Feedback inhibition of homoserine dehydrogenase and threonine deaminase in the genusBifidobacterium

Feedback inhibition of crude and purified extracts of homoserine dehydrogenase and threonine deaminase activities in the genusBifidobacterium was studied. Homoserine dehydrogenase was partially or completely inhibited byl-threonine, and a marked inhibitory effect byl-isoleucine on threonine deaminase was observed. In the speciesBifidobacterium cuniculi high levels ofl-valine reversed the inhibitory effect ofl-isoleucine. The -aminobutyric acid-resistant mutant Ru 326/106 of the speciesB. ruminale, overproducer ofl-isoleucine, had a derepressed homoserine dehydrogenase and a lesser feedback inhibition byl-threonine. Homoserine dehydrogenase appeared to be in bifids specifically NAD dependent. The regulatory mechanisms of aspartate family amino acid biosynthesis in bifidobacteria was discussed.     

Deoxyribonucleic acid homology among the species of the genus Bifidobacterium isolated from animals

Summary Representatives of the species of the genus Bifidobacterium isolated from bovine rumen, intestinal content of honey bees and pig feces were studied for their deoxyribonucleic acid similarities with DNA-DNA filter hybridization-competition experiments. The species were: B. asteroides, B. indicum and B. coryneforme from honey bees; B. ruminale and B. globosum from rumen; B. suis from pig feces; Mitsuoka's species B. thermophilum and B. pseudolongum. Strains of B. bifidum, B. infantis, B. longum and B. breve from human sources were included in some comparative experiments. The group of bacteria investigated is largely heterogeneous: virtually no homology exists among the species from rumen and pig feces; the species or types from bees, although unrelated with rumen and pig types, share with these a significant portion of the genome; the competitor DNA's from human strains did not at all react with any of the homologous systems. The annealing reaction was carried out under stringent conditions to ensure against mismatching of nucleotide sequences (70°C in Denhardt's reactive mixture). The separation within the genus Bifidobacterium of several specific entities is fully substantiated.This investigation was supported by a research grant of C. N. R. (Consiglio Nazionale delle Ricerche, Roma).     

Purification and properties of two fructose-6-phosphate phosphoketolases in Bifidobacterium

Fructose-6-phosphate phosphoketolase was purified from type strains of two species of the genus Bifidobacterium: B. globosum and B. dentium. The first species has a preferred animal habitat, like feces of animals and rumen of cattle; the latter is harboured in human habitats, like feces and dental caries of man. Two electrophoretic types of phosphoketolase (F6PPK) were previously distinguished and called animal and human type according to the habitat of the bifid organism. The purified preparations of these two phosphoketolases displayed very different optimum pH range, metal activator and molecular weight; outstanding difference was found in the substrate specificity: the enzyme from B. globosum was able to split xylulose-5-P as well as fructose-6-P, whereas the phosphoketolase from B. dentium appeared to be specific for fructose-6-P.     

Expression of the β-subunit of β-conglycinin in seeds of transgenic plants

Soybean (Glycine max (L.) Merr.) seeds contain the storage protein -conglycinin, encoded by a multigene family. -Conglycinin consists of three subunits; , , and . A genomic clone for a -subunit of -conglycinin has been characterized by restriction-enzyme mapping and hybrid selected in-vitro translation followed by immunoprecipitation. In order to determine the developmental regulation of this -subunit gene, its expression was studied in seeds of transgenic petunia (Petunia hybrida) and tobacco (Nicotiana tabacum L.) plants. The -subunit expressed in seeds of petunia and tobacco was recognized by anti--conglycinin serum at a relative molecular mass of 53 000, equivalent to that of the native protein. Separation of the petunia-seed proteins by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed that multiple isoelectric forms of the -subunit were produced. There was approximately a twofold variation in the accumulation of the -subunit protein in the mature seeds of transgenic petunia plants, each containing a single -subunit gene. However, the level of protein accumulation in mature seeds and the amount of -subunit mRNA in developing seeds was not correlated. Accumulation of the -subunit protein in transgenic seeds was less than the -subunit protein that accumulated in transgenic petunia seeds containing a single -subunit gene and less than the amount of the -subunit in mature soybean seeds which contain 8–13 -subunit genes. In transgenic tobacco plants, the accumulation of the -subunit protein in seeds was generally well correlated with the number of genes that were incorporated in the different transformants.Abbreviations kb kilobase - kDa kilodalton - M_r relative molecular mass - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis     

