Total Absence Of Light Research Articles

Diaspores biometry, temperatures and light regime on seed germination of Ptychosperma macarthurii (Arecaceae)

This work aimed to analyze diaspores biometric characteristics, the effect of different temperatures and light regimes on seed germination and on the initial seedlings’ growth of Ptychosperma macarthurii. The experiment was performed at the Horticulture Seed Laboratory, UNESP/FCAV, Jaboticabal, SP. The individual diaspores biometric analysis was performed by measuring the length, diameter, mass and weight of a thousand diaspores, the data were subjected to descriptive statistical analysis. It was adopted a completely randomized design in a 5 × 2 factorial with four replications of 25 seeds per treatment. Five temperatures (25; 30; 35; 20-30 and 25-35 ºC) and two light regimes (presence and total absence of light) were evaluated. The variables analyzed were germination, germination speed index, average length of the primary root and shoot, diameter of the stem and seedlings total dry mass. The length, diameter and average weight of the diaspores were 12.54 mm, 6.05 mm and 0.1610 g, respectively. The seeds of Ptychosperma macarthurii germinated in a wide temperature range, reaching a higher germination percentage at 25 ºC and a higher germination speed index at 30 ºC, being classified as neutral photoblastics. The constant temperature of 30 ºC provided higher mean values ​​for all seedlings’ biometric characteristics.

Absence of Light Exposure Increases Pathogenicity of Pseudomonas aeruginosa Pneumonia-Associated Clinical Isolates.

Simple SummaryAn often-overlooked factor when designing an experiment is light exposure. Bacterial cultures are usually grown in an uncontrolled light environment, subject to natural daylight conditions. However, light as an abiotic factor has been described as a trigger for the switch from environmental to a pathogenic host-associated lifestyle. Pseudomonas aeruginosa possesses features that allow it to sense light and adapt its behavior accordingly. In this study, clinical isolates of P. aeruginosa from the sputum of pneumonia-diagnosed patients were assayed in two extreme light exposure conditions: constant illumination and intensity of full-spectrum light, and complete absence of light. The aim was to understand the influence of this factor on P. aeruginosa pathogenic potential, studied in interface with a human pulmonary epithelial cell line model. The preliminary findings here described evidenced that growth in the dark, which would more closely mimic the conditions in the lung microenvironment, was associated with a higher cytotoxicity against host cells, concordant with an increased pathogenic potential. Given the importance of accurately interpreting bacterial responses in in vitro studies, this study raises awareness of the need to control light exposure conditions to be as similar as possible to in vivo parameters.Pseudomonas aeruginosa can alter its lifestyle in response to changes in environmental conditions. The switch to a pathogenic host-associated lifestyle can be triggered by the luminosity settings, resorting to at least one photoreceptor which senses light and regulates cellular processes. This study aimed to address how light exposure affects the dynamic and adaptability of two P. aeruginosa pneumonia-associated isolates, HB13 and HB15. A phenotypic characterization of two opposing growth conditions, constant illumination and intensity of full-spectrum light and total absence of light, was performed. Given the nature of P. aeruginosa pathogenicity, distinct fractions were characterized, and its inherent pathogenic potential screened by comparing induced morphological alterations and cytotoxicity against human pulmonary epithelial cells (A549 cell line). Growth in the dark promoted some virulence-associated traits (e.g., pigment production, LasA proteolytic activity), which, together with higher cytotoxicity of secreted fractions, supported an increased pathogenic potential in conditions that better mimic the lung microenvironment of P. aeruginosa. These preliminary findings evidenced that light exposure settings may influence the P. aeruginosa pathogenic potential, likely owing to differential production of virulence factors. Thus, this study raised awareness towards the importance in controlling light conditions during bacterial pathogenicity evaluation approaches, to more accurately interpret bacterial responses.

