A new paradigm for operant conditioning of Drosophila melanogaster

A freely walking single fly (Drosophila melanogaster) can be conditioned to avoid one side of a small test chamber if the chamber is heated whenever the fly enters this side. In a subsequent memory test without heat it keeps avoiding the heat-associated side. The memory mutants dunce ¹ and rutabaga ¹ successfully avoid the heated side but show no avoidance in the memory test. Wildtype flies can be trained to successively avoid alternating sides in a reversal conditioning experiment. Every single fly shows strong avoidance and a positive memory score. The new conditioning apparatus has several advantages: (1) Statistically significant learning scores can be obtained for individual flies. (2) Learning scores are obtained fully automatically without interference of the experimenter. (3) The procedure is fast, robust and requires little handling. Therefore the apparatus is suitable for largescale mutant screening. (4) Animals are not attached to a hook and thus can easily be used for breeding.Abbreviations dnc dunce gene - PI performance Index - rut rutabaga gene - S.E.M. standard error of mean     

Discovery of a normal hermaphroditic chondrichthyan species: Apristurus longicephalus

Examination of the internal genital apparatus of Apristurus longicephalus , a small, deep‐water bottom‐dwelling catshark (Scyliorhinidae) from the western Pacific and Indian Oceans has revealed that it is a hermaphroditic species. It possesses both the developed genital apparatus of one sex and the undeveloped genital apparatus of the opposite sex in the same individual. Apristurus longicephalus is the first case of normal hermaphroditism to be recorded in cartilaginous fishes and this has been further classified as rudimentary hermaphroditism.     

Flagellar basal apparatus and its utility in phylogenetic analyses of the porifera

A broadly based comparative study was initiated to assess components of the flagellar basal apparatus as a character set in phylogenetic analyses of poriferans. The flagellated (monociliated) epidermal cells of sponge larvae were selected for study. Taken together, they create a field of locomotory cells analogous to a multiciliated surface. Larvae of six species in four orders of the Demospongiae were examined by transmission electron microscopy. Results are compared with findings taken from the literature on larvae of five additional species of demosponges and four species of calcareans. Data were assembled on six components of the basal apparatus: (1) basal body, (2) basal foot, (3) accessory centriole, (4) transverse cytoskeletal system, (5) longitudinal cytoskeletal system, and (6) association with Golgi body. Where evidence permits assessment, all have Type II basal bodies. Basal feet are diverse and are subdivided into three categories based on structural complexity. The most anatomically intricate (Type III) is found only in larvae of Mycale spp. Accessory centrioles are present or absent depending on the species, but their occurrence is without overall taxonomic pattern. When present, accessory centrioles are oriented perpendicularly to the long axis of the basal body, but as ascertained from relationship to the anterior-posterior axis of the larvae they are without consistent orientation with regard to the plane of effective beat of the flagellum. Transverse and longitudinal cytoskeletal systems are also diverse among larvae. The existence of cross-striated rootlets is convincingly established only in larvae of calcareans, and such rootlets are present in larvae of all four calcareans studied to date. Three apparently new rootlet structures are described: lateral arms of the transverse cytoskeletal system from larvae of Aplysilla sp. and Haliclona tubifera; laminar sheets of the longitudinal system from larvae of Aplysilla sp. and M. cecilia; and paraxial rootlet in larvae of H. tubifera. A robust similarity in structure of the basal appartus is observed among the three species of halichondrids reported here for the first time. In comparison with the flagellar basal apparatus found in adults, those of larvae are more complex and more diverse. Review of studies on adult sponges that include information on the basal apparatus reveals the absence of a longitudinal rootlet system in all cases. Additionally, there exists a high degree of concordance between properties of the basal apparatus in the one sclerosponge and the one hexactinellid studied to date. These basal apparatus are also the simplest in construction of those found in sponges. Conversely, the basal apparatus of demosponges are varied. Although consistent presentation of the basal apparatus is evident in certain taxa, any discernable systematic pattern in their overall configuration remains obscure. Finally, we conclude that the flagellar basal apparatus of sponges is more similar to that found in choanoflagellates than it is to that observed in eumetazoans. © 1995 Wiley-Liss, Inc.     

