldanamycin down-regulates surface ErbB2 through improved degradative sorting in endosomes exclusively rather than through increased endocytosis. These results reveal substantial dynamism in the surface ErbB2 pool and clearly demonstrate the significance of endosomal sorting in the maintenance of ErbB2 surface distribution, a critical feature of its biological function.     

Modeling and measurements of solid-liquid and vapor-liquid equilibria of polyols and carbohydrates in aqueous solution

The solubilities of five saccharides in water have been measured at various temperatures. This includes the monosaccharides xylose and galactose, and the disaccharides maltose monohydrate, cellobiose and trehalose dihydrate. A method that uses interaction energies and interaction parameters calculated with molecular mechanics methods has shown to give good predictions of the phase behavior of a variety of mixtures, including glycols and small saccharides in aqueous solution. The method is completely predictive, as the strength of the molecular interactions is determined with a theoretical method in the absence of any phase equilibrium data. For calculating solubilities, experimental values for the melting points and the heats of fusion of the compounds under study are, however, necessary. The solubilities of the five saccharides listed above, raffinose and meso-erythritol in water were calculated with this method. The calculated solubilities are in reasonably good agreement with experiment, and in the case of meso-erythritol, which is a polyalcohol (polyol), and galactose, the agreement between prediction and experiment is excellent. Also the vapor pressures of water over several polyols and saccharides in aqueous solution have been predicted with this method, giving results in excellent agreement with the experimental values.     

硼、镉元素及其交互作用与油菜产量和品质

硼和镉两种元素是影响油菜产量和品质的两个重要因素.硼是植物生长所必需的微量元素,施硼是油菜种植的必需环节;镉是植物生长的非必要元素,易在油菜体内富集,可能通过食物链危害人体健康.本文主要从镉含量与油菜食品安全品质角度考虑,阐述了油菜对镉的积累和耐受机制;同时,概括了前人总结的硼对油菜的产量和品质的影响.最后,结合本人研究区广西地区土壤有效硼含量低,全镉含量高的现状,提出运用硼镉交互作用机理,通过施加适量硼肥,提高油菜的产量和品质,消除土壤镉的潜在危害,从本质上改善该地区土壤存在的低硼高镉现状.     

Analytical and folk concepts of race and ethnicity

Prejudice is found in all societies, but it is a particular problem in immigrant societies. In this article we use Bogardus's social‐distance scale to identify patterns of ethnic prejudice in Australia and test four explanations to account for it: personality, socio‐psychology, social structure, and social contact. The data are a national sample of the Australian‐born and of three immigrant groups: Maltese, Lebanese, and Vietnamese. The results show that ethnic prejudice is not unidimensional and that there are at least two dimensions, which we label social prejudice and cultural prejudice. The analyses indicate that Australians and longer‐resident Maltese emphasize the social dimension of prejudice; the newly arrived Vietnamese emphasize the cultural dimension. For Australians, prejudice is rooted in personality factors; but for immigrants, none of the four explanations is significant. The results point to the interaction between personality factors and social learning within the society as the most important determinant of ethnic prejudice.     

Methylation of DNA of the brain and liver of young and old rats.

In vitro methylation of purified DNA and chromatin-DNA in nuclei of the liver and brain of young (18 week) and old (120 week) female rats has been studied using 3H-SAM as the -CH3 group donor. Incorporation of -CH3 group is higher in old liver and brain, but it is far higher in the latter. 5 mC is 11% lower in the old brain, but there is no difference in the liver. Methylation by Hpa II methylase does not show any difference in the incorporation of -CH3 group into DNA of the liver of the two ages. However, its incorporation is lower in the old brain. Methylation by Msp I methylase causes slightly higher incorporation of -CH3 groups in the old brain. This shows a higher percentage of unmethylated external cytosines in the 5'-CCGG-3' sequences. On the contrary, methylation by Eco RI methylase is considerably higher in the old brain. These studies show alterations in the methylation status of the DNA during ageing which may cause changes in the expression of genes.     

Importance and detection of virus reservoirs and compartments of HIV infection

Current therapies for treating HIV-1 infection are capable of suppressing virus load in blood to undetectable levels, and result in marked clinical improvement. Despite this suppression, HIV-1 infection persists and virus load quickly rebounds when therapy is interrupted. The origin of the rebounding virus is unknown, but is thought to result from continuing viral replication in anatomic or cellular compartments, and the release of virus from latent infection in reservoirs.     

黄花补血草的开发利用价值与栽培技术

黄花补血草是蓝雪科补血草属多年生草本植物,在我国华北、西北及四川等省均有分布。由于其独特的生物学特征,具有很高的开发利用价值。就黄花补血草的形态特征、分布范围、开发利用价值和其栽培技术等进行了论述。目前,必须重视黄花补血草种质资源的保护,在黄花补血草产业化种植还没有形成之前,对其利用必须走开发与保护相结合的道路。     

Capacity of cytochrome and alternative path in coupled and uncoupled root respiration of Pisum and Plantago

A critical duration of darkness must be exceeded for the photoperiodic induction of flowering in short-day plants. This requires detection of the light/dark transition at dusk and the coupling of this information to a time-measuring system.
Lowering the P_fr/P_tot, ratio photochemically at the end of the day did not accelerate the onset of dark timing in Pharbitis nil Choisy cv. Violet. Time-measurement was initiated when, with no change in spectral quality, the irradiance fell below a threshold value. Thus, if the light/dark transition at dusk is sensed by a reduction in P_fr, this reduction can be achieved as rapidly through thermal reactions as through photochemical ones. When given at hourly intervals during a 6-h extension of a 24-h main light period in white light, pulses of red light were as effective as continuous red light in delaying the onset of timing; pulses every 2 or 3 h were less effective. The effectiveness of intermittent red light indicates that phytochrome is the photoreceptor and the requirement for frequent exposures suggests that P_fr is lost rapidly in the dark. However, the red light pulses could not be reversed by far-red light, which argues against this hypothesis. An alternative explanation is that the perception of light as being continuous occurs only when "new" P_fr is regenerated sufficiently frequently.
The nature of the coupling of the dusk signal to the time-measuring system is discussed and it is suggested that the effect of each red light pulse is to delay the phase of the photoperiodic rhythm by 1–3 h.