Germinative characteristics of tamarillo seeds (Solanum betaceum Cav.) from red and orange fruits

This study appears in the context of the application of germination tests to samples of tamarillo (Solanum betaceum Cav.) seeds of the red and orange strains, post-harvest of the ripe fruits, to serve as a comparison term to the viability tests of ex situ seeds conserved. Germination tests were carried out in Petri dishes with two treatments that were distinguished by the total absence of light and a photoperiod of 16h of light and 8h of darkness, in a total of six repetitions of ten seeds. The results showed the existence of differences in promotion of Solanum betaceum seeds germination. The germination conditions were decisive, being evident that there is sensitivity to light from the seeds of this species.

Sharing the space: coexistence among terrestrial predators in Neotropical caves

ABSTRACTThe subterranean environment has a set of unique characteristics, including low thermic variation, high relative humidity, areas with total absence of light and high dependence on nutrient input from the epigean environment. Such characteristics promote distinct ecological conditions that support the existence of unique communities. In this work, we studied seven caves in the Presidente Olegário municipality, Minas Gerais state, Southeast Brazil, to determine their richness of predatory species, to understand how they are spatially distributed in the cave and whether their distribution is influenced by competition and/or predation. We carried out five surveys of the caves, with each cave divided into sampling plots. We collected fauna within the plots using a manual search method. The collected animals were fixed in 70% ethanol for later identification. We performed a canonical correspondence analysis to verify the spatial distribution and substrate preference of each species, and selected five species for agonistic interaction testing in the laboratory. We found a great richness of predators in the caves, with 79 species distributed among 22 families of spiders, five families of pseudoscorpions, three families of chilopods, two families of opilionids and one family each of scorpions and heteroptera. Spiders were the most species diverse and abundant of all arthropods we found in the caves. We recorded evidence of competition among some pairs of species but, in general, the spatial distribution of the predatory community in the interior of the caves seems to be unrelated to interspecies competition. The laboratory pairings support our field observations that most species merely share space, rather than exhibiting aggressive or predatory behaviour.

The Method of Teaching and Examination for Individuals with Visual Impairments: the System in India and Japan

(ProQuest: ... denotes non-US-ASCII text omitted.)...AbstractIntroduction: Education of children with special needs is an important field of study. Children with special needs deserve to be educated like any other human being. Over the years, several provisions have been made and laws have been passed to ensure education of children with special needs. A visually impaired child's needs and goals for learning are not different from that of his sighted peers. Only the means of achieving those goals are different.Objective: The purpose of this study was to compare the prevalent method of teaching and the system of examination for students with Visual Impairment studying in the special schools for the blind in India and Japan.Methodology: The study was delimited to i) blind students only and ii) the special schools for the blind in Kolkata and Tokyo. Purposive sampling technique was used to select 50 teachers (25 each from the special schools for the blind in Kolkata and Tokyo). The researcher interviewed the teachers. Semi-structured information schedules were used to collect data and the data were analyzed only qualitatively.Findings: The method of teaching the blind students was similar in both Kolkata and Tokyo. Differences were observed mainly in the type of teaching equipments used. Regarding the system of examination, differences were observed within the special schools in Kolkata. In Tokyo, however, all the special schools followed a uniform system. The study revealed that in Kolkata a strict pass/fail criterion existed. In Tokyo, on the other hand, there was no strict pass/fail criterion.Conclusion: This study is important because not many comparative studies have been done between India and Japan. Most of the comparative research work is either between Japan and the U.S.A or between Japan and the U.K. This study was conducted mainly to find out the differences between a Developing and a Developed nation. Being a developed country, it is always assumed that there will be a lot to learn from Japan. Through this research study an attempt has been made to find out whether this assumption is true and if it is true then, to what extent the system can be implemented and practiced in the Indian scenario.Keywords: Method of teaching, system of examination, special schools for the blind, Kolkata, TokyoIntroductionEducation in its broadest sense aims to develop and enrich total personality of an individual by providing a well-rounded programme of academic excellence, vocational orientation and cultural fulfillment. Education has to be organized on grounds of utility. It is education which helps a person in realizing his/her potentials and nurturing them (1). A person who is different from the average is entitled to education which would be suited to his unique needs. Education and proper training enables a person to overcome his/her disability and establish himself/herself as a contributing and an independent member of the society.Vision refers to a person's ability to see finer details or clearly distinguish forms at varying distances. The Rehabilitation Council of India Act (1992) stipulated that a Visually Handicapped person means a person who suffers from any of the following conditions, namely:1. Total absence of light;2. Visual acuity not exceeding 20/200 (Snellen Chart) in the better eye with the correcting lenses; or3. Limitation of the field of vision subtending an angle of 20 degree or worse. (2)According to the Law for the Welfare of Physically Disabled Persons in Japan, visual impairment is defined clinically in terms of:1. Visual acuity (as measured in accordance with the International Vision Chart and measured degree of correctness; hereafter the same) of both eyes being 0.1 or less;2. Visual acuity of one eye at 0.02 or less and the other at 0.6 or less;3. Visual field diameter 10 degree or less of both eyes;4. …