The epibranchial organ,its innervation and its probable functioning in Heterotis niloticus (Pisces,teleostei, osteoglossidae)

Synopsis The high level of encephalization in Heterotis niloticus is due, in part, to a voluminous lobus vagalis, which has the form of a cauliflower and receives the fibers of a strong branch of the 10^th (vagal) nerve. This vagal branch comes from a special branchial apparatus, the epibranchial organ, considered to be an air-breathing organ by some, and a microphagous apparatus by others. This organ has a spiral, snail-like form and its lumen is a blind-alley. Its study in a juvenile fish 10 cm SL shows that it has two canals: a peripheric one for water entrance and a central one for food exit. The epithelium between these two canals contains numerous gustatory buds, the innervation of which constitutes the branch of the vagal nerve. This epithelium is also very rich in mucous cells, which probably correspond to a muco-microphagous feeding apparatus. The exit canal, which receives the mucous string enriched with food particles, enters directly into the oesophagus. Striated muscles, attaching along the spiral tours of the epibranchial organ, probably serve as the motor that pumps water in and out and supplies the classical ciliary apparatus of the mucophagous feeding organs.     

狭基巢蕨叶表皮的结构和气孔器发育的观察

狭基巢蕨Ｎｅｏｔｏｐｔｅｒｉｓａｎｔｒｏｐｈｙｏｉｄｅｓ（Ｃｈｒｉｓｔ）Ｃｈｉｎｇ叶片的上表皮无气孔器,仅具表皮细胞,下表皮由表皮细胞和气孔器组成,气孔指数为２．５。上下表皮细胞和气孔器的细胞中均含有叶绿体。每个气孔器由２个肾形的保卫细胞和２～６个副卫细胞组成,其中以３个和４个副卫细胞的占绝大多数（３细胞的占４５．１％,４细胞的占４３．５％）。从发育上看,气孔器原始细胞进行２次分裂,产生２个保卫细胞和１个同源的副卫细胞。气孔器的发育过程大体可分为４个时期：（１）气孔器原始细胞的分化和分裂期;（２）保卫细胞母细胞成熟期;（３）保卫细胞母细胞分裂和气孔器幼期;（４）气孔器成熟期。狭基巢蕨的气孔器属于中周型     

A comparative study of the hyobranchial apparatus in Hynobiidae (Amphibia: Urodela)

The morphology of the adult hyobranchial apparatus has played an important role in understanding the systematics and evolution of urodeles, but the hyobranchial apparatus of hynobiid salamanders has received little attention so far. In this study, the hyobranchial apparatus of eight hynobiid salamanders (Hynobius leechii, Onychodactylus zhangyapingi, Ranodon sibiricus, Batrachuperus pinchonii, Salamandrella keyserlingii, Liua shihi, Pachyhynobius shangchengensis and Pseudohynobius flavomaculatus) is described and compared based on the clearing and double-staining method. The basic elements of the hyobranchial apparatus of the eight species are similar, including one basibranchial, cornua, one pair of radial loops, one pair of ceratohyals, one pair of hypobranchials II, one pair of ceratobranchials II, one urohyal (absent in O. zhangyapingi), one pair of the complex of hypobranchial I and ceratobranchial I (separated in certain species). Although the hyobranchial apparatus is similar among hynobiid salamanders and shows a unique morphological pattern, there are also certain species-specific distinctions that may be used for specific or generic diagnosis. The results of an ancestral state reconstruction of five traits showed that the ossified basibranchial, the presence of a separated hypobranchial I and ceratobranchial I, the absence of a urohyal, the ossified hypobranchial I and the partially ossified ceratohyal are derived traits. The state shown by the traits of each species is consistent with the phylogenetic position of each species. Compared with other Urodela, the hyobranchial apparatus of this group shows certain distinctive features that may represent the diagnostic characters of the family Hynobiidae. The partially ossified ceratohyal is correlated with the habitat and represents an ecological adaptation.     

Functional changes in the anatomy of the pharyngeal jaw apparatus of Astatoreochromis alluaudi (Pisces, Cichlidae), and their effects on adjacent structures

Organisms are tightly packed with structures so architectonic interdependency of structures is an obvious aspect of integration. This aspect of functional morphology, however, has received remarkably little attention. The present paper presents an example of the spatial relations among several apparatuses in the head of the cichlid fish, Astatoreochromis alluaudi. It investigates the transformations of these apparatuses and their functions due to a change in the pharyngeal jaw apparatus resulting from a functional shift (insect eating to snail crushing or vice versa ). The volume of the pharyngeal jaw apparatus differs 55% between the insect eating- and the snail eating morph. The increase in volume of the pharyngeal jaw apparatus has an impressive number of spatial effects, both direct and indirect, on other structures. Reallocation of space within the pharyngeal jaw apparatus occurs. Total head volume increases 31% but a reallocation of space is still necessary as the increase of the opercular compartment where the pharyngeal jaw apparatus is situated compensates for only 59% of the volume increase of that. Not all spatial effects do impose constraints. Spatial constraints are avoided when one of the apparatuses can use a topographically different volume of space. The respiratory apparatus shows internal reallocations of space without loss of total volume. The same solution occurs for elements of the expansion apparatus and the buccal savity. The eyes are not influenced. Finally spatial effects can have positive repercussions. The muscles of the oral jaw apparatus increase in size. This may be an example of an epiphenomenon.     