Genetic organization of the E. coli chromosome around the structural gene for initiation factor IF3 (infC).

Summary A set of transducing phages carrying varying lengths of the E. coli chromosome around the structural gene for initiation factor IF3 (infC) was derived from p2 which is known to cary, besides infC, the structural genes for the subunit of phenylalanyl-tRNA synthetase (pheS), the subunit of phenylalanyl-tRNA synthetase (phetT) and the structural gene for threonyl-tRNA synthetase (thrS). The E. coli coding content of these derived phages was analysed by genetic complementation of a set of mutants and by SDS-polyacrylamide gel analysis of the proteins synthesized in UV irradiated cells infected with these phages. The segregation pattern of the different genes among these derived phages indicates that the order of the genes is pheT-pheS-P12-(infC, thrS) where infC is probably between P12 and thrS. P12 is the structural gene of a 12,000 molecular weight unidentified protein.Abbreviations PRS (EC 6.1.1.20) phenylalanyl-tRNA synthetase - TRS (EC 6.1.1.3) threonyl-tRNA synthetase - IF3 Initiation factor IF3 - SDS Sodium dodecyl sulfate - PP^R pyrophosphate resistant - PP^S pyrophosphate sensitive     

Histochemical demonstration of the intestinal hetero-β-galactosidase (glucosidase)

Summary The histochemical demonstration of hetero--galactosidase (glucosidase) has been attempted in sections and zymograms of rabbit, monkey and human intestine and of rat kidney.The leakage of this enzyme from unfixed sections was prevented by the use of cold microtome sections adherent to semipermeable membranes. Methods with -D-glucosides and galactosides of 6-Br-2-naphthol (postincubation azocoupling with Fast Blue B as well as simultaneous azocoupling with hexazonium-p-rosaniline), of -naphthol (simultaneous azocoupling with hexazonium-p-rosaniline) and of 4-Cl-5-Br-3-indolyl (with ferricyanide, phenazonium methosulfate or nitro BT and without any oxidation agent) were used an evaluated concerning the specificity, localization ability and inhibition of enzyme activity. Pretreatment of sections with distilled water or saline and inhibition by p-Cl-mercuribenzoate, glucono- and galactono-lactones were used for the characterization of the demonstrated enzyme activity.6-Br-2-naphthyl--D-glucoside is the most specific substrate for hetero--galactosidase. It is not split by lactase and acid -galactosidase. Only lysosomal -glucosidase can interfere. Because the latter enzyme is membrane-bound the difference in color intensity between untreated and prewashed sections are due to hetero--galactosidase. Only localization on the cellular (not intracellular) level can be achieved, however.The simultaneous azocoupling method with -naphthyl--D-glucoside and hexazonium-p-rosaniline enables a very good localization of hetero--galactosidase in the rabbit intestine. Due to a great inhibition exerted by hexazonium-p-rosaniline on the enzyme activity the method is unsuitable for the detection of hetero--galactosidase in zymograms and in the human intestine. Interference of lactase (or lactase-phlorizine hydrolase complex) is to be considered. The lysosomal -glucosidase does not seem to interfere.Indigogenic methods are not sensitive either. With ferricyanide as an oxidation agent it was not possible to detect the activity of hetero--galactosidase in zymograms and in sections. This is possibly due to overoxidation of indigo. The same holds true for phenazonium methosulfate used for the processing of zymograms. However, it was possible to reveal the activity of hetero--galactosidase in sections of the rabbit and monkey intestine with phenazonium methosulfate as oxidation agent. Nitro BT enhanced the coloration both in zymograms and in sections. In the latter case diffusion artifacts cannot be prevented, however. The interference of lactase, lysosomal -galactosidase and possibly of lysosomal -glucosidase (depending on the glycoside used) is always to be considered.Hetero--galactosidase was localized in the cytoplasm (particularly in the supranuclear region) of differentiated enterocytes covering the villi of the rabbit (the highest activity), monkey and human (the lowest activity) intestine. In crypt enterocytes and in cells of Brunner's glands the activity was lower. The occurrence of a low activity of hetero--galactosidase in the brush border of enterocytes of the rabbit intestine was also demonstrated.A proximodistal gradient was observed in the rabbit and monkey intestine, the upper jejunum displaying the highest activity.In jejunal biopsies of patients with celiac sprue (in the acute stage of the disease) the activity of hetero--galactosidase was lowered. No changes of activity were observed in jejunal biopsies of patients with isolated deficiencies of lactase or sucrase.In the rat kidney the enzyme was demonstrated particularly in the cytoplasm of cells of proximal convoluted tubules.     

Co-utilization of Bacillus subtilis and Flutolanil in controlling damping-off of tomato caused by Rhizoctonia solani

Damping-off of tomato caused by Rhizoctonia solani was controlled in a pot test using the biological agent, Bacillus subtilis RB14-C, and the chemical pesticide, Flutolanil. The co-utilization of B. subtilis RB14-C, and Flutolanil decreased the amount of Flutolanil used from 375 g/pot when Flutolanil was used alone to 94 g/pot, while exerting the same effect of reducing disease occurrence.     

Chemoenzymatic galactosialylation with integrated cofactor regeneration

As a precursor for the chemical synthesis of sialylated oligosaccharides, the trisaccharide glycoside Neu5Ac (2-8)Gal(1-4)GlcNAc(1-O)-pent-4-ene was synthesized starting from GlcNAc(1-O)-pent-4-ene, UDP-glucose andN-acetylneuraminic acid in a one pot reaction employing galactosyltransferase and (2-6)sialyl-transferase in a complete cofactor regeneration system.Abbreviations Neu5Ac N-acetylneuraminic acid - CMP-Neu5Ac cytidine 5-monophosphosialate - CMP cytidine 5-monophosphate - CDP cytidine 5-diphosphate - CTP cytidine 5-triphosphate - Gal galactose - GlcNAc N-acetylglucosamine - UDP uridine 5-diphosphate - UDP-Glc uridine-5-diphosphoglucose - UDP-Gal uridine-5-diphosphogalactose - PEP phosphoenolpyruvate     

Preliminary quantification of immunological relationships among the transaldolases of the genus Bifidobacterium

The immunological relatedness among the transaldolases (dihydroxyacetone transferase, E.C. 2.2.1.2) of twenty species of the genus Bifidobacterium has been tested by the microcomplement fixation method, using B. thermophilum (B. ruminale) RU326 (=ATCC 25866), B. cuniculi RA93(=ATCC 27916) and B. minimum (DNA homology group) F392 (=ATCC 27538) as references. Based on the serological relationships of the transaldolases, expressed either as indices of dissimilarity or as immunological distances, the twenty species of the genus Bifidobacterium were arranged into clusters. These clusters generally coincided with the immunological groups obtained previously by the immunodiffusion method (Sgorbati and Scardovi, 1979).     

Visual edge fixation and negative phototaxis in the mealworm beetle Tenebrio molitor

The visual fixation response of the mealworm beetle Tenebrio molitor, elicited by black stripes upon a bright background is studied in an arena and by means of the Y-maze technique. In the arena the distribution n() of the beetle's angular position is measured at different distances from the centre, which is also the starting point. If the black stripe is narrow, the maximum of n() coincides with the centre of the stripe (centre-fixation Figure 1a). If one half of the panorama is black, the distribution n() has two maxima, which are near the borders between the black and white regions (edge-fixation Figure 1b). In the Y-maze experiments the beetle is tethered, but its head is free to move. The black stripes elicit turning tendencies F(), the strength of which depends upon the angular distance between the centre of the stripe and the animal's body axis. If the black stripe is narrow, the stable zero crossing of F() lies at =0, in agreement with the centre fixation in the arena (Fig. 3). If the stripe is 180° wide, two stable zero crossings are obtained near the border lines between the black and white regions, provided that the panorama is rotated around the animal with an angular velocity w larger than about 0.08°/s (Fig. 4). Below this value of w only one stable zero crossing at =0 exists (Fig. 6). Thus the tethered beetle's response underlies a transition between centre resp. edge fixation at a critical angular velocity of the drum. Some implications of this surprising phenomenon with respect to the mechanism of fixation and negative phototaxis are discussed but at present it is considered primarily a challenge for further investigation.Supported in part by Deutsche Forschungsgemeinschaft     

Nucleotide sequence of cytoplasmic 5S ribosomal RNA fromEuglena gracilis

Summary The nucleotide sequence of cytoplasmic 5S ribosomal RNA fromEuglena gracilis has been determined to be: G- _A ^C -G-U-A-C-G-G-C-C-A-U-A-C-U-A-C-C-G-G-G-A-A-U-A-C-A-C-C-U-G-A-A-C-C-C-G--U-C-G-A-U-U-U-C-A-G-A-A-G-U-U-A-A-G-C-C-G-G-G-U-U-A-G-G-C-C-C-A-G-U-U-A-G-U-A-C-U-G-A-G-U-G-G-G-C-G-A-C-C-A-C-U-U-G-G-G-A-A-C-A-C-U-G-G-G-U-G-C-U-G-U-A-C-G-C-U-Up. This RNA is 119 nucleotides long and the sequence of a probable tRNA-binding site is GAUU (position 41–44 from the 5-terminus), which is the same as that of a trypanosoma species,Crithidia fasci-culata. TheEuglena 5S rRNA has a pseudouridine residue at position 38 and 3-terminus is phosphorylated. The 5S rRNA sequence ofEuglena resembles those of several other protozoa and higher animals rather than plants.On leave from Department of Zoology, Hiroshima University, Hiroshima, Japan     

Die exoepithelialen Schleimdrüsenzellen von Arion empiricorum (Fér.)

Zusammenfassung Im Oberflächenepithel der Wegschnecke Arion empiricorum (Fér.) existieren drei Arten von exoepithelialen Schleimdrüsenzellen. Sie können auf Grund der Ultrastruktur, aber auch durch Heterochromasie bei Toluidinblaufärbung (bei verschiedenen pH-Werten), unterschieden werden. Der Typ der ventralen Sohlendrüse kommt in der Kriechsohle, der Schwanzdrüse, den Tentakeln, der Kopfhaut und in der vom Pneumostom ventrad ziehenden Flimmerrinne vor, der Typ der lateralen Sohlendrüse seitlich unter dem Sulcus lateralis. Die Manteldrüsen sind im übrigen Epithel zu finden.Die ventralen Sohlendrüsen sind durch ein eigenartig strukturiertes Ergastoplasma ausgezeichnet, die lateralen Sohlendrüsen besitzen ein Ergastoplasma, das auf Proteinbildung hinweist und die Manteldrüsen besitzen als Charakteristikum riesige Golgi-Vakuolen.

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Summary In the surface epithelium of the slug, Arion empiricorum (Fér.), there exist three types of exoepithelian slime-gland-cells. They can be distinguished on account of their ultrastructure as well as by the fact that they show heterochromatism at different pH-values after toluidine-blue-staining. The type of the ventrale Sohlendrüse occurs in the under surface of the foot, in the large slime-gland at the tail, in the tentacles, in the epidermis of the head and in the ciliated groove underneath the pneumostome, the type of the laterale Sohlendrüse on the sides underneath the sulcus lateralis. The Manteldrüsen are to be found in the other places of the epithelium.The ventrale Sohlendrüsen are characterized by their specific ultrastructure of the ergastoplasm, the laterale Sohlendrüsen by a type of ergastoplasm, which shows signs of protein-production, the Manteldrüsen however by containing huge Golgi-vacuoles.

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Herrn Professor L. Stockinger danke ich für Kritik und Ratschläge.     

Morphology of some species of the genus Aulodrilus Bretscher

The external and internal morphology of Aulodrilus limnobius Bretscher, 1899, Aulodrilus pluriseta (Piguet, 1906) and Aulodrilus japonicus Yamaguchi, 1953, and morphology of the setal apparatus of Aulodrilus pigueti were studied on new material from Russia and compared with various literature data. Besides the peculiar wings on bifid setae, dominance of asexual reproduction is regarded as a primary synapomorphy of the genus and is accompanied by an anterior shift of the whole reproductive system and a tendency to doubling the gonads. Naidid-like cocoons, with a single egg, are another element of this reproductive mode. Similar characters seem to have arisen independently in several groups of Oligochaeta.     

Orthopaedic implant related metal toxicity in terms of human lymphocyte reactivity to metal‐protein complexes produced from cobalt‐base and titanium‐base implant alloy degradation

Metal toxicity from sources such as orthopaedic implants was investigated in terms of immune system hyper-reactivity to metal implant alloy degradation products. Lymphocyte response to serum protein complexed with metal from implant alloy degradation was investigated in this in vitro study using primary human lymphocytes from healthy volunteers (n = 10). Cobalt chromium molybdenum alloy (CoCrMo, ASTM F75) and titanium alloy (Ti6Al4V, ASTM F136) beads (70 m) were incubated in agitated human serum at 37 degrees Celsius to simulate naturally occurring metal implant alloy degradation processes. Particulate free serum samples, which were incubated with metal, were then separated into molecular weight based fractions. The amounts of soluble Cr and Ti within each serum fraction were measured and correlated with lymphocyte proliferation response to the individual serum fractions. Lymphocytes from each subject were cultured with 11 autologous molecular weight based serum fractions either with or without added metal. Two molecular weight ranges of human serum proteins were associated with the binding of Cr and Ti from CoCrMo and Ti implant alloy degradation (at < 30 and 180–330 kDa). High molecular weight serum proteins ( 180 kDa) demonstrated greater lymphocyte reactivity when complexed with metal released from CoCrMo alloy and Ti alloy than with low (5–30 kDa) and midrange (30–77 kDa) serum proteins. When the amount of lymphocyte stimulation was normalized to both the moles of metal and the moles of protein within each fraction (MetalProtein Complex Reactivity Index, MPCRI), Cr from CoCrMo alloy degradation demonstrated approximately 10 fold greater reactivity than Ti in the higher molecular weight serum proteins ( 180–250 kDa). This in vitro study demonstrated a lymphocyte proliferative response to both CoCrMo and Ti alloy metalloprotein degradation products. This response was greatest when the metals were complexed with high molecular weight proteins, and with metalprotein complexes formed from CoCrMo alloy degradation.     

Temperature dependencies and apparent activation energies of stomatal opening and closing

Summary Stomatal opening movements in response to illumination, and stomatal closure following darkening were studied in leaf sections of Zea mays, using air-flow porometers. Stomatal opening is characterized by a phase of linear increase of air flow through the leaf (slope = opening velocity); stomatal closure follows a relaxation curve from which a time constant (closing coefficient) can be derived.Apparent energies of activation, , were computed for the opening velocity and for the closing coefficient from stomatal movements recorded at tissue temperatures between 5° and 50°. It was assumed that the closing coefficient can be used as a measure of the closing force, and that the opening force has to exceed the closing force in order to bring about stomatal opening. is about 7 kcal mole^-1 for the closing coefficient and between 12 and 18 kcal mole^-1 for the opening force. Thus, during stomatal opening, metabolism must provide energy to build up a pressure difference between guard cells and the surrounding tissue.The process controlling the velocity of closure is essentially a passive loss of water (and solutes?) from the guard cells. The of 7 kcal mole^-1 found for the closing coefficient is, however, higher than that for the viscosity of water or for the coefficient of self diffusion of water. It is, therefore, concluded either that water interacts with the cell structures which it has to permeate during stomatal closure, or that the rate of salt loss from guard cells controls the velocity of stomatal closure.The closing force decreases when leaf temperature rises above 35° or falls below 15°. Therefore, stomata of maize open relatively faster and wider above 35° and below 15°, and the 's of the opening velocity appear to be very large above 35° (up to 50 kcal mole^-1) while they have a negative sign below 15°.Research supported by the U.SS. Atomic Energy Commission under contract AT (11-1) 1338. I thank Miss Freia Schulz-Baldes for interested technical assistance.     

Production of tyrosine and other aromatic compounds from phenylalanine by rumen microorganisms

Summary Rumen contents from three fistulated Japanese native goats fed Lucerne hay cubes (Medicago sativa) and concentrate mixture were collected to prepare the suspensions of mixed rumen bacteria (B), mixed protozoa (P) and a combination of the two (BP). Microbial suspensions were anaerobically incubated at 39°C for 12h with or without 1 MM ofl-phenylalanine (Phe). Phe, tyrosine (Tyr) and other related compounds in both supernatant and microbial hydrolysates of the incubations were analyzed by HPLC. Tyr can be produced from Phe not only by rumen bacteria but also by rumen protozoa. The production of Tyr during 12h incubation in B (183.6 mol/g MN) was 4.3 times higher than that in P. One of the intermediate products between Phe and Tyr seems to bep-hydroxyphenylacetic acid. The rate of the net degradation of Phe incubation in B (76.O mol/g MN/h) was 2.4 times higher than in P. In the case of all rumen microorganisms, degraded Phe was mainly (>53%) converted into phenylacetic acid. The production of benzoic acid was higher in P than in B suspensions. Small amount of phenylpyruvic acid was produced from Phe by both rumen bacteria and protozoa, but phenylpropionic acid and phenyllactic acid were produced only by rumen bacteria.     

Analysis of genomic and expressed major histocompatibility class Ia and class II genes in a hexaploid Lake Tana African ‘large’ barb individual (<Emphasis Type="Italic">Barbus intermedius</Emphasis>)

Expression of too many co-dominant major histocompatibility complex (MHC) alleles is thought to be detrimental to proper functioning of the immune system. Polyploidy of the genome will increase the number of expressed MHC genes unless they are prone to a silencing mechanism. In polyploid Xenopus species, the number of MHC class I and II genes has been physically reduced, as it does not increase with higher ploidy genomes. In the zebrafish some class IIB loci have been silenced, as only two genomically bona fide loci, DAA/DAB and DEA/DEB, have been described. Earlier studies indicated a reduction in the number of genomic and expressed class II MHC genes in a hexaploid African large barb. This prompted us to study the number of MHC genes present in the genome of an African large barb individual (Barbus intermedius) in relation to those expressed, adopting the following strategy. Full-length cDNA sequences were generated from mRNA and compared with partial genomic class Ia and II sequences generated by PCR using the same primer set. In addition, we performed Southern hybridizations to obtain a verification of the number of class I and IIB genes. Our study revealed three ₂-microglobulin, five class Ia, four class IIA, and four class IIB genes at the genomic level, which were shown to be expressed in the hexaploid barb individual. The class Ia and class II data indicate that the ploidy status does not correlate with the presence and expression of these MHC genes.     

Über die angebliche Acidophilie der Belegzellen

Zusammenfassung Aus der Bestimmung der Kristallponceau-Extinktion sowie aus den Ergebnissen der Färbung im Azur A-Eosingemisch bei variiertem pH läßt sich ableiten, daß sich die Belegzellen der Magenschleimheit nicht acidophil verhalten. Ihre gegenüber den Hauptzellen differente Darstellbarkeit fehlt nach Ribonucleasebehandlung. Der Färbemechnismus wird formelmäßig interpretiert.

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Summary Measuring results of the crystal ponceau extinction and staining results with an azur A-eosin mixture (of varying pH) indicate, that the parietal cells of the gastric mucosa are not acidophil cells. After treatment with ribonuclease their staining pattern does not differ any more from that of the chief cells. The staining mechanism is explained in detail.

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Herrn Prof. Dr. F. Timm zum 70. Geburtstag.     

Obstructed Bifid Uretereric System Causing Unilateral Hydronephrosis

Bifid ureters are a common malformation of the urinary system. In clinical practice, hydronephrosis resulting from obstruction of such a system is rare. The authors present a case involving an 88-year-old man admitted to the hospital with symptoms of renal failure, where bifid ureters were found incidentally in a hydronephrotic kidney during an emergency nephrostomy. This had been missed on a previous CT scan, resulting in a unique therapeutic dilemma.Key words: Bifid ureters, Hydronephrosis, NephrostomyIn 1948, Nordmark described bifid ureters, along with bifid renal pelves, as the most common malformation of the urinary system. Later studies confirmed this, with duplicated ureters being found in 1 in 125 patients (0.8%) in whom postmortem examinations were carried out.^1,2 Often, these remain asymptomatic, and as a result, undiagnosed. In symptomatic patients, bifid ureteric systems are often found to be dilated as a consequence of blind-ending branches. Such cases have frequently been described in medical literature; however, the finding of hydronephrosis resulting from tumor obstructing the bifid ureter is relatively rare.We present a case report of hydronephrosis due to back pressure from obstruction of the ureteric orifice. The obstruction resulted in dilatation of both the moieties of the bifid ureters, causing both a diagnostic and treatment dilemma.     

Effect of desiccation on the light reactions of Carpophilus dimidiatus and Tribolium castaneum

The effect of desiccation on the light reactions of Carpophilus dimidiatus and Tribolium castaneum was studied. The results indicated that in C. dimidiatus the light reactions of normal adults of either sex were unaffected by humidity conditions. After desiccation, light responses were found to vary according to humidity conditions and also with respect to the sex of adults examined. In T. castaneum normal adults showed different light reactions according to the humidity test conditions. However at one condition only, i.e. high humidity, the sexes responded differently. After desiccation light responses were still found to vary according to humidity but in both high and low humidities the response varied according to sex.

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Résumé On a étudié l'action de la dessiccation sur les réactions à la lumière de Carpophilus dimidiatus et Tribolium castaneum. Les résultats indiquent que les réactions à la lumière des adultes normaux de C. dimidiatus des deux sexes sont indépendantes des conditions d'humidité. Après dessiccation, les réponses à la lumière ont varié suivant les conditions d'humidité et aussi selon le sexe des adultes examinés. Chez Tribolium castaneum, les adultes normaux ont manifesté des réactions différentes à la lumière en fonction des conditions d'humidité. Cependant dans une condition unique, c'est à dire une humidité élevée, les sexes ont répondu différemment. Après dessiccation, les réactions à la lumière ont toujours été trouvées variables selon l'humidité, mais pour les deux humidités élevée et basse la réponse a varié suivant le sexe de l'adulte.