On the diversity of the Cladocera in the tropics

The mythical concept of an impoverished tropical cladoceran fauna is refuted. On a planetary scale, around half of the cladoceran species presently known occur exclusively in the tropics-subtropics, often with considerable restriction to particular geographical subzones. On a regional (political) scale, the situation is often unclear because of the continued fragmentary nature of studies, and because political units are not a good basis for biogeographical comparisons. At the finest level of resolution (lake-perlake comparisons), there appears to be an upper limit of c. 50 cladoceran species per individual lake. No significant difference between lakes in the temperate zone and in the tropics could be established here. Daphnia is largely absent from the tropics, but is replaced by more Sidids, Moinids, and Bosminids, such that the average cladoceran community in the limnetic zone of a tropical lake is not characterized by less species but rather by lower population densities. This, in turn, is considered a consequence of higher prevalent predation levels in the tropics.     

Assessing the Physiological State of the Fucoids from the Barents Sea Littoral by the End of the Polar Night

Methods of amperometry and potentiometric titration were used to follow dark respiration (DR) and apparent photosynthesis (AP) in the fucoids Ascophyllum nodosum (L.) Le Jol, Fucus vesiculosus L., and F. serratus L. from the Barents Sea littoral by the end of the 40-day-long polar night. The macroalgae were shown to manifest species-specific low rates of photosynthesis and respiration. However, in spite of their low photosynthetic status due to the effects of subzero temperature and prolonged low or zero illumination, the macroalgae have been able to restore DR and AP to the initial level already by the day 9; the ability to restore AP depended on the level of illumination. The study of the changes in the carbonate–bicarbonate system in the light and darkness demonstrated that the macroalgae grown in darkness, in contrast to those grown in twilight, could absorb bicarbonate in darkness; however, they lost this capacity after two-day-long illumination at an irradiance of 7 mol/(m² s). Bicarbonate uptake in darkness and the capacity to restore the systems of photosynthesis and respiration in fucoid cells are discussed in the context of algal energy metabolism under the polar night conditions.     

Tubular networks in the terminal endings of the visual receptor cells in the human,the monkey,the cat and the dog

Summary A tubular network was found in the terminal endings of the visual receptor cells in the human, the monkey (Macaca mulatta), the cat and the dog. These tubules are arranged in close groups in the vicinity of the synaptic lamellae and the invaginated dendrites. According to the form, diameter, density of the tubules and to the consistence of the network formed by them one can distinguish at these places an initial type (type I), a transitory (type II) and a vesicular one (type III). In the the type III branching, bizarre forms are frequent. The diameter of all the tubules reaches 500–600 Å, their density and walls being the same as in the synaptic vesicles.Similar networks also occur in the axons of the visual receptor cells of the monkey.

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Zusammenfassung In den Endigungen der Photorezeptorzellen von Mensch, Affe (Macaca mulatta), Katze und Hund kommen aus Tubuli bestehende Komplexe vor. Organellenartig in geschlossenen Gruppen angeordnet, liegen sie in Nähe der synaptischen Lamellen und der invaginierten Dendriten. An diesen Stellen kann man nach Form, Durchmesser, Dichte und Konsistenz der von den Tubuli gebildeten Komplexe drei Typen unterscheiden: 1. einen initialen (Typus I), 2. einen Übergangstypus (Typus II) und 3. einen vesiculären Typus (Typus III). In letzterem kommen häufig verzweigte, bizarre Formen vor. Der Durchmesser sämtlicher Tubuli erreicht 500–600 Å. Ihre Dichte und ihre Wand gleicht denen der synaptischen Vesikel.Ähnliche Komplexe fanden wir auch in den Axonen der Photorezeptorzellen vom Affen.

     

Colchicine Neurotoxicity Demonstrates the Cholinergic Projection from the Supracommissural Septum to the Habenula and the Nucleus Interpeduncularis in the Rat

Colchicine injections in the supracommissural septum of the rat caused degeneration of several neurons in the nucleus triangularis septi and the nucleus septofimbrialis. The lesions resulted in significant decreases of choline acetyltransferase in the habenula (-34%) and in the nucleus interpeduncularis (-36%), thus demonstrating the existence of a major cholinergic projection to these nuclei from the supracommissural septum. A large fall in choline acetyltransferase was also noticed in the dorsal hippocampus as a consequence of colchicine damage to the fimbria-fornix fibers crossing the injected area.     