Performance of Pacific white shrimp Litopenaeus vannamei raised in biofloc systems with varying levels of light exposure

Most research on biofloc systems has been performed in greenhouses with abundant natural light. The functionality of these systems in an environment devoid of light remains poorly understood, especially with regard to growth and survival of reared animals. This study evaluated the performance of Litopenaeus vannamei reared in a biofloc system with varying levels of light. Treatments were 24h with light (24WL), 12h with light/12h without light (12WL/12WOL), and 24h without light (24WOL), each with four replicate tanks. The 24WL and 12WL/12WOL treatments were supplied with light intensity of 10000lx. Shrimp with mean±SD initial weight of 3.3±0.1g were reared in 850L-tanks at a density of 300shrimpm−3. With the exception of nitrate, TSS, VSS and chlorophyll a, there were no significant differences (P>0.05) in water quality parameters among treatments. Nitrate was higher (P<0.05) in 24WOL treatment than in 24WL but neither was significantly different from 12WL/12WOL. TSS and VSS were higher (P<0.05) in 24WL treatment than 24WOL, but were not significantly different from 12WL/12WOL treatment. Chlorophyll a was higher (P<0.05) in 24WL treatment than in 12WL/12WOL and 24WOL treatments. There were no significant differences (P>0.05) in shrimp survival and feed conversion ratios among the treatments. However, shrimp in 24WL treatment grew at a significantly greater rate and reached a significantly greater final weight than shrimp in 24WOL treatment (P<0.05), but neither was significantly different from 12WL/12WOL. The results demonstrate that shrimp production was higher in the treatment that were exposed to light; however Pacific white shrimp can be raised in total absence of light with acceptable performance.

Infectious Diseases Associated with Caves

In recent times, caving has become increasingly popular, with almost 2 million people visiting national park caves each year in the United States. Although the 2 million tourist visits are extremely low risk, smaller numbers of sport cavers are at risk for some high risk conditions, and expedition cavers are at risk for some obscure infections. Infectious diseases like histoplasmosis, rabies, leptospirosis, and tick-borne relapsing fever may be transmitted by the underground fauna. To reduce the risk of illness or injury while caving, knowledge of potential risks before engaging in this activity is important. Caving preparation needs to be carefully planned and executed, including vaccinations, prophylactic medications, and advice regarding safe conduct and behaviors.

Anaerobic animals from an ancient, anoxic ecological niche

Tiny marine animals that complete their life cycle in the total absence of light and oxygen are reported by Roberto Danovaro and colleagues in this issue of BMC Biology. These fascinating animals are new members of the phylum Loricifera and possess mitochondria that in electron micrographs look very much like hydrogenosomes, the H2-producing mitochondria found among several unicellular eukaryotic lineages. The discovery of metazoan life in a permanently anoxic and sulphidic environment provides a glimpse of what a good part of Earth's past ecology might have been like in 'Canfield oceans', before the rise of deep marine oxygen levels and the appearance of the first large animals in the fossil record roughly 550-600 million years ago. The findings underscore the evolutionary significance of anaerobic deep sea environments and the anaerobic lifestyle among mitochondrion-bearing cells. They also testify that a fuller understanding of eukaryotic and metazoan evolution will come from the study of modern anoxic and hypoxic habitats.

Superação da dormência e qualidade de luz na germinação de sementes de Murdannia nudiflora (L.) Brenans

O estudo da fisiologia germinativa de sementes, principalmente de plantas daninhas, tem se intensificado, devido à importância do conhecimento sobre este assunto para melhorar e criar novas técnicas de manejo de plantas daninhas. Os experimentos foram conduzidos em duas etapas objetivando-se estudar os efeitos de diferentes métodos de quebra de dormência das sementes e da qualidade da luz de Murdannia nudiflora (L.) Brenans. Na primeira etapa, os tratamentos constituíram de sete métodos de quebra de dormência: escarificação mecânica, com lixa por 60 segundos; escarificação química, com imersão em ácido sulfúrico por 30, 60 e 300 segundos, hidróxido de sódio a 20% por 5, 15 e 25 minutos, hipoclorito de sódio a 2,5% por 24 horas, nitrato de potássio (20 mM) por 24 e 48 horas, ácido giberélico (1 mM) por 24 horas e testemunha. O delineamento estatístico utilizado foi o inteiramente ao acaso, com quatro repetições. Foram contadas diariamente as sementes germinadas, e no final de 30 dias, determinou-se o IVG. Na segunda etapa, os tratamentos de qualidade da luz constaram de 5 filtros de luz (azul, verde, vermelho, transparente e ausência total de luz). Maior porcentagem de germinação das sementes foi obtida utilizando escarificação mecânica (lixa) (84%), seguido da escarificação química com ácido sulfúrico por 1 minuto (74%), hipoclorito de sódio por 24 horas (46%) e hidróxido de sódio por 25 minutos (26%). Quanto a porcentagem de germinação de sementes em função da qualidade de luz verificou-se as seguintes porcentagens de germinação: azul - com refletividade máxima a 450 nm (58%), verde - 500 nm (64%), vermelho - 700 nm (75%), ausência de luz (0%) e transparente - sem absortividade na região de 380 nm a 760 nm (87%). Sementes de M. nudiflora podem ser consideradas fotoblásticas positivas.

Clonagem do abacateiro variedade "Duke 7" (Persea americana Mill.) por alporquia

Foram conduzidos dois experimentos com a finalidade de determinar a possibilidade de clonagem da variedade de abacateiro "Duke 7", por alporquia e a influência do AIB (ácido indol-3-butírico) no processo. Experimento 1 - Alporque em plantas - O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 2L x 4N x 2E, correspondendo à manutenção ou não das plantas à ausência de luz (L), níveis de AIB (N) e tipo de estrutura (E). Nos quatro dias antecedentes à realização da alporquia, 50% das plantas permaneceram na ausência total de luz (L1), e as demais, em condições normais de ripado, 50% de luminosidade (L2). No local anelado, foram aplicadas as concentrações (N) de AIB (ácido indolbutírico): 0; 1.000, 3.000 e 5.000 mg kg-1. O experimento foi realizado em duas estruturas diferenciadas pelo tipo de cobertura: a estrutura um (E1) e a estrutura dois (E2), diferenciadas pela temperatura e intensidade luminosa. Experimento 2- Alporque em plantas adultas após poda drástica - Os alporques foram realizados cinco meses após a poda drástica, quando os ramos possuíam entre 1,5 e 2,0 cm de diâmetro. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial, com 4 tratamentos, caracterizados pelas concentrações de AIB (0; 1.000; 3.000 e 5.000 mg kg-1), com quatro repetições, e cada parcela composta por 10 alporques. Em nenhum dos experimentos, houve enraizamento dos alporques, consequentemente há necessidade de maiores estudos, quanto à clonagem da variedade "Duke 7" para viabilizá-la como porta-enxerto.

