Chemical mutagenesis in relation to the concept of the gene

Zusammenfassung Die vorliegende Arbeit gibt einen Überblick über neuere Untersuchungen chemischer Mutationsauslösungen mit besonderer Betonung der Induktion von Chromosomenbrüchen in Pflanzen und Rückmutationen beiNeurospora. Die Arbeit zeigt, dass jedes Allel ein charakteristisches Mutationsverhalten zeigt, das durch die Reaktion auf physikalische und chemische Mutagene definiert wird. Diese Ergebnisse werden unter dem Aspekt diskutiert, dass ein Gen die Einheit der Funktion, Rekombination und Mutation darstellt.     

Change in sensitivity to lipopolysaccharide during the differentiation of human monocytes to macrophages in vitro

Mononuclear phagocytes in distinct differentiation stages and cultured under different conditions were tested for their sensitivity towards lipopolysaccharide (LPS), using procoagulant activity (PCA) expression and tumor necrosis factor (TNF) production as indices. The response of mature monocyte-derived macrophages differed from that of freshly isolated monocytes 1) by higher levels of constititive PCA, 2) by responding to approximately 1,000-fold lower concentrations of LPS with PCA and TNF production, and 3) by a faster rise in PCA and TNF production. Due to the high constitutive level of PCA expression, the PCA stimulation index for LPS was low in macrophages when compared with that in monocytes. Thus, during differentiation to macrophages, human monocytes acquire increased sensitivity to LPS (2 orders of magnitude more sensitive than a sensitive turbidimetricLimulus amoebocyte lysate assay). This exquisite sensitivity to LPS is expressed regardless of whether LPS is offered in the presence or absence of lipopolysaccharide binding protein-containing serum. This points to as yet uncharacterized pathways of high affinity interaction between LPS and macrophages.     

The possibility of centrifugal to the retina in the rat

Summary In rats, glutamic acid decarboxylase activity increased in the proximal portion of the optic nerve after its ligation, whereas the activities of choline acetyltransferase and tyrosine hydroxylase remained constant. Possible centrifugal neurons to the retina are GABAergic.     

A contribution to the problem of the haem-protein linkage in haemoglobin

Résumé L'histidine inhibe la combinaison de l'oxygène avec l'hémoglobine. L'analyse de la courbe, donnant la relation entre lat _u des courbes de dissociation d'oxygène et la concentration de l'histidine, donne pour résultat qu'une molécule de histidine déplace deux molécules d'oxygène. On peut conclure que les hèmes s'attachent à la partie protéinique de l'hémoglobine par un seul groupement d'imidazole.      

The possibility of centrifugal projections to the retina in the rat

In rats, glutamic acid decarboxylase activity increased in the proximal portion of the optic nerve after its ligation, whereas the activities of choline acetyltransferase and tyrosine hydroxylase remained constant. Possible centrifugal neurons to the retina are GABAergic.     

From proportion to balance: the background to symmetry in science

We call attention to the historical fact that the meaning of symmetry in antiquity—as it appears in Vitruvius’s De architectura—is entirely different from the modern concept. This leads us to the question, what is the evidence for the changes in the meaning of the term symmetry, and what were the different meanings attached to it? We show that the meaning of the term in an aesthetic sense gradually shifted in the context of architecture before the image of the balance was attached to the term in the middle of the 18th century and well before the first modern scientific usage by Legendre in 1794.     

Variation in the toxicity of various silicas in relation to the duration of presence in the body]

The toxic effect of two forms of sand on the lung was investigated by tracheal injection in Rats. After a latent period with low toxicity, more and more extensive pulmonary lesions, comparable to typical silicotic lesions, appear progressively. On the basis of some observations, the hypothesis is put forward that the impurities present in the dust have a retardative effect.     

Morphology of the intercapsular segment of the oviduct in the golden hamster with special reference to ovumtransit from ruptured follicles to the ampulla

Summary The intercapsular segment of the oviduct in the golden hamster is not a simple duct which has constant outer and inner diameters. After penetrating the bursa ovarica the ICS has a circular constriction and the corresponding oviductal lumen is narrowed.     

Development of behavioural tolerance to nicotine in the rat

Résumé On a donné de la nicotine à des rats une fois par jour, pendant 10 jours. L'activité des animaux a d'abord diminué, mais après quelques administrations de la drogue, on constata une accoutumance à ces effets. L'administration terminée, l'activité a augmenté.

---

---

This work was supported by a grant from the Tobacco Research Council.     

Liver catalysis in the association of estrogen to protein

Zusammenfassung Die Inkubation von 16-C¹⁴-Oestron und 4-C¹⁴-Oestradiol--acetat in Puffer (pH 7.4) bei Gegenwart von Rattenleber ergibt elektrophoretisch zwei deutliche radioaktive Bänder. Das erste Band entsteht im Albuminbereich und stimmt mit den früheren Beobachtungen vonSzego undRoberts ² überein. Das zweite, früher nicht beschriebene Band entsteht deutlich ausserhalb des Albuminbereiches. Beide Kurvengipfel werden mit wenig homogenisierter Rattenleber, die möglichst frei von Mikrosomen ist, gewonnen. Der zweite Gipfelpunkt wird in diesem Fall der obenauf schwimmenden Phase zugeschrieben.