Variações diurnas da atividade in vivo da redutase do nitrato em abacaxizeiro (Ananas comosus (L.) Merr. - Bromeliaceae)

A análise da atividade enzimática da redutase do nitrato baseou-se no método do ensaio in vivo, que foi padronizado para os tecidos foliares e radiculares do abacaxizeiro cultivado in vitro. As maiores atividades enzimáticas foram obtidas quando se empregou como meio de reação uma solução tampão fosfato 0,1 M, contendo KNO3 100 mM e 3% de n-propanol, a faixa de pH ótimo foi de 6,5 a 7,5. O tempo de incubação foi de 60 min a 30 °C. Essa padronização mostrou-se muito importante para a análise do ritmo diurno da redutase do nitrato em abacaxizeiro, visto que as condições de ensaio in vivo dessa enzima variam muito entre diferentes espécies vegetais. As folhas apresentaram as maiores atividades na presença de luz. As raízes mostraram atividade da redutase do nitrato também na ausência de luminosidade em níveis semelhantes aos observados na presença de luz. A atividade observada nas raízes foi sempre superior à das folhas, sugerindo que as raízes têm um importante papel na redução do nitrato nas condições de cultivo in vitro. O acúmulo de nitrato observado durante o ciclo diurno, nas folhas, evidenciou que a presença desse íon ocorreu em maiores níveis durante o período luminoso, estabelecendo uma correlação positiva com a atividade da redutase do nitrato. Entretanto, nas raízes, as maiores concentrações foram observadas na ausência de luz. Nesse caso, discute-se a possibilidade de outros fatores, além do nitrato, estarem contribuindo positivamente, induzindo uma elevada atividade enzimática na presença de luz.

Spatial distribution and preferential substrate of Neoregelia johannis (Carriére) L.B. Smith (Bromeliaceae) in a disturbed area of Atlantic Rainforest at Ilha Grande, RJ, Brazil

In bromeliad populations, amount of light and available substrates influence individuals spatial organization. In Atlantic Rainforest of Ilha Grande, the heliophylous bromeliad Neoregelia johannis is a large and abundant species. In this forest, it would be expected that N. johannis would occupy stable substrates, as large trunks, large branches, rock boulders or ground, with high sunlight, enough for the bromeliad survivor. In the present work, we analyzed the distribution and most used substrates of N. johannis in secondary forest. We analyzed the frequency of reproductive modes (sexual and vegetative) used by the bromeliad shoots, registering if the shoots were originated from seeds or by vegetative reproduction. The results indicated an aggregated distribution pattern (Ip = 0.052). The preferred substrate was boulders (91%), whereas tree trunks (6%) and the ground (3%) were rarely used. Small and fragile substrates are unstable to support large adults of this species, which may explain the predominant pattern of establishment over boulders within the secondary forest, as the presence of this substrate also results in more opened canopy cover. Approximately 50% of young individuals entered the population by vegetative reproduction. We conclude that the preferential habit and the aggregated distribution of N. johannis are due to the conjunction of preferred substrate with higher amount of light resulting from breaks in tree canopy over areas with rock blocks, and high frequency of recruitment by vegetative reproduction.

Habitat utilization and CAM occurrence among epiphytic bromeliads in a dry forest from southeastern Brazil

We studied the community and habitat occupation of epiphytes to understand how these plants cope with a supposedly stressful habitat: i) how general epiphytes occupy tree trunks, ii) how epiphytic bromeliads, occupy their supportive trees, iii) how CAM bromeliads are spatially distributed. The study was done in the dry forest of Jacarepiá, State of Rio de Janeiro. Data collection on epiphytes, phorophytes, and trees was based on the point-center quarter method. The photosynthetic pathway of the bromeliad species was determined using isotope ratio mass spectrometry. The presence of Gesneriaceae, Araceae, and Cactaceae indicates that some humidity is present in the area allowing the presence of supposedly less-specialized epiphytes. There was no correlation between epiphyte abundance and phorophyte diameter, and phorophytes had larger sizes than trees that do not host epiphytes. There was correlation between tree diameter and bromeliad abundance, and lack of correlation between diameter and bromeliad richness. Only one species was typical of the understorey and one was typical of the canopy, while intermediate heights were occupied by different species. The only C3 bromeliad species (Vriesea procera (Mart. ex Schult.f.) Wittm.) was significantly more exposed than the other species. If CAM occurrence is related to water economy, the fact that a C3 species is subjected to more exposed conditions is remarkable. Further comments are presented on the proportion between CAM bromeliad species and abundance in dry forest. Regarding life forms, holoepiphytes, as opposed to hemiepiphytes, showed not to be restricted by the phorophyte's diameter suggesting a more successful establishment of this life form.