Effects of a Color Filter Used in Auriculomedicine on Ultraweak Photon Emission of the Human Body

The human body emits ultraweak photons. It has been demonstrated that feedback regulation of ultraweak photon emission from the hand is detectable utilizing gelatin color filters in complete darkness. Color filters are commonly utilized in auriculomedicine diagnostic procedures based on the radial artery vascular autonomic signal. To evaluate the possibility of an effect by a dark-adapted red filter on (1) local ultraweak human photon emission using different anatomic locations, and (2) on systemic photon emission using one location for red filter exposure and another for photon emission recording. Photon emission of abdomen, forehead, palm, and dorsum of the hand was recorded before and after the presence of a red filter. In addition, photon emission of forehead and dorsum of the hand was recorded before, during, and after the presence of the red filter close to the palm. In both instances, the filter was dark-adapted and placed in close proximity to, but not touching the skin of the dark-adapted subject. A low-noise, end window photomultiplier for recording ultraviolet and visible (200-650 nm) photon emission (with a very low background count rate) and designed for manipulation in three directions was situated in a dark room. The technology was utilized to record spontaneous photon emission of the abdomen, forehead, palm, and dorsum of the hand of one human male subject. Data demonstrate that a dark-adapted subject responds in the total absence of light with a temporary increase in photon emission from the anatomic locations that had been exposed for 200 s at a distance of 3 cm to a dark-adapted red filter. Data from sequential time series suggest red filter initiation of a refractory emission reaction. Exposure of the palm to the red filter also evokes photon emission from the dorsum of the same hand and from the forehead. This response could be registered immediately after the beginning of the exposure. The stimulated emission is followed by a slow decrease of emission in the period after exposure to the filter. Data suggest that red filter-stimulated photon emission response is systemic and rapid. Data imply an exchange of information vis-à-vis light from both hand and red filter. The mechanism of such interaction is currently speculation only.

Reduction and Stabilization of Silver Nanoparticles in Ethanol by Nonionic Surfactants

The reduction of Ag+ ions in ethanol when certain surfactants are also present in the solution is shown to take place, even in the total absence of light. The reduction process leads to dispersions of silver nanoparticles, which are stable for weeks, although they show a certain tendency to stick to glass walls. Several surfactants were tested, showing that there is a dependency on their nature and concentration. Nonionic ethoxylated surfactants proved to be the most effective of all the surfactants tested, the reduction then being due to the oxidation of oxyethylene groups. In any case, the yield is very low (around 1%). Colloidal stability is achieved by adsorption of surfactant molecules onto the particles, which permits easy transfer of the particles into nonpolar solvents. The reduction rate markedly depends in a first-order fashion on silver salt concentration and depends on temperature according to Arrhenius's law. The optical properties of the obtained colloids are influenced by the surfactant molecules attached to the particle surface.

Dye-Sensitized House Fly Toxicity Produced as a Function of Variable Light Sources 1

House fly mortality induced by light after xanthene dye ingestion is dependent upon both light intensity and light source. Three variable light sources were employed in this study including fluorescent light, quartz iodide sunlamp, and the sun, and were compared to the total absence of light. Two dyes, rose bengal and erythrosin B, were tested for toxicity in the absence of light and appear to induce mortality by a similar, but different, mechanism. Six xanthene dyes were investigated for house fly toxicity with three different light sources to determine the relative effectiveness and efficiency of these light sources. The sun was the most effective light source, ca. 3.4 times more effective than fluorescent lights; but when light efficiency is considered, fluorescent lights are nearly 2.5 times more efficient than the sun and 3 times more efficient than the sunlamp.