Preparatory changes and the development of the conjugation junction in a ciliate,Dileptus

Summary The present observations concern changes in the cortical structure of the ciliateDileptus prior to and during conjugation. The results can be summarized as follows: (1) Mating cells join each other in heteropolar configuration, i.e., the distal part of the oral apparatus of one partner faces the proximal part of the oral apparatus of another partner. (2) The structural changes prior to conjugation occur in the area of the oral apparatus. (3) The bonding area is situated within the oral apparatus, while the oral ciliature that encircles the oral apparatus remains outside the bonding area. (4) The fusion area is formed within the bonding area as a newly formed zone, without cortical organelles typically associated with the cell membrane. Two aspects of the formation of cell-to-cell union inDileptus are discussed: firstly, the heteropolar configuration of mating cells and its possible bearing upon an ability to form double cells when partners separation is inhibited. Secondly, the bonding area ofDileptus is compared to bonding areas of peniculine and hymenostome ciliates. A striking likeness in structural changes was found within the bonding areas of all three ciliates, in spite of the fact that the changes in question are localized within the oral apparatus ofDileptus, while inParamecium andTetrahymena the changed territory is situated between the oral apparatus and the anterior pole of the cell.     

MITOSIS IN THE YEAST LIPOMYCES LIPOFER

A study of mitosis in Lipomyces has been carried out because preliminary observations by Ganesan and Roberts, 1959 (9), had indicated that the nucleus of this yeast might be unusually favourable for morphological observations. This impression has proved correct. The chromosomes of Lipomyces are visible as separate, countable bodies for the greater part of mitosis. The pattern of mitosis differs from the common one in that in Lipomyces the proper distribution of sister chromosomes is accomplished without the help of a spindle apparatus. At the end of prophase sister chromosomes are found in pairs which align themselves parallel to one another to form a palisade or stack whose long axis coincides with the axis of the impending division. At anaphase-telophase the stack of paired chromosomes fuses into a seemingly homogeneous cord which divides by constriction.     

An automated recording incubator for tube culture of microorganisms

Studies on the development of an automated incubator which can perform the operations commonly required for microbiological experiments are described. This apparatus is able to handle a large number of samples and has the unique shaking mechanism which is to strike the lower part of the test tubes with reciprocally moving bars. Besides fundamental operations, such as injection of samples and medium, inoculation and repeated measurements of bacterial growth, the apparatus allows the addition of samples and removal of culture broth at the desired time during the incubation period without the researcher's attendance. These functions are combined to make the apparatus very versatile for microbiological experiments, saving on night-time and holiday working and increasing efficiency in experiments. Some practical applications of this apparatus for microbioassay and fermentation experiments are described. The automated method is shown to be advantageous in assay precision and in obtaining detailed information.     

Phytostat for the growth of lemna in semicontinuous culture with low sulfate

An apparatus is described by means of which Lemna perpusilla 6746 was grown photoautotrophically at a series of constant concentrations of inorganic sulfate, as low as 0.26 μm. Theoretical considerations relevant to this system are discussed and examples of the operation of the apparatus are presented. The data obtained were used to calculate sulfate uptake by the plant colonies as a function of sulfate concentration. The apparatus should be useful for the production of relatively large quantities of Lemna, grown under highly uniform conditions, with or without limitation of one or more nutrient(s). Other small vegetatively reproducing aquatic plants could be similarly studied. Uptake studies could be carried out on a variety of plant materials.     

STRUCTURE AND SIGNIFICANCE OF THE CRYPTOMONAD FLAGELLAR APPARATUS. I. CRYPTOMONAS OVATA (CRYPTOPHYTA)1

The absolute configuration of the flagellar apparatus in Cryptomonas ovata has been elucidated and found to be similar to that reported for Chilomonas paramecium. Variations apparent in the flagellar apparatus of Cryptomonas ovata include the presence of striations in the mitochondrion associated lamella, a rhizostyle which does not bear wing-like extensions from the microtubules and does not lie close to the nucleus, and a striated fibrous anchoring structure associated with one basal body which has not hitherto been described. The flagellar apparatus also includes a four stranded microtubular root which traverses into the anterior dorsal lobe of the cell, a striated fibrous root which is associated with a five stranded microtubular root, and a two stranded Cr root. The homologous nature of these roots to those in the larger cryptomonads is discussed in relation to the apparent reduction in flagellar apparatus size and complexity among the smaller cryptomonads. A diagrammatic reconstruction of the flagellar apparatus of Cryptomonas ovata is also presented.     