兔主动脉前庭自律细胞与窦房结电生理特性的比较

为进一步阐明左心室流出道(主动脉前庭)自律细胞的特性,及其与窦房结细胞的异同,本实验利用常规的玻璃微电极细胞内记录技术,观察了一些离子通道阻断剂分别对离体兔窦房结起搏细胞与左心室流出道慢反应自律细胞的电生理特性的影响,重点探讨了这两种自律细胞的0期、4期去极离子流的异同。结果表明:(1)用1μmol/L维拉帕米(verapamil,VER)灌流后,窦房结及主动脉前庭自律细胞的动作电位幅值(APA)、0相最大除极速率(V_(max))、最大舒张电位(MDP)绝对值、舒张期除极速率(VDD)、自发放电频率(RPF)均明显下降,复极90％时间(APD_(90))延长(P<0.05)。(2)用180μmol/L氯化镍(NiCl_2)灌流,两自律细胞的VDD均明显下降;APA、V_(max)和RPF也显著降低,且窦房结细胞的APD_(90)明显延长。(3)给予2 mmol/L 4-氨基吡啶(4-AP)后,窦房结及主动脉前庭自律细胞的VDD均明显增快,MDP绝对值、APA和V_(max)显著下降,APD_(90)明显延长(P<0.05)。(4)给予2 mmol/L氯化铯(CsCl),两自律细胞的VDD及RPF均明显变慢。结果提示:(1)主动脉前庭自发慢反应电位的0相、4相去极离子流及复极离子流均与窦房结优势起搏细胞相似。(2)主动脉前庭起搏细胞Ca~(2+)内流为其0相主要去极离子流,复极过程主要由K~+外流引起,4相自动除极以K~+外流衰减为主,另外     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418     

Characterization of the composition of the aqueous humor and the vitreous body of the eye of the frog Rana temporaria L

This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations. To determine collagen, a spectral-fluorescent probe, cyanine dye, was used. The presence of collagen in AH of the frog was found at the first time. The total content of electron donors (ascorbic and uric acids, tryptophan, and tyrosine) in VB and HA was roughly estimated at ~ 1.5 × 10^− 4 mol/L. Both VB and AH absorb light in similar UV regions. The total protein and albumin contents in AH were found to be somewhat higher than those in VB. The uric acid content was at an equally low level in both intraocular media. It is supposed that the similarity of VB and AH compositions shown in this work is due to some exchange between VB and AH contents in the course of accommodation. The role of intraocular fluids in physiological functions of the eye and in protecting the retina against UV light is discussed.     

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl,Gallus gallus

Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices     

Movement of the tube cell in the lily style in the absence of the pollen grain and the spent pollen tube

Our model proposes that pollen tube growth is a form of cell movement where the tube tip can be considered analogous to a migrating cell which leaves a trail of extracellular matrix (the spent pollen tube) behind. We demonstrate that the tube cell can convey the sperm cells to the ovule and effect fertilization even in the absence of the pollen grain and the spent pollen tube. Adhesion is an integral part of cell attachment and movement in animal systems. We show that in vivo-grown pollen tubes grow beneath the cuticle of the stylar transmitting tract epidermis and directly adhere to one another and the outer wall of the epidermal cells. A fibrous wall material is found to cover the tip of the pollen tube cell wall and the surface of the transmitting tract cells where the two adhere. Fixation methods to preserve adhesive compounds were used. The pollen-tubes grown in vivo, but not in vitro, show star-shaped clusters of F-actin microfilaments in the region back from the tip, as seen by rhodamine-phalloidin staining. These configurations are similar to focal adhesions seen in moving animal cells.     

Ectogenesis and the case against the right to the death of the foetus

Ectogenesis, or the use of an artificial womb to allow a foetus to develop, will likely become a reality within a few decades, and could significantly affect the abortion debate. We first examine the implications for Judith Jarvis Thomson’s violinist analogy, which argues for a woman’s right to withdraw life support from the foetus and so terminate her pregnancy, even if the foetus is granted full moral status. We show that on Thomson’s reasoning, there is no right to the death of the foetus, and abortion is not permissible if ectogenesis is available, provided it is safe and inexpensive. This raises the question of whether there are persuasive reasons for the right to the death of the foetus that could be exercised in the context of ectogenesis. Eric Mathison and Jeremy Davis have examined several arguments for this right, doubting that it exists, while Joona Räsänen has recently criticized their reasoning. We respond to Räsänen’s analysis, concluding that his arguments are unsuccessful, and that there is no right to the death of the foetus in these circumstances.     

Effect of the Cerebral Tryptaminergic System on the Turnover of Dopamine in the Striatum of the Rat

The effect of the cerebral 5-hydroxytryptamine system on the turnover of striatal 3,4-dihydroxyphenyl-ethylamine (dopamine) was investigated by measuring the level of dopamine and one of its metabolites in rats depleted of cerebral 5-hydroxytryptamine or treated with a 5-hydroxytryptamine receptor blocker. Treatment with p-chlorophenylalanine induced, in addition to a reduction in striatal 5-hydroxytryptamine and 5-hydroxyindol-3-ylacetic acid, an increase in the striatal concentration of dopamine, a diminution in the concentration of homovanillic acid in the same cerebral area, and a reduction in the rise of this acid after the administration of a butyrophenone derivative or tetrabenazine. Treatment with methysergide also reduced the increase of homovanillic acid induced by the butyrophenone. When probenecid was given to rats treated with p-chlorophenylalanine, homovanillic acid failed to accumulate, whereas the accumulation of 5-hydroxyindol-3-ylacetic acid was unaffected. The decay of dopamine after alpha-methyl-p-tyrosine administration was normal for the first 6 h but was later reduced in rats given p-chlorophenylalanine or methysergide. The results suggest that the lack of activation of 5-hydroxytryptamine receptors leads to a reduction in the turnover of dopamine in the nigrostriatal pathway.     

Changes in the size of the nucleoli of the Purkinje cells in the canine cerebellum in the postresuscitation period

The changes in the size of Purkinje cell (PC) nucleolus in the lateral and medial cerebellum zones were studied in dogs with different degree of neurologic status recovery after clinical death of various etiology and duration. PC always possess one nucleolus in the control and experimental groups. In the case of complete neurologic status recovery of animals the area of PC nucleolus increases in both zones studied, irrespective of the cause of clinical death. In the case of neurologic disorders the increase in PC nucleolus area is clearly expressed only in the medial zone of the cerebellum, being insignificant in the lateral zone. It is suggested that adaptive characteristics of PC are distinct in the two compared zones, which leads to greater PC vulnerability in the lateral zone during deep hypoxia.     

Crystallographic structure of the retinal and the protein after deprotonation of the Schiff base: the switch in the bacteriorhodopsin photocycle

We illuminated bacteriorhodopsin crystals at 210K to produce, in a photostationary state with 60% occupancy, the earliest M intermediate (M1) of the photocycle. The crystal structure of this state was then determined from X-ray diffraction to 1.43 A resolution. When the refined model is placed after the recently determined structure for the K intermediate but before the reported structures for two later M states, a sequence of structural changes becomes evident in which movements of protein atoms and bound water are coordinated with relaxation of the initially strained photoisomerized 13-cis,15-anti retinal. In the K state only retinal atoms are displaced, but in M1 water 402 moves also, nearly 1A away from the unprotonated retinal Schiff base nitrogen. This breaks the hydrogen bond that bridges them, and initiates rearrangements of the hydrogen-bonded network of the extracellular region that develop more fully in the intermediates that follow. In the M1 to M2 transition, relaxation of the C14-C15 and C15=NZ torsion angles to near 180 degrees reorients the retinylidene nitrogen atom from the extracellular to the cytoplasmic direction, water 402 becomes undetectable, and the side-chain of Arg82 is displaced strongly toward Glu194 and Glu204. Finally, in the M2 to M2' transition, correlated with release of a proton to the extracellular surface, the retinal assumes a virtually fully relaxed bent shape, and the 13-methyl group thrusts against the indole ring of Trp182 which tilts in the cytoplasmic direction. Comparison of the structures of M1 and M2 reveals the principal switch in the photocycle: the change of the angle of the C15=NZ-CE plane breaks the connection of the unprotonated Schiff base to the extracellular side and establishes its connection to the cytoplasmic side.     

Trans-Kemalism: the politics of the Turkish state in the diaspora

Abstract

In contrast to the huge amount of research on Turkish migration and migrants, the diasporic politics of the Turkish Kemalist state constitutes a neglected research subject in the scholarship on Turkish diaspora. How does the Turkish state reach out to its nationals and expatriates abroad? In what ways does the Turkish Republic seek to make Islam (as it does in Turkey) into an instrument legitimizing its politicizing and mobilizing enterprises? To explore these questions, this article investigates the long-distance Kemalism engaged in by the Turkish state to Turkify and secularize its nationals in the diaspora, using its activities in Australia as its case study. In sketching out trans-Kemalism's dimensions, the analysis directs attention to the intimate relationship between the political and religious fields of transnationalism manufactured by the state. The paper concludes that the intense political polarization in Turkey in the present makes the future of trans-Kemalism abroad somewhat uncertain.     

初生与成年牦牛心肌的组织学结构比较

为探究牦牛心肌发育过程中组织学结构的变化,采用组织学、组织化学和免疫组织化学方法对初生和成年牦牛心肌的组织学结构、心钠素（ANP）和缝隙连接蛋白43（Cx43）的表达情况进行了观察。结果显示,初生牦牛心肌细胞数量少且细短,闰盘为直线型或V型,心肌细胞间以Ⅲ型胶原纤维为主,Ⅰ型胶原纤维较少;成年牦牛心肌细胞粗长,其数量是初生牦牛的2倍,闰盘呈竹节样吻合或阶梯状,心肌细胞间以Ⅰ型胶原纤维为主。初生和成年牦牛,ANP在心房肌细胞中均表达强烈,且右心房表达量显著高于左心房,心室肌细胞中不表达。ANP在普肯耶纤维中有少量表达。初生牦牛心房肌细胞ANP表达量高于成年牦牛。在心肌细胞膜和胞质内,初生牦牛Cx43表达强于成年牦牛,但在闰盘内,成年牦牛Cx43表达强于初生牦牛。Cx43在初生和成年牦牛的普肯耶纤维中均呈膜阳性。结果提示,初生与成年牦牛相比,成年牦牛的心肌细胞变粗长且数量增多,ANP在心房肌表达减弱,Cx43在闰盘表达更显著,说明成年牦牛较初生牦牛适应循环变化的代偿能力呈进行性减弱;细胞间牢固性增加,有助于实现心肌收缩信号的迅速传导。     

Cytophotometric analysis of the cell population composition of the the preoptic area of the hypothalamus in the common frog

DNA contents in squashed cells of the adult frog hypothalamic preoptic region (HPR) were measured using the Feulgen and UV cytophotometry techniques. The histone-DNA ratio in the cell nucleus was determined by means of a combined Feulgen-heparin-Alcian blue staining procedure. The nuclei of the vast majority of HPR cells have a diploid DNA content. However, in cells of this group the mean values of DNA amount and the distribution range were always higher than those in hepatocytes used as a diploid standard. Such a heterogeneity in DNA content in the diploid part of HPR cell population could apparently suggest some differences in the nuclear chromatin arrangement to be always higher in spring before the frog spawning, and it seems to be characteristic of this type of cells. About 1 per cent of cells with hyperdiploid surplus of DNA (H2c cells) as well as of tetraploid cells (4c and 2c X 2 cells) is found in HPR in frogs sacrificed both in winter and in summer. The quota of these cells has no reference either to the frog's age or to the annual cycle. The fact that the mean DNA values in H2c and 4c cells are much higher than in the standard cannot be explained by the presence of different amounts of nuclear proteins only. It is suggested that at least some part of the highest DNA values may be due to an actual extra DNA synthesis in a small constantly existing pool of HPR cell population.     

Making the past serve the present

Botany has been successfully introduced to environmental design students, as a foundation for ecology and horticulture, in the form of extracts from an 18th century text which students are asked to criticise and update. This historical introduction demonstrates something of both the development ofthe subject and the students ' range of knowledge in it; and is a useful prompt for study. It encourages precision in the use of words, and emphasizes the provisional nature of scientific explanations. Suggestions for the use of this approach in other subjects and more advanced studies are made.     

Herbal bioactivation: the good, the bad and the ugly

It has been well established that the formation of reactive metabolites of drugs is associated with drug toxicity. Similarly, there are accumulating data suggesting the role of the formation of reactive metabolites/intermediates through bioactivation in herbal toxicity and carcinogenicity. It has been hypothesized that the resultant reactive metabolites following herbal bioactivation covalently bind to cellular proteins and DNA, leading to toxicity via multiple mechanisms such as direct cytotoxicity, oncogene activation, and hypersensitivity reactions. This is exemplified by aristolochic acids present in Aristolochia spp, undergoing reduction of the nitro group by hepatic cytochrome P450 (CYP1A1/2) or peroxidases in extrahepatic tissues to reactive cyclic nitrenium ion. The latter was capable of reacting with DNA and proteins, resulting in activation of H-ras oncogene, gene mutation and finally carcinogenesis. Other examples are pulegone present in essential oils from many mint species; and teucrin A, a diterpenoid found in germander (Teuchrium chamaedrys) used as an adjuvant to slimming diets. Extensive pulegone metabolism generated p-cresol that was a glutathione depletory, and the furan ring of the diterpenoids in germander was oxidized by CYP3A4 to reactive epoxide which reacts with proteins such as CYP3A and epoxide hydrolase. On the other hand, some herbal/dietary constituents were shown to form reactive intermediates capable of irreversibly inhibiting various CYPs. The resultant metabolites lead to CYP inactivation by chemical modification of the heme, the apoprotein, or both as a result of covalent binding of modified heme to the apoprotein. Some examples include bergamottin, a furanocoumarin of grapefruit juice; capsaicin from chili peppers; glabridin, an isoflavan from licorice root; isothiocyanates found in all cruciferous vegetables; oleuropein rich in olive oil; dially sulfone found in garlic; and resveratrol, a constituent of red wine. CYPs have been known to metabolize more than 95% therapeutic drugs and activate a number of procarcinogens as well. Therefore, mechanism-based inhibition of CYPs may provide an explanation for some reported herb-drug interactions and chemopreventive activity of herbs. Due to the wide use and easy availability of herbal medicines, there is increasing concern about herbal toxicity. The safety and quality of herbal medicine should be ensured through greater research, pharmacovigilance, greater regulatory control and better communication between patients and health professionals.     

From the biology of the individual to the dynamics of the population: bridging the gap in fish early life studies

The mean properties of larval fish populations do not necessarily reflect the properties of the mean individual. For example, the change in mean length in a population with time may not reflect the average individual growth rate, since individual growth rates and survival probability are linked so that slow growing individuals suffer higher mortality. Hence, mean growth rate indicated from population data could be biased upwards. Factors which influence the magnitude and variability of individual growth rates can exert nonlinear effects on population survival. Two categories of process must be considered: first, the variability in exposure of the average individual as a consequence of individual variability in dispersal through a patchy environment; and second, the intrinsic variability between individuals expressed even under equal exposure conditions. These two aspects have been addressed independently, the first by lagrangian modelling of individual fish larvae linked to spatially resolved hydrodynamic models, and the second by strategic biological modelling. In this paper, progress towards the goal of individually based larval fish ecosystem models is reviewed, highlighting the space and time scales which may be important in such systems, and identifying the gaps in current knowledge of larval biology.     

On the identity of the thyrotropic cell in the red-spotted newt

Summary Although the pars distalis of the red-spotted newt has previously undergone extensive cytological examination, the identity of its thyrotropic cells has remained uncertain. From the present ultrastructural study, cells of type 3 (Masur, 1969) containing granules 150–180 nm in diameter are concluded to be the thyrotropes. Such cells were found to be present in the regions of the pars distalis where thyroidectomy cells arise after ablation of the thyroid gland. Cells of type 3 are probably identical with a population of cells containing granules which stain with silver methenamine indicating the presence of a glycoprotein such as thyroid stimulating hormone (TSH). Thyroidectomy cells containing a few residual granules 150–180 nm in diameter were occasionally found in partes distales from newts killed 3 or 7 days after ablation of the thyroid gland, and were abundant in pituitaries 21 days after thyroidectomy. Only cells of type 3 responded (by vacuolation of granules) when animals were immersed in water containing 10 g/l of thyroxine. No cells of the pars distalis showed cytological change after administration of synthetic thyrotropic releasing hormone (TRH) giving additional support to the view that this hormone has no stimulatory role in amphibians.Work supported in part by research grant 1 R01 AM 16731-01 from the Institute of Arthritis, Metabolism and Metabolic Diseases and in part by grant PCM 75-17637 from the National Science Foundation