Action Spectra for Step-Up Photophobic Response in Blepharisma

ABSTRACT The cells of Blepharisma which possess red pigment (blepharismin) show step-up photophobic response (temporal ciliary reversal induced by a sudden increase in light intensity). Bleaching of the cells by cold shock raised a threshold light intensity for the response, Oxidation of red pigment that produced blue pigment did not raise the threshold for the response. The action spectrum for the step-up photophobic response of the cells which possess normal red pigment had peaks at about 580, 540 and 490 nm, a value which coincided with peaks of an absorption spectrum of the red pigment. The absorption spectrum of oxidized pigment (blue pigment) shifted 20 nm toward infrared light. The action spectrum for the response of the cells which possess blue pigment also shifted 20 nm toward infrared light. Results suggest that red pigment might be involved in the step-up photophobic response. Key words. Blepharismin, ciliary reversal, photoreceptors, photoresponse.     

Identification of possible phosducins in the ciliate Blepharisma japonicum

Examination of ciliate Blepharisma japonicum whole cell lysates with an antibody against phosphoserine and in vivo labeling of cells with radioactive phosphate revealed that the photophobic response in the ciliate is accompanied by a rapid dephosphorylation of a 28 kDa protein and an enhanced phosphorylation of a 46 kDa protein. Analysis with antibodies raised against rat phosducin or human phosducin-like proteins, identified one major protein of a molecular weight of 28 kDa, and two protein bands of 40 kDa and 93 kDa. While the identified ciliate phosducin is phosphorylated in a light-dependent manner, both phosducin-like proteins exhibit no detectable dependence of phosphorylation upon illumination. An immunoprecipitation assay also showed that the ciliate phosducin is indeed phosphorylated on a serine residue and exists in a phosphorylated form in darkness and that its dephosphorylation occurs in light. Immunocytochemical experiments showed that protozoan phosducin and phosducin-like proteins are localized almost uniformly within the cytoplasm of cells adapted to darkness. Cell exposure to light caused a pronounced displacement of the cell phosducin to the vicinity of the plasma membrane; however, no translocation of phosducin-like proteins was observed upon cell illumination. The obtained results are the first demonstration of the presence and morphological localization of a possible phosducin and phosducin-like proteins in ciliate protists. Phosducin and phosducin-like proteins were found to bind and sequester the betagamma-subunits of G-proteins with implications for regulation of G-protein-mediated signaling pathways in various eukaryotic cells. The findings presented in this study suggest that the identified phosphoproteins in photosensitive Blepharisma japonicum may also participate in the regulation of the efficiency of sensory transduction, resulting in the motile photophobic response in this cell.     

OBATOCLAX and ABT-737 Induce ER Stress Responses in Human Melanoma Cells that Limit Induction of Apoptosis

Anti-apoptotic Bcl-2 family proteins, in particular, Mcl-1, are known to play a critical role in resistance of human melanoma cells to induction of apoptosis by endoplasmic reticulum stress and other agents. The present study examined whether the BH3 mimetics, Obatoclax and ABT-737, which inhibit multiple anti-apoptotic Bcl-2 family proteins, would overcome resistance to apoptosis. We report that both agents induced a strong unfolded protein response (UPR) and that RNAi knockdown of UPR signalling proteins ATF6, IRE1α and XBP-1 inhibited Mcl-1 upregulation and increased sensitivity to the agents. These results demonstrate that inhibition of anti-apoptotic Bcl-2 proteins by Obatoclax and ABT-737 appears to elicit a protective feedback response in melanoma cells, by upregulation of Mcl-1 via induction of the UPR. We also report that Obatoclax, but not ABT-737, strongly induces autophagy, which appears to play a role in determining melanoma sensitivity to the agents.     

Localization of Possible Calcium-Binding Sites in the Cilia of Paramecium caudatum

SYNOPSIS. Electron-dense deposits indicating possible Ca-binding sites were found at the ciliary base of Paramecium caudatum fixed in a glutaraldehyde solution containing 5 mM CaCl₂. The deposits appeared mainly at the inner surface of the ciliary membrane above the "ciliary necklace" region, although they could also occur in the space between the outer and the central microtubules. In some cases a ring of exactly 9 deposits was found in a ciliary cross section of a cilium.     