THE FLAGELLAR APPARATUS OF GYMNODINIUM SP. (DINOPHYCEAE)1

The detailed structure of the flagellar apparatus has been determined in a small dinoflagellate of the genus Gymnodinium. Although diminutive, this dinoflagellate possesses a complex flagellar apparatus consisting of a posteriorly directed microtubular root, a transverse striated fibrous root, several striated fibrous connectives that attach the basal bodies to one another as well as to the different roots, and a conspicuous non-striated fibrous connective that directly links the posteriorly directded microtubular root with the extended lobe of the nucleus. This represents the second discovery of a nuclear connective linked to the flagellar apparatus in the Dinophyceae but is the first report to elucidate the spatial relationships of the connective with the flagellar apparatus and the cell. A detailed diagrammatic reconstruction is provided and the similarities between these flagellar apparatus features are compared with those known for other dinoflagellates. Additionally, the structure and displacement of the nuclear connective are compared with nuclear connectives described in other protists.     

The ultrastructure of the protonephridial system of Götte's larva of Stylochus mediterraneus (Polycladida, Platyhelminthes)

The protonephridial system of Götte's larva of Stylochus mediterraneus was studied by electron microscopy. There is one protonephridium on each side of the body, formed by one terminal and one canal cell. The terminal filtration apparatus is formed by a single cell (the terminal cell) with several globular processes, the largest of which includes the nucleus. Fingers of cytoplasm (leptotriches) from each process penetrate the lumen surrounding the bundle of cilia and fingers from adjacent processes interdigitate to form a pattern of convoluted slits which constitute the weir. The single canal cell is inserted internally to the terminal cell at the top of the weir and encloses the lumen without a junction. Septate junctions are present between the terminal and canal cells. The lumen of the canal cell is smooth-walled for most of its length and cilia arise and terminate at all levels of the terminal and canal cells. Posterior to the larval mouth opening, the canal cell crosses the epithelium and the lumen ramifies to form the excretory opening. The terminal apparatus closely resembles that found in the freshwater planarian Bdellocephala brunnea .     

Countercurrent chromatography with a new horizontal flow-through coil planet centrifuge

A versatile horizontal flow-through coil planet centrifuge has been introduced for performing countercurrent chromatography. The apparatus carries a pair of coiled separation columns. Both of these allow continuous elution simultaneously without the use of rotating seals. One column enables preparative-scale separations and the other, analytical-scale separations, both with a high partition efficiency comparable to that obtained in liquid chromatography but without the complications arising from the use of solid supports. Capability of the apparatus was demonstrated on separation of dinitrophenyl amino acids using a two-phase solvent system composed of CHCl₃/CH₃COOH/0.1 HCl at a 2/2/1 volume ratio.     

Low density lipoprotein receptor and cation-independent mannose 6- phosphate receptor are transported from the cell surface to the Golgi apparatus at equal rates in PC12 cells

Efficient transport of cell surface glycoproteins to the Golgi apparatus has been previously demonstrated for a limited number of proteins, and has been proposed to require selective sorting in the endocytic pathway after internalization. We have studied the endocytic fate of several glycoproteins that accumulate in different organelles in a variant clone of PC12, a regulated secretory cell line. The cation-independent mannose 6-phosphate receptor and the low density lipoprotein receptor, both rapidly internalized from the cell surface, and the synaptic vesicle membrane protein synaptophysin, were transported to the Golgi apparatus with equivalent, nonlinear kinetics. Transport to the Golgi apparatus (t1/2 = 2.5-3.0 h) was several times faster than turnover of these proteins (t1/2 greater than or equal to 20 h), indicating that transport of these proteins to the Golgi apparatus occurred on average several times for each protein. In contrast, Thy-1, a protein anchored in the membrane by a glycosylphosphoinositide group, was internalized and transported to the Golgi apparatus more slowly than the three transmembrane proteins. Since each of the transmembrane proteins studied showed the same t1/2 for transport to the Golgi apparatus, we conclude that transport of these proteins from the cell surface to the Golgi apparatus does not require sorting information specific to any one of these proteins. These results suggest that one of the functions of late endosomes is constitutive recycling of cell surface receptors through the Golgi apparatus if they fail to recycle to the cell surface directly from early endosomes, and that the late endosome recycling pathway is followed frequently by many rapidly internalized proteins.     

OBSERVATIONS ON THE RELATIONSHIP OF THE GOLGI APPARATUS TO WALL FORMATION IN THE MARINE CHRYSOPHYCEAN ALGA, PLEUROCHRYSIS SCHERFFELII PRINGSHEIM

The role of the Golgi apparatus in wall formation of vegetative cells of a marine chrