The effect of clinorotation on vestibular compensation in upside-down swimming catfish.

Upside-down swimming catfish Synodontis nigriventris can keep upside-down swimming posture stably under pseudo-microgravity generated by clinostat. When the vestibular organ is unilaterally ablated, the operated S. nigriventris shows disturbed swimming postures under the clinorotation condition. However, about 1 month after the operation, unilateral vestibular organ-ablated S. nigriventris shows stable upside-down swimming posture under the condition (vestibular compensation). In contrast, a closely related upside-up swimming catfish Synodontis multipunctatus belonging to same Synodontis family can not keep stable swimming postures under the clinorotation conditions. In this study, we examined the effect of continuous clinorotation on vestibular compensation in intact and unilateral vestibular organ-ablated Synodontis nigriventris and Synodontis multipunctatus. After the exposure to continuous clinorotation, the postures of the catfish were observed under microgravity provided by parabolic flights of an aircraft. Unilateral vestibular organ-ablated S. nigriventris which had been exposed to continuous clinorotation showed stable swimming postures and did not show dorsal light reaction (DLR) under microgravity. This postural control pattern of the operated catfish was similar to that of intact catfish. Intact and unilateral vestibular organ-ablated S. multipunctatus showed DLR during microgravity. Our results confirmed that S. nigriventris has a novel balance sensation which is not affected by microgravity. DLR seems not to play an important role in postural control. It remains unclear that the continuous clinorotation effects on vestibular compensation because we could not keep used unilateral vestibular organ-ablated fish alive under continuous clinorotation for uninterrupted 25 days. This study suggests that space flight experiments are required to explore whether gravity information is essential for vestibular compensation.     

High transmittance of X-rays in the utricular otolith of upside-down swimming catfish, Synodontis nigriventris.

The upside-down swimming catfish (Synodontis nigriventris) has unique behavior, i.e., it frequently shows a stable upside-down posture during swimming and resting. To examine whether the unique postural control in S. nigriventris results from the characteristics of the vestibular organ, we observed the morphological aspects of the otolith and the orientation of sensory hair cells in the utricle. Soft X-ray densitometry analysis showed that the transmittance of soft X-rays in the otolith of S. nigriventris was higher than that in a closely related species (Synodontis multipunctatus) belonging to Synodontis family, goldfish (Carassius auratus) or miniature catfish (Corydoras paleatus) which shows upside-up swimming. The higher transmittance of soft X-rays suggests that the density of the otolith in S. nigriventris is lower than that in S. multipunctatus, C. auratus or C. paleatus. It is possible that the low density of the otolith may have a relation to the control of the unique upside-down posture of S. nigriventris. The hair cells in S. nigriventris were present at the ventral to ventro-lateral site of the utricular epithelium, forming a single hair cell layer as in the other 3 species of fish. The orientation of the sensory hair cells does not appear to cause the unique postural control.     

Comparative study of otolith organs between two species of upside-down swimming catfish Synodontis nigriventris showing converse swimming postures

To clarify whether the unique postural control of the upside‐down swimming catfish (Synodontis nigriventris, family Mochokidae) is related to the histological characteristics of the otolith organs, we performed light microscopic observation of the utricle, the saccule and the lagena. The histological aspects of the otolith organs were compared between S. nigriventris and Synodontis multipunctatus, which belong to the same genus. S. multipunctatus usually shows upside‐up swimming posture except for feeding behaviour near water surface. As controls, we additionally used a miniature catfish, Corydoras paleatus and goldfish, Carassius auratus, which shows upside‐up swimming posture. We concluded that the structural aspects of the otolith organs did not cause the unique postural control of S. nigriventris. Light microscopic observation clarified the following aspects: (1) The utricle of S. nigriventris was located at the anterior region of the otocyst and under the semicircular canals, and the saccule and the lagena were located at the posteroventral region of the otocyst like those of S. multipunctatus and the other two fishes. (2) The hair cells of the utricle were arranged on the horizontal plane of the fishes with a variation in cell size at the ventral and ventrolateral sites in S. nigriventris, S. multipunctatus and the other two fishes. (3) The hair cells of the saccule and lagena of S. nigriventris, S. multipunctatus and C. auratus presented perpendicular to the horizontal plane of the fish. (4) Region‐specific differences in the size and shape of the hair cells of S. nigriventris were observed along the three‐dimensional axes of the otolith organs like those of S. multipunctatus and the other two fishes. It is unlikely that the unique postural control of upside‐down catfish is related to the localization of the utricle, the saccule and the lagena and the distribution of the different types of hair cell of the otolith organs. Furthermore, the distribution of the hair cells suggests that the otolith organs in S. nigriventris can detect three‐dimensional postural changes like the organs of other fishes showing generally observed upside‐up swimming posture.     

Postural control under clinorotation in upside-down catfish, Synodontis nigriventris.

The upside-down catfish Synodontis nigriventris has a unique habit of swimming and resting upside-down in free water. This behavior leads to the assumption that the catfish has a specific gravity information processing system. We examined the postural control behaviors in the catfish under clinorotation which is usually used for producing pseudo-microgravity. Synodontis nigriventris kept its body posture at a stable area of the rotated flask in which the catfish was kept, when it was clinorotated at the rate of 60 rpm. In contrast to Synodontis nigriventris, a related species, Corydoras paleatus, did not show such steady postural control. When the flask was rotated at a lower rate of 30 rpm or a higher rate of 100 rpm, Synodontis nigriventris as well as Corydoras paleatus showed a considerable disturbed control of body posture. In this condition, they were frequently rotated with the flask. These findings suggest that Synodontis nigriventris has a high ability to keep upside-down posture and the gravity sensation in this catfish is likely to contribute to its different postural control from that of many other fishes.     

Correlation between body color and behavior in the upside-down catfish,Synodontis nigriventris

• 1.1. Unlike common fishes and as its Latin name implies, the upside-down catfish, Synodontis nigriventris, possesses dark ventral skin. Microscopic observation reveals that melanophores are present on both the ventral and the dorsal skin but differ in size and density of distribution.
• 2.2. The darkness of both sides of the fish changes in accordance with that of the background.
• 3.3. At night, the fish are very active and the body becomes pale. The change in color is more noticeable in the dorsal than the ventral skin.
• 4.4. When melatonin was added to the bathing water, the fish became pale and swam restlessly even when they were exposed to the black background.
• 5.5. It was found that the catfish preferred the black background to the white one.

     

Die Paarungsbalz des Schwarzhalstauchers

Zusammenfassung Die Paarungsbalz vonPodiceps nigricollis konnte eingehend beobachtet werden. Während der Aufforderungshaltung und zu Beginn der Einladehaltung schwimmt das hinter dem umher, dabei sich häufig putzend, bis es zur Kopulation aufspringt. Während dieser und beim darauffolgenden Lauf über den Rücken des ertönt das Paarungsduett. Zum Abschluß vollführen beide Partner eine Nachbalz.

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Summary The Pairing behaviour of the Black-necked Grebe is described. During the rearing posture and during the begin of the invitatory posture of the female the male swims behind her. Then he propels himself out of the water to his copulation posture, runs along the back of the female and springs near her neck into the water at the rim of the nest. Now the female raises and both partners show a fine post-courtship display. While the female bears the male at her back both sing their copulation-duet.

     

Retinofugal and retinopetal connections in the upside-down catfish (Synodontis nigriventris)

Summary The retinofugal and retinopetal connections in the upside-down catfish Synodontis nigriventris were studied by use of the horseradish-peroxidase (HRP) techniques, autoradiography, and degeneration-silver methods. An unusual retinal projection to the torus semicircularis as well as projections to the retina from three different sources in the brain are described. After intra-ocular injections of HRP, labeled cells were found in the optic tectum, the dorsomedial optic nucleus and one of the pretectal nuclei. These new findings support the basic hypothesis (i) that neuronal connections are more extensive in primitive brains, and (ii) that the evolutionary development of more complex brains involves the loss of some selected connections.     

Unique postural control of upside-down swimming catfish,Synodontis nigriventris,not affected by the change of gravity

In general, most fishes maintain a swimming posture with the dorsal side towards the water surface under normal gravity condition. In contrast to normal fishes, a catfish Synodontis nigriventris, shows a unique postural control. The catfish keeps its posture with the ventral side towards the water surface and the dorsal side towards water bottom under normal gravity. This evidence leads one to assume that the upside-down posture of the catfish is controlled by gravity sensation in a manner different from that of other fishes. However, it has remained unclear to date whether the gravity sensation contributes to the unique postural control of this catfish. We examined its postural control in intact and labyrinth-removed catfish using a clinostat which generates a specific gravity environment (pseudo-microgravity) on earth. In addition, we examined its postural control under microgravity during parabolic flights.     

Somatic embryogenesis and plant regeneration from protoplasts of Cichorium intybus L. x Cichorium endivia L.

Somatic embryos and adult plants were regenerated from mesophyll protoplasts of a clone of chicory 474 (Cichorium intybus L. x Cichorium endivia L.). Embryos were obtained in three different ways:

Subcellular localization of luteolin glucuronides and related enzymes in rye mesophyll

Vacuoles were isolated by osmotic rupture of mesophyll protoplasts from the primary leaves of 4-d- and 7-d-old plants of rye (Secale cereale L.). Their content of two flavones, luteolin 7-O-[-d-glucuronosyl-(12)-d-glucuronide] (R₂) and luteolin 7-O-[-d-glucuronosy 1 (12) -d-glucuronide]-4-O--d-glucuronide (R₁), as well as that of three specific flavone-glucuronosyltransferases involved in their biosynthesis and of a specific -glucuronidase was determined in comparison to the parent protoplasts. The two flavonoids were found to be entirely located in the vacuolar fraction, together with 70% of the activity of UDP-glucuronate: luteolin 7-O-diglucuronide-4-O-glucuronosyl-transferase (LDT; EC 2.4.1.), the third enzyme of the sequence of three transferases in the anabolic pathway. The activities of the first and second anabolic enzymes, UDP-glucuronate: luteolin 7-O-glucuronosyltransferase (LGT; EC 2.4.1.) and UDP-glucuronate: luteolin 7-O-glucuronide-glucuronosyltransferase (LMT; EC 2.4.1.) could not be found in the vacuolar fraction in appreciable amounts. The specific -glucuronidase (EC 3.2.1.), catalyzing the deglucuronidation of luteolin triglucuronide to luteolin diglucuronide, was present with 90% of its activity in the digestion medium after isolation of mesophyll protoplasts, indicating an apoplastic localization of this enzyme. The data presented indicate a directed anabolic and subsequent catabolic pathway for the luteolin glucuronides in the mesophyll cells of rye primary leaves. This includes two cytosolic and a last vacuolar step of glucuronidation of luteolin, and the vacuolar storage of the luteolin triglucuronide. We propose the transport of the latter into the cell wall, after which the triglucuronide is deglucuronidated, this being the first step for further turnover.Dedicated to Professor Ludwig Bergmann, Botanisches Institut der Universität zu Köln, on the occasion of his 65th birthday     

“Differentiation Induction” culture of human leukemic myeloid cells stimulates high production of macrophage differentiation inducing factor

A suitable procedure for the production of human monokines was defined as differentiation-induction culture. Human monocytic leukemia THP-1 cells were well-differentiated from nonfunctional promonocytes into macrophage-like cells by the induction with a combination of mezerein, retinoic acid, and aMycoplasma fermentans extract. The differentiated THP-1 cells secreted a high amount of macrophage differentiation-inducing factor (DIF) activity and concomitantly produced other known monokines, such as tumor necrosis factor- (TNF-), interleukin-1 (IL-1) and interleukin-1 (IL-1), into the medium. These results suggest that other novel human monokines may also be found in the conditioned medium of THP-1 cells induced by the differentiation-induction culture conditions defined in this study. Macrophage DIF was purified to homogeneity and NH₂-terminal amino acid sequence analysis revealed that macrophage DIF is very similar or identical to human leukemia inhibitory factor (LIF). The cDNA encoding human LIF was isolated using the polymerase chain reaction, and a clone producing 3.7 g/10⁶ cells day recombinant LIF was selected from Chinese hamster ovary (CHO) cells which were transfected with the LIF cDNA. The recombinant LIF production in CHO cells was quantified using MTT reduction assay with M1 cells.     

Brain function in antarctic fish: Activity of central vestibular neurons in relation to head rotation and eye movement

Summary Recordings were made from central vestibular neurons responding to horizontal head rotation in antarctic fish,Pagothenia borchgrevinki, at a temperature close to 0 °C. The spontaneous activity of these units varied between 0 and 56 Imp/s with a mean value of 20. Almost all units responded to horizontal rotation with a maximum firing rate that was approximately in phase with head velocity, either towards the recording side (type I units) or away from the recording side (type II), with no alteration of firing pattern during saccadic eye movements. The mean gain of these units was 2.6 Imp/s//s at 0.35 Hz which is higher than that reported for central vestibular neurons in other fish.