Effects of Organic Solvents on the Coupling Between ATP Hydrolysis and Sliding of Microtubules in Axonemes from Chlamydomonas Flagella

ABSTRACT. The effects of organic solvents on the ATPase activity and the sliding disintegration of axonemes from Chlamydomonas were investigated. The axonemal ATPase was markedly activated by methanol accompanying with marked inhibition of the sliding disintegration of axonemes. On the contrary, glycerol inhibited the ATPase activity without serious inhibition of the sliding disintegration. As far as the axonemes are not irreversibly denatured by extremely high concentration of solvents, the effects of solvents both on the ATPase and the ability of sliding are reversible. Therefore, the inhibition of sliding accompanied by the activation of ATPase is probably due to an inability to couple the hydrolysis of ATP to sliding between dynein and microtubule in the presence of methanol. The axonemal ATPase was less sensitive to vanadate inhibition after exposure to methanol. This indicates that methanol makes the dyneinADP.Pi complex unstable and increases product release. On the other hand, glycerol and ethylene glycol seem to stabilize the force generation responsible for the sliding through stabilizing the dynein.ADP.Pi complex.     

Dominance hierarchy and social grooming in female lion- tailed macaques (Macaca silenus) in the Western Ghats, India

This article reports the structure of dominance and its relationship with social grooming in wild lion-tailed macaque females. The strength of dominance hierarchy was 0.79 on a scale of 0 to 1 indicating a moderate linearity in the ranking system. Dominance scores were converted into an ordinal as well as an interval scale. Grooming scores were also converted into interval scales using standard scores. Grooming received and grooming given correlated positively and negatively respectively with dominance ranks indicating that high ranking females received more and gave less grooming. Grooming was also positively related to encounter rates for dyads of females. More grooming among adjacent ranks, and grooming being more reciprocal, occurred only in the case of dominant females. The grooming patterns, therefore, appeared to be more of despotic than egalitarian nature. While ranking macaques into different Grades of social systems ranging from despotic to egalitarian, Thierry (2004) has placed lion-tailed macaques in Grade 3 corresponding to the ‘relaxed’ social system. Our results indicate that the grooming and dominance relationships in this species are more despotic, and hence, the Grade for this species requires to be shifted toward 2 or 1.     

Target-derived molecules that influence the development of neurons in the avian ciliary ganglion

The developing avian ciliary ganglion has been a particularly amenable system for the identification, isolation, and characterization of putative target-derived molecules that mediate retrograde interaction. To date a number of biochemically distinct activities that regulate neuronal survival, transmitter phenotype, and chemosensitivity of ciliary ganglion neruons have been identified. Of these, only two survival-promoting molecules have been purified to homogeneity: ciliary neurotrophic factor and a related molecule, growth-promoting activity. A somatostatin-inducing activity found in cultured choroid cells is very likely to be chick activin A. Other molecules that regulate acetylcholine and acetylcholine receptor expression comigrate on a gel filtration column at a molecular weight of 50–60 kD, but they have yet to be isolated. Once molecules that mimic retrorgrade influences are identified, a number of criteria must be met before their physiological significance can be established. These criteria are (1) availability of the molecule from the target at the appropriate time in development: (2) ability of the neurons to respond to the molecule at the appropriate time in development: (3) demonstration that blocking the activity or availability of the molecule is able to block the target-derived developmental change expressed in the neurons. Of the molecules that are thought to retrogradely influence ciliary neuron development, only growth-promoting activity is known to meet criteria 1 and 2, and experiments of growth-promoting activity in vivo will exacerbate normal cell death. 1994 John Wiley & Sons, Inc.     

Bioelectric Control of Locomotion in the Ciliates*†

SYNOPSIS. Locomotor behavior in the ciliate protozoa is controlled by the cell membrane through electrophysiological principles already familiar in receptor, nerve, and effector cells of the metazoa. This is illustrated by the avoiding reaction (15). When the membrane of the anterior part of the ciliate receives a mechanical stimulus, as during collision, it permits a local influx of Ca⁺⁺. This constitutes a receptor current which depolarizes the remaining cell membrane by electrotonic spread. Depolarization causes a secondary transient increase in the calcium conductance of the entire cell membrane, and a general influx of Ca⁺⁺ occurs. The resulting increase in concentration of intracellular Ca⁺⁺ activates a reorientation (“reversal”) of the ciliary power stroke, causing the organism to swim backward. Forward locomotion is restored as the resting concentration of intracellular Ca⁺⁺ in the cell cortex is restored by diffusion, active extrusion, or intracellular sequestering. The control and coordination of locomotion in ciliates depend on several factors in addition to the excitable properties of the membrane. These include the sensitivities of the ciliary apparatus to intracellular concentrations of calcium and other regulating substances, the anatomical distribution of sensory receptor properties of the cell membrane, and the cable properties of the cell which permit electrotonic spread of graded potential signals without need of all-or-none conducted signals.     

Acoustic Signals of a Dog and Cat Induce Hemodynamic Responses within the Human Brain

The objective of this study was to evaluate the response of the human frontal cortex when listening to cat meows and dog barks, accompanied with a non-verbal pictorial using an affective rating system that assesses the dimensions of valence and arousal. Each participant (24 students; 12 females and 12 males) sat individually in the middle of a room and listened to the sounds (cat meows, dog barks, and the sound of a train) through ceiling-mounted speakers with a near infrared spectroscopic (NIRS) device. Participants had significantly higher oxygenated hemoglobin (oxy-Hb) levels during the exposure to meows (p < 0.05) and barks (p < 0.01) compared with the train sound. A significant correlation was observed between the dimensions of valence and oxy-Hb activation when the participants listened to cat meows (r = 0.53, p < 0.017; Bonferroni correction). In conclusion, we found that the acoustic signals of companion animals lead to frontal cortex responses in humans, suggesting that their signals have an important function related to their long coexistence with people.     

Development and Localization of the Thymidine Phosphorylating Systems in Brain

Abstract: The development of the thymidine phosphorylating systems was studied in various regions of brain. Brain slices from cerebellum, brain stem, and forebrain of rabbits 2, 7, 14, 30, 90, 500, and 2500 days of age were incubated for various times in artificial CSF containing 3 nM-[³H]thymidine at 37°C under 95% O₂-5% CO₂. When slices from all brain regions of 2-day-old rabbits were incubated in [³H]thymidine for 30 min, tissue-to-medium ratios of ³H were between 2 and 4 and declined with age, and the percentages of the total ³H in perchloric acid homogenates of brain slices as [³H]DNA were 26–29%, declining to low levels with age. However, at all ages and in all regions studied, 41 -88% of the ³H within the slices was phosphorylated. After homogenization and subcellular fractionation of the brain slices incubated in [³H]thymidine for 30 min, the highest percentage of [³H]thymidine phosphates plus [³H]DNA was present in the nuclear (crude and purified) and mitochondrial fractions of all brain regions. The [³H]DNA content in the nuclear and mitochondrial fractions declined with age, but the percentage of [³H]thymidine phosphates did not. Thymidine phosphates were synthesized from thymidine in all brain regions tested throughout the entire life span.     

Motivation and Benefits of Complex Systems Approaches in Ecology

Studies of complex systems in other disciplines provide models and analytical strategies for understanding ecosystems and landscapes. The emphasis is on invariant properties, particularly processes that create scaling relations over wide ranges of scale, both in time and space. Translations between levels of ecological organization may be accomplished by succinct characterizations of processes that operate at fine scales, followed by renormalization group analysis to reveal patterns at broad scales. The self-organized patterns found in simple ecosystem, landscape, and forest-fire models may be explained as feedback between the system state and control parameters. Critical phenomena and phase transitions are expected in open, dissipative systems where long-range correlations defy predictions based on average population densities, a concept that becomes irrelevant as nonstationary conditions prevail. Thus, complexity theory for open systems relates to the ecology of self-entailing ecosystems that function as their own environments and thereby create constraints through emergence. Received: 14 April 1998; accepted 26 May 1998     

Virulence Factors of Pseudomonas aeruginosa Induce Both the Unfolded Protein and Integrated Stress Responses in Airway Epithelial Cells

Pseudomonas aeruginosa infection can be disastrous in chronic lung diseases such as cystic fibrosis and chronic obstructive pulmonary disease. Its toxic effects are largely mediated by secreted virulence factors including pyocyanin, elastase and alkaline protease (AprA). Efficient functioning of the endoplasmic reticulum (ER) is crucial for cell survival and appropriate immune responses, while an excess of unfolded proteins within the ER leads to “ER stress” and activation of the “unfolded protein response” (UPR). Bacterial infection and Toll-like receptor activation trigger the UPR most likely due to the increased demand for protein folding of inflammatory mediators. In this study, we show that cell-free conditioned medium of the PAO1 strain of P. aeruginosa, containing secreted virulence factors, induces ER stress in primary bronchial epithelial cells as evidenced by splicing of XBP1 mRNA and induction of CHOP, GRP78 and GADD34 expression. Most aspects of the ER stress response were dependent on TAK1 and p38 MAPK, except for the induction of GADD34 mRNA. Using various mutant strains and purified virulence factors, we identified pyocyanin and AprA as inducers of ER stress. However, the induction of GADD34 was mediated by an ER stress-independent integrated stress response (ISR) which was at least partly dependent on the iron-sensing eIF2α kinase HRI. Our data strongly suggest that this increased GADD34 expression served to protect against Pseudomonas-induced, iron-sensitive cell cytotoxicity. In summary, virulence factors from P. aeruginosa induce ER stress in airway epithelial cells and also trigger the ISR to improve cell survival of the host.     

Cellular Localization of Aquaporin-1 in the Human and Mouse Trigeminal Systems

Previous studies reported that a subpopulation of mouse and rat trigeminal neurons express water channel aquaporin-1 (AQP1). In this study we make a comparative investigation of AQP1 localization in the human and mouse trigeminal systems. Immunohistochemistry and immunofluorescence results showed that AQP1 was localized to the cytoplasm and cell membrane of some medium and small-sized trigeminal neurons. Additionally, AQP1 was found in numerous peripheral trigeminal axons of humans and mice. In the central trigeminal root and brain stem, AQP1 was specifically expressed in astrocytes of humans, but was restricted to nerve fibers within the central trigeminal root and spinal trigeminal tract and nucleus in mice. Furthermore, AQP1 positive nerve fibers were present in the mucosal and submucosal layers of human and mouse oral tissues, but not in the muscular and subcutaneous layers. Fluorogold retrograde tracing demonstrated that AQP1 positive trigeminal neurons innervate the mucosa but not skin of cheek. These results reveal there are similarities and differences in the cellular localization of AQP1 between the human and mouse trigeminal systems. Selective expression of AQP1 in the trigeminal neurons innervating the oral mucosa indicates an involvement of AQP1 in oral sensory transduction.     

Dominance and feeding interference in small groups of blackbirds

Dominance and/or interference parameters play a pivotal rolein most ideal free distribution models, but there has beenscant empirical study of the exact manner in which they jointlyoperate. We investigate how foraging effort and success variedamongst individuals of different dominance rankings in groupsof 1-3 wild blackbirds (Turdus merula) attracted to patchesof hidden food. Foraging effort (number of feeding movementsper unit time), as opposed to vigilance tradeoffs, was greaterwhen an individual fed with a subordinate conspecific thanwhen it fed alone, but tended to be less when it fed with adominant individual. Within dyads, changes in foraging effortwere associated with the direction of the dominance relationship,but not the relative difference in dominance rank between thetwo individuals. Similarly, amongst threesomes, top-rankedbirds (but not the lowest-ranked individual) showed higherforaging effort compared to when foraging alone. Top-ranked birds also profited from a greater increase in foraging success(food items per unit effort) than bottom-ranked birds whenfeeding in threesomes than when feeding alone. Dominant birdsshowed increased foraging success, but not effort, after displacinga subordinate. Our results suggest that an individual's foragingeffort is determined by the interplay of group vigilance benefitsand interference costs, the latter being more expensive for subordinate individuals. The foraging success of dominant birdsmay further increase if they use subordinates as food-finders.We discuss the implications of our findings for interferenceparameters in current Ideal Free Distribution models.     

重庆四面山常绿阔叶林建群种种子雨、种子库研究

对重庆四面山常绿阔叶林建群种种子雨、种子库的研究表明,建群种早期和晚期的种子雨无活力;种子偏早或偏晚成熟及大籽粒的树种,其种子雨被取食的比例大;种子雨、有活力种子雨、种子库三者的数量变化不一致;有活力种子雨量较大的栲、石栎、小叶青冈、扁刺栲、香桂等,其种子库密度在早期以近几何级数的方式增长,元江栲、银木荷种子库小,存在时间短,翌年无一年生萌发苗;种子库数量动态、消减率动态决定于种子被取食的强度、种子衰老的速度以及种子对病菌、逆境的抗性和种子萌发的整齐性.     

Excretory and Secretory Proteins of Naegleria fowleri Induce Inflammatory Responses in BV‐2 Microglial Cells

Naegleria fowleri, a free‐living amoeba that is found in diverse environmental habitats, can cause a type of fulminating hemorrhagic meningoencephalitis, primary amoebic meningoencephalitis (PAM), in humans. The pathogenesis of PAM is not fully understood, but it is likely to be primarily caused by disruption of the host's nervous system via a direct phagocytic mechanism by the amoeba. Naegleria fowleri trophozoites are known to secrete diverse proteins that may indirectly contribute to the pathogenic function of the amoeba, but this factor is not clearly understood. In this study, we analyzed the inflammatory responses in BV‐2 microglial cells induced by excretory and secretory proteins of N. fowleri (NfESP). Treatment of BV‐2 cells with NfESP induced the expression of various cytokines and chemokines, including the proinflammatory cytokines IL‐1α and TNF‐α. NfESP‐induced IL‐1α and TNF‐α expression in BV‐2 cells were regulated by p38, JNK, and ERK MAPKs. NfESP‐induced IL‐1α and TNF‐α production in BV‐2 cells were effectively downregulated by inhibition of NF‐kB and AP‐1. These results collectively suggest that NfESP stimulates BV‐2 cells to release IL‐1α and TNF‐α via NF‐kB‐ and AP‐1‐dependent MAPK signaling pathways. The released cytokines may contribute to inflammatory responses in microglia and other cell types in the brain during N. fowleri infection.     

Phylogenetic Relationships of Blepharisma Americanum and Colpoda Inflata Within the Phylum Ciliophora Inferred From Complete Small Subunit Rrna Gene Sequences

ABSTRACT The complete small subunit rRNA gene sequences of the heterotrich Blepharisma americanum and the colpodid Colpoda inflata were determined to be 1719 and 1786 nucleotides respectively. the phylogeny produced by comparisons with other ciliates indicated that C. inflata is allied more closely with the nassophoreans and oligohymenophoreans than the spirotrichs. This is consistent with the placement of the colpodids in the Class Copodea. Blepharisma americanum was not grouped with the hypotrichs but instead was placed as the earliest branching ciliate. the distinct separation of B. americanum supports the elevation to class status given the heterotrichs based on morphological characters.     

人工诱导兴国红鲤三倍体最佳诱导条件的研究

采用冷休克处理兴国红鲤受精卵诱导产生三倍体鱼 ,初步探讨了获得三倍体兴国红鲤的最佳诱导条件 ,即最恰当的诱导温度 ,最恰当的诱导起始时间 ,最恰当的冷休克处理时间。结果表明 ,在人工授精后 5～ 8min ,将受精卵置于 0～ 2℃的冰水中冷休克处理 1 0～ 1 5min ,再迅速回温至正常水温 ( 2 0～ 2 5℃ )的水中发育 ,可以获得 ( 70± 5) %的三倍体兴国红鲤胚胎 ,孵化率为 50 %～ 70 % ,成活率可达 4 0 %～50 %以上 ,此为采用冷休克技术人工诱导兴国红鲤三倍体的最佳条件。