The effect of water stress on seed germination of three terrestrial bromeliads from restinga

Bromeliad seedlings are rarely found on sandy coastal plains (restinga), limited, probably, by stressful conditions and/or specific abiotic requirements for germination. The effect of water stress on rate, time, synchronicity and spreading of germination was evaluated here for three terrestrial bromeliads from the restinga of Maricá using osmotic solutions of polyethyleneglicol 6000 (PEG 6000), from 0.0 to -0.26 MPa for 30 days. Water stress induced by PEG lowered rate and increased time and synchronicity values, besides the number of daily events of bromeliad seed germination, under water potentials between 0.00 to -0.14 MPa. No seeds germinated under water potentials lower than -0.14 MPa. These results reinforce a constant and/or high moisture requirement for bromeliad seeds to germinate. We conclude that bromeliads are not able to act as pioneer plants through germination outside the vegetation islands of the restinga of Maricá, due to the inability of seeds to germinate under lower water potential.

Subgeneric diversity of Brasilonema (Cyanobacteria, Scytonemataceae)

The recently described scytonematoid cyanobacterial genus Brasilonema is known mainly from tropical and subtropical rain forests (Mata Atlântica) of southeastern Brazil, where it occurs in aerophytic wooden, stony and iron substrates. This genus was defined according to both molecular and morphological criteria. The type species B. bromeliae was described from the specialized habitat: it grows in phytothelmes, epiphytic on both living and died leaves within the rosettes of large bromeliad plants slightly above or in the zone of the water level. The genus Brasilonema is evidently widely distributed in coastal forests of São Paulo State, where it occurs also in remarkable diversity. According to our results, this genus currently comprises seven taxa, which are distinct by different morphology and ecological characteristics.

Becoming Locals in a Borderland of Exiles. Sense of Place in the Stories of Lithuania Minor Dwellers

This thesis deals with sense of place, the relation that we construct with our dwelling and the surrounding environment. The topic belongs to the field of human geography. Sense of place is deeply intertwined with the ideas of feeling at home and having a place where to return. I argue that narratives of life experience help us relate to the places we inhabit, go through, leave. My analysis concerns Lithuania Minor, the Lithuanian region lying by the border with Kaliningrad, and focuses in particular on Vilkyškiai, a village in the municipality of Pagėgiai. Most of the area’s original population disappeared in the war. After 1945, people from all over the country and the USSR settled here. This raised the prickly question of who belongs to the borderland. Refugees, migrants and settlers allow us to observe closely the development of sense of place and its main constituents. Through this analysis, I challenge the idea of people’s natural rights to places and shows how time, engagement in local-based cultural activities and recollection help foreigners become locals. To grasp the locals’ sense of place, I collected open, light-structured interviews and applied some elements of semantic analysis to interpret the materials. From my research, it emerges that the cultivation of the region’s cultural heritage and the practice of storytelling were crucial in making the respondents feel at home. Leaving aside all legalistic claims concerning the issue, I suggest that people belong to the land they dwell. I believe that their sense of place deserves consideration from the State and the other actors seeing them as migrants.

Jokapäiväinen design

Kirjallisuusarvostelu

The calcium-dependent protease of Loxosceles gaucho venom acts preferentially upon red cell band 3 transmembrane protein

Eighty micrograms red blood cell (RBC) ghosts from patients who had previously exhibited the cutaneous form of loxoscelism (presenting localized dermonecrosis) and the viscerocutaneous form of loxoscelism (presenting dermonecrosis, hemoglobinuria, hematuria, and jaundice) and from controls were incubated with 2.5 µg crude Loxosceles gaucho venom in 5 mM phosphate buffer, pH 7.4, at 37ºC. Among all membrane proteins, quantitative proteolysis of the important integral transmembrane protein 3 increased with venom dose and with incubation time from 30 to 120 min, as demonstrated by gel densitometry. Similar quantitative data were obtained for RBC ghosts from patients and from control subjects, a fact that argues against the possibility of genetic factors favoring the hemolytic viscerocutaneous form. These data suggest that the clinical forms may be different types of the same disease, with the viscerocutaneous form being the result of large amounts of intravascularly injected venom and the superficial form being the result of in situ venom action. Since protein 3 is a housekeeping integral membrane protein, whose genetic deficiency leads to hemolytic anemia, it is reasonable to relate it to the hemolysis which occurs in the viscerocutaneous form of loxoscelism. The venom protease responsible for the process was not inhibited after 120-min incubation by 0.2 mM paramethylsulfonyl fluoride or by 0.2 mM N-ethylmaleimide but was inhibited by 25 mM ethylenediaminetetraacetic acid (a calcium-chelating agent) in 5 mM phosphate buffer at pH 7.4, which suggests that the enzyme is a calcium-dependent metalloprotease.

"Rakkaat poikaiset!". Simon ja Wilhelmina Janssonin perhekirjeet egodokumentteina (1858-1887)

Kustavilainen talonpoikaislaivuri Simon Jansson ja hänen vaimonsa Wilhelmina o.s. Widbom kävivät kolmenkymmenen vuoden ajan kirjeenvaihtoa kouluun ja yliopistoon lähetettyjen poikiensa Waldemar, Evald ja Emil Jahnssonin kanssa. Lähes 150 suomen- ja ruotsinkielistä kirjettä on säilynyt Suomalaisen Kirjallisuuden Seuran kirjallisuusarkistossa ja Turun maakunta-arkistossa. Lähiluvun kautta kirjeistä muodostuu yksityiskohtainen lähde saaristolaisperheen elämäntapaan, arkeen ja työhön sekä saaristoyhteisön sosiaalisen kanssakäymisen muotoihin. Ne kertovat myös ensimmäisen polven oppisivistyneistön synnystä ja niistä resursseista, joita hyödyntäen koulua käymättömät vanhemmat saattoivat kouluttaa lapsensa. Tutkimus liittyy suomalaisten 1800-luvun itseoppineiden kirjoittajien tekstien ja maaseudun kirjallistumisen tutkimukseen. Keskeinen käsite on egodokumentti, jolla tarkoitetaan kirjeitä ja muita tekstejä, joissa kirjoittaja kertoo itse omasta elämästään. Hollantilainen ja ranskalainen egodokumenttien tutkimus on pyrkinyt haastamaan uudenlaisten lähdeaineistojen kautta käsityksiä menneisyydestä sekä nostamaan esiin muun muassa yksilöllisen kokemuksen, kirjoittamisen kulttuurin ja dokumenttien materiaalisuuden. Janssonin perheen kirjeet poikkeavat monin tavoin 1800-luvun säätyläisten kirjeistä. Niiden funktio oli hyvin käytännöllinen ja arkinen, mutta ne olivat myös vanhempien keino tukea perheen yhteistä sosiaalisen nousun projektia. Kustavia koskevan tiheän uutisoinnin kautta ne pyrkivät pitämään kaupunkilaistuvat pojat osana vanhaa yhteisöään. Perheen isä vastasi suurelta osin kirjeenvaihdosta ja siihen liittyvästä huolenpidosta, mikä kertoo sukupuolittuneen työnjaon joustavuudesta saaristossa. Tutkimus osoittaa, ettei isän ammattiin perustuva yliopisto-opiskelijoiden tutkimus ole tavoittanut sitä naisten kautta välittyvää sosiaalista ja kulttuurista pääomaa, joka saattoi olla ratkaiseva perheiden kouluttaessa lapsiaan. Kirjeiden analyysi tarkentaa kuvaa perinteisen talonpoikaispurjehduksen sopeutumisesta vuosisadan loppupuolen uudistuksiin.

Erectile dysfunction in cardiovascular risk population

The inability to achieve and to maintain erection, erectile dysfunction, is a bothersome symptom of elderly men. Moreover, there is a high comorbidity between cardiovascular diseases and erectile dysfunction. However, very little is known concerning the risk factors of ED in apparently healthy men without comorbidities affecting the arteries. A cross-sectional population survey was conducted from August 2005 to September 2007 in two rural towns of Harjavalta and Kokemäki in Finland. Excluding those with previously diagnosed cardiovascular diseases, diabetes or chronic kidney disease, every community-dwelling inhabitant was invited to take part in the survey. Of the 2939 45- to 70-year-old men invited, 2049 responded. Selecting those at risk for cardiovascular diseases, 1000 eligible men were examined. According to the International Index of Erectile Function short form 57% of the studied men reported erectile dysfunction. Increasing age, smoking, depressive symptoms, decreasing pulmonary function, sedentary lifestyle, non-marital status and low education level were associated with increasing risk of erectile dysfunction. However, hypertension, diabetes, obesity, hypercholesterolemia were not associated with erectile dysfunction, although these associations have been described in numerous previous studies. Moreover, erectile dysfunction was not associated with increasing risk of pre-diabetes. In apparently healthy men, increasing age, smoking, depressive symptoms, decreasing pulmonary function, sedentary lifestyle, non-marital status, low education level but not hypertension, obesity, hypercholesterolemia, diabetes or pre-diabetes were associated with increasing risk of erectile dysfunction.

Phylogenetic Analysis of Avidins and Expression of Novel Avidins from Lactrodectus hesperus and Hoeflea phototrophica

Avidins (Avds) are homotetrameric or homodimeric glycoproteins with typically less than 130 amino acid residues per monomer. They form a highly stable, non-covalent complex with biotin (vitamin H) with Kd = 10-15 M (for chicken Avd). The best-studied Avds are the chicken Avd from Gallus gallus and streptavidin from Streptomyces avidinii, although other Avd studies have also included Avds from various origins, e.g., from frogs, fishes, mushrooms and from many different bacteria. Several engineered Avds have been reported as well, e.g., dual-chain Avds (dcAvds) and single-chain Avds (scAvds), circular permutants with up to four simultaneously modifiable ligand-binding sites. These engineered Avds along with the many native Avds have potential to be used in various nanobiotechnological applications. In this study, we made a structure-based alignment representing all currently available sequences of Avds and studied the evolutionary relationship of Avds using phylogenetic analysis. First, we created an initial multiple sequence alignment of Avds using 42 closely related sequences, guided by the known Avd crystal structures. Next, we searched for non-redundant Avd sequences from various online databases, including National Centre for Biotechnology Information and the Universal Protein Resource; the identified sequences were added to the initial alignment to expand it to a final alignment of 242 Avd sequences. The MEGA software package was used to create distance matrices and a phylogenetic tree. Bootstrap reproducibility of the tree was poor at multiple nodes and may reflect on several possible issues with the data: the sequence length compared is relatively short and, whereas some positions are highly conserved and functional, others can vary without impinging on the structure or the function, so there are few informative sites; it may be that periods of rapid duplication have led to paralogs and that the differences among them are within the error limit of the data; and there may be other yet unknown reasons. Principle component analysis applied to alternative distance data did segregate the major groups, and success is likely due to the multivariate consideration of all the information. Furthermore, based on our extensive alignment and phylogenetic analysis, we expressed two novel Avds, lacavidin from Lactrodectus Hesperus, a western black widow spider, and hoefavidin from Hoeflea phototrophica, an aerobic marine bacterium, the ultimate aim being to determine their X-ray structures. These Avds were selected because of their unique sequences: lacavidin has an N-terminal Avd-like domain but a long C-terminal overhang, whereas hoefavidin was thought to be a dimeric Avd. Both these Avds could be used as novel scaffolds in biotechnological applications.

Cholesterol, cardiovascular disease and statin use in older persons

Older age increases the risk of developing a chronic atherosclerotic cardiovascular disease (CVD), such as coronary heart disease. Complications of CVDs, myocardial infarction or stroke often lead to loss of functional capacity or premature death. Dyslipidemia, high serum levels of total or low-density lipoprotein cholesterol (LDL-c) and low levels of high-density lipoprotein cholesterol (HDL-c), is among the most important modifiable risk factors for CVDs; it can be treated with lifestyle modifications, and with lipid-lowering drugs, primarily statins. In older persons, however, the association of cholesterol levels with cardiovascular and all-cause mortality has been inconsistent in previous studies. Furthermore, the beneficial effects of statins in older persons without previous CVD are still somewhat unclear, and older persons are more prone to adverse effects from statins. This thesis presents a prospective cohort study (TUVA), exploring associations of cholesterol levels with mortality and the changes in cholesterol levels of a 70-year-old population in long-term follow-up. Further, prevalence of CVDs, risk factors and preventive medication use in the TUVA cohort is compared with respective prevalences in another age-matched cohort (UTUVA) 20 years later in order to examine the changes in cardiovascular risk over time. Additionally, to evaluate statin use patterns among older persons, an observational register study was conducted covering the total Finnish population aged 70 and older during 2000-2008. Based on individual-level data retrieved from national health registries, the population was classified into low, moderate and high risk groups according to estimated CVD risk. The prevalence, incidence and persistence of statin use among the risk groups was then evaluated based upon yearly statin purchases tracked from the Prescription Register. The prospective cohort study demonstrated that low total cholesterol, LDL-c and HDL-c were associated with higher mortality in a cohort of home-dwelling 70-year-olds. However, after adjusting for traditional cardiovascular risk factors and cancer this association disappeared. Further, low total cholesterol seemed to be protective, whereas low HDL-c strongly predicted increased risk of CVD death. Cholesterol levels of those elderly who remained available for follow-up and were still home-dwelling at the age of 85 seemed to improve with advancing age. Compared to the TUVA cohort, the later born UTUVA cohort had less CVDs and their risk factors were better controlled, which was reflected in the higher use of preventive medications such as statins and antihypertensives. The register studies confirmed that statin use has increased significantly during 2000-2008 among older persons, especially among the oldest (80+) age groups and among those at high risk for cardiovascular events. Two-thirds of new statin users persisted with their use during the four years of follow-up; the most discontinuations were made during the first year of use. In conclusion, statins are commonly used among older age groups in Finland. Most of the older statin users had a high cardiovascular event risk, indicating that the treatment is well directed towards those who are likely to benefit from it the most. No age-limits should be put on the screening and treatment of dyslipidemia in older persons, but the benefits and adverse effects of statin treatment should be carefully weighed based on an individual assessment of the person’s general health status and functional capacity. Physicians should pay more attention to medication adherence, especially when prescribing preventive medications.

The effect of a weighted-vest strength and balance training program on obstructed walking in postmenopausal women

SUMMARY Background: Age related declines in lower extremity strength have been associated with impaired mobility and changes in gait patterns, which increase the likelihood of falls. Since community dwelling adults encounter a wide range of locomotor challenges including uneven and obstmcted walking surfaces, we examined the effect of a strength 11 and balance exercise program on obstructed walking in postmenopausal women. Objectives: This study examined the effect of a weighted-vest strength and balance exercise program on adaptations of the stance leg during obstacle walking in postmenopausal women. Methods: Eighteen women aged 44-62 years who had not engaged in regular resistance training for the past year were recruited from the St. Catharines community to participate in this study. Eleven women volunteered for an aerobic (walking), strength, and balance training program 3 times per week for 12 weeks while 7 women volunteered as controls. Measurements included: force platform dynamic balance measure of the center of pressure (COP) and ground reaction forces (GRFs) in the stance leg while going over obstacles of different heights (0,5, 10,25 and 30 cm); and isokinetic strength measures of knee and ankle extension and flexion. Results: Of the 18 women, who began the trial, 16 completed it. The EX group showed a significant increase of 40% in ankle plantar flexion strength (P < 0.05). However, no improvements in measures of COP or GRFs were observed for either group. Failure to detect any changes in measures of dynamic balance may be due to small sample size. Conclusions: Postmenopausal women experience significant improvements in ankle strength with 12 weeks of a weighted-vest balance and strength training program, however, these changes do not seem to be associated with any improvement in measures of dynamic balance.