Internal and external coincidence and the apparent diversity of photoperiodic clocks in the insects

1. Photoperiodic induction of diapause inNasonia vitripennis andSarcophaga argyrostoma was shown to be different in a number of respects. InN. vitripennis induction proceeds to “completion” in continuous darkness after an initial five short-day (long-night) cycles, and can be accomplished in the total absence of light by the use of daily temperature cycles, or thermoperiods.S. argyrostoma, on the other hand, requires repeated exposures to short-day (long-night) cycles for “full” induction, and thermoperiods in the absence of light are apparently ineffective. Furthermore, inS. argyrostoma periods of CO2 and N2 anaesthesia applied during the light and the dark portions of the daily cycle underlined the central importance of night-length measurement, whereas periods of chilling inN. vitripennis had previously shown light and dark to be of equal importance. 2. These results are considered to be consistent with two current models for the photoperiodic clock: internal coincidence (N. vitripennis) and external coincidence (S. argyrostoma), although none of the experimental results offersunequivocal evidence for this conclusion. 3. The apparent diversity of insect photoperiodic clocks is examined, particularly in terms of Pittendrigh's “extended circadian surfaces”. It is considered likely that the apparent diversity is a product of evolutionary divergence from a common ancestral mechanism with its basis in circadian rhythmicity.

The Rhetoric of Black and White in Othello

black in our language and literature had reached explosive pitch, I found the preparation of Othello arduous but illuminating exercise. The repeated use of the terms black and white, with various but always polarized meanings, and the relationship of those terms other suggested and dramatized elements of the play required, indeed demanded, a full explication of the terms and of Shakespeare's use of them in Othello. Such explication suggests that the complex and confusing values of black and are used reinforce the theme of man's tragic blindness in Othello. The terms black and have been complex and confusing since the beginning of the language, and Shakespeare seems have fully exploited their complexity within Othello. According the OED, the origin of the word black is obscure, but seems be related the verb Blaekan, to burn, or scorch, and is used for that color of charcoal which is the total absorption, or the total absence of light; however, the original term, blac, is so close bl4c, meaning shining white-the total reflection or presence of light-that the meanings of the two are not always distinguishable,' even by context. This early confusion of the literal, denotative meanings of the terms is a vivid precursor of possible confusions available by Shakespeare's day when both black and could be accurately used for a wide variety of specific denotations, each with its own range of connotations. Shakespeare not only employed various meanings of the terms and their connotations literally and metaphorically, but also persistently applied the connotations of one meaning of black another meaning of black. In addition, the conflated and confusing values of black that resulted from this treatment are heightened by a similar treatment of the opposite values of white, or, more often, fair. Within Othello, black is used with five explicit denotations, and or fair is posed in each instance, either explicitly or by suggestion, as the opposite quality. First, black is used as a color designation for the darkest hue, an old black ram (I. i. 88)2; white, as the opposite, designates the lightest hue: white ewe (I. i. 89). Second, black. is used designate a Moor, a Negro, one of

Thermoperiodic Control of Diapause in an Insect: Theory of Internal Coincidence

Females of the parasitic wasp Nasonia vitripennis raised from the egg stage in the total absence of light but subjected to daily temperature cycles (13 degrees to 23 degrees C), are able to distinguish a "short-day" thermoperiod ( 13 hours at 23 degrees C per day) from a "long-day" thermoperiod ( 13 hours at 23 degrees C per day) and produce diapausing or developing progeny accordingly.

Protein Synthesis in Chlorella

1. One of the unicellular Chlorophyceae, Chlorella sp., was grown in pure culture in a nutrient solution to which combined nitrogen was supplied in inorganic combination, either as calcium nitrate or ammonium sulphate. 2. Cultures were grown in diffuse light and in the total absence of light for 105 or 235 days. 3. Quantitative determinations were made of the volume, dry weight, and total nitrogen content of the growth obtained. 4. The data obtained offer strong evidence indicating that Chlorella sp. can synthesize proteins in total darkness when nitrogen is supplied in inorganic combination. 5. No evidence of free nitrogen fixation by Chlorella sp. was obtained.

American Cave Vertebrates 1

PROF. EIGENMANN has brought together in an attractive and copiously illustrated quarto volume the results of his investigations on the cave fauna of America, upon which he has been engaged for many years. He points out that each cave is a separate environmental unit requiring special consideration, but all share to a greater or less extent certain common features, viz. the reduction or total absence of light and the relative constancy of other physical conditions, such as temperature.