Effects of a hydroxy-cinnamoyl conjugate of spermidine in the neuromuscular junction of crayfish /

N'-coumaroyl spermidine (NlCSpd) is a plant derived chemical which is proposed to belong to a class of low molecular weight neuroactive substances called phenolic polyamines. NlCSpd is stnicturally similar to glutamate receptor blocking toxins found in certain spiders and wasps, such as JSTX-3 and NSTX-3 found in Nephila spiders. The goal of the present study was to determine if plant-derived phenolic polyamines act like other structurally related chemicals found in Arthropod venoms, such as JSTX-3, and whether they can be classified in the same pharmacological group as the spider and wasp toxins. A comparison was made to determine the relative potencies of various phenolic polyamines fi-om plants and insect venoms. This comparison was done by measuring the effect of various concentrations ofNlCSpd on the amplitude of excitatory postsynaptic potentials (EPSPs) elicited in muscle of the crayfish Proccanbarus clarkii. NlCSpd was also tested on L-glutamate induced potentials to determine if a postsynaptic component to sj^naptic block occurs. NlCSpd and an analogue with an a longer polyamine chain, NlCSpm, blocked EPSPs in a dose dependent manner, NlCSpd having an IC50 of lOOnM. NlCSpd also blocked L-glutamate induced potentials. The two main components of the NlCSpd molecule alone are insufficient for activity. NlCSpd acts postsynaptically by interfering with crayfish glutamatergic synaptic transmission, likely blocking glutamate receptors by interacting with the same site(s) as other phenolic polyamines. Certain moieties on the polyamines molecule are necessary for activity while others are not.

Out of the darkness and into the light : a study of inauthentic and authentic speech

Introduction Man can be described as the being who shows himself in speech, and from birth to death is continually speaking. Communication is so close to us, so woven into our very being, that we have little understanding of the way it is constituted; for it is as hard to obtain distance from communication as it is to obtain distance from ourselves. All communication is not alike. There are two basic modesl of communication, the inauthentic and the authentic, between which there occurs a constant tension. It is in the inauthentic mode, points out Heidegger, that we find ourselves "proximately and for the most part"; 1. Being and Time, pg. 68 Dasein decides as to the way it will comport itself in taking up its task of having being as an issue for it. " •.• it~, in its very being 'choose' itself and win itself; it can also lose itself and never win itself or only "seem" to do so. But only in so far as it is essentially something which can be authentic--that is, something of its own--can it have lost itself and not yet won itself." 2. therefore Heidegger also terms it "everydayness".2 Caught up in the world of everydayness, our speaking covers over and conceals3 our rootedness in being, leaving us in the darkness of untruth. The image of darkness may be inferred from Heidegger's use of the image of "clearing,,4 to depict being as 2. ibid. pg. 69 "Dasein's average everydayness, however, is not to be taken as a mere 'aspect'. Here too, and even in the mode of inauthenticity, the structure of existentiality lies ~ priori and here too Dasein's being is an issue for it in a definite way; and Dasein comports itself towards it the mode of average everydayness, even if this is only the mode of fleeing in the face of it and forgetfulness thereof." 3. ibid. pg. 59 "covering over" and "concealing" are 1;yays Dasein tries to flee its task of having being as an issue for itself. " ••• This being can be covered up so extensively that it becomes forgotten and no question arises about it or its meaning ••• n How everyday speaking accomplishes this will be taken up in detail in the second chapter which explores Dasein's everyday speech. 4. ibid, pg. 171 lI ••• we have in mind nothing other than the Existential - ontological structure of this entity (Dasein), that it is in such a way as to be its 'there'. To say that it is -' illuminated' [tlerleuchtet"] means that as Being-in-theworld it is cleared [gelichtetJ in itself7 not through any other entity, but in such a way that it is itself the clearing. Only for an entity which is eXistentially cleared in this way does what is present-at-hand become accessible in the light or hidden in the dark •••• " 3 dis-coveredness and truth. Our first task will be to explore the nature of communication in general and then to explore each of the modes manifested in turn. The structure of the inauthentic mode of communication can be explored by asking the following questions: What is this speaking about? Who is it that is speaking and who is spoken to? Does this speaking show man in his speech? The authentic mode is distinguished by the rarity with which we encounter it; as the inauthentic conceals, so the authentic reveals our rootedness in being. Yet this rarity makes it difficult to delineate its elusive structure clearly. Its constituent elements can be brought into focus by asking the same questions of this mode that we previously asked of the inauthentic mode. Our initial response to the disclosure of the authentic mode is to attempt to abandon the inauthentic mode and leave the darkness behind dwelling only in the "lighted place". All through the ages, some men pushing this to extreme, have, upon uncovering their relatedness to being, experienced a deep longing to dwell in such a "place" of pure truth and oft times denigrated or attempted to exclude the everyday world. Such 4. flight is twice mistaken: first it atbempts to fix truth as unchanging and static and secondly, it opposes this to untruth which it seeks to abolish. This is both the wrong view of truth and the wrong view of untruth as Heidegger points out in The Origin of The-Work of Art: The Way-to-be of truth, i.e., of discoveredness, is under the sway of refusal. But this refusal is no lack or privation, as if truth could be simply discoveredness rid of all covers. If it could be that, it would no longer be itself . ••• Truth in its way-to-be is untruth.5 Pure light is not the nature of Being nor is pure unconcealedness possible for man. Failure to remember this is the failure to realize that communication destroys itself in such flight because it no longer maintains the contingency of its task, i.e., the dis-closedness of being. We are reminded of the strong attraction this flight from darkness held for Plato. Light, truth and Being are all beyond the darkness and have nothing to do with it. In Book VII of the R~public, Socrates' explanation of the Allegory of the Cave to Glaucon points to a decided preference men have for the "lighted place". 5. The Origin Of The Work Of Art, pg. 42 5. Come then, I said, and join me in this further thought, and do not be surprised that those who attained to this height are not willing to occupy themselves with the affairs of men, but their souls ever feel the upward urge and yearning for that sojourn above. For this, I take it, is likely if in this point too the likeliness of our image holds. 6 Despite the attraction to pure truth, human communication is more complex than putting down one mode of communication and picking up another. Due to the fact that we are always on the way, the title of my thesis will have to be amended: OUT OF THE DARKNESS AND INTO THE LIGHT--AGAIN AND AGAIN. It must be this way because this is what it means to be human. This is the point made by Mephisto to Faust in pointing out that man, standing between God and the devil, needs both darkness and light: Er findet sich in einem ewigen Gl~t Uns hat er in die Finsternis gebracht, Und euch taugt einzig Tag und Nacht. 7 6. Republic z (517 c & d) It should be noted however, that while the philosopherking must be compelled to return to the cave for purely political reasons, once he has taken adequate view of the "brightest region of being" he has the full truth and his return to darkness adds nothing to the truth. 7. Faust, pg. 188 6. This thesis proposes to examine the grounds that give rise to communication, uncovering the structure of its inauthentic and authentic modes and paying close attention to tpeir interrelationship and to their relationship to language as "the house of Being": language that both covers and opens up man's rootedness in Being, transforming him as he moves along his way, taking up his "ownmost task" of becoming who he is. roots. He is the being who shows himself inn that reflects his forgetfulness or remembrance of his rootedness in being. Man comes into an already existent world and is addressedl through things in the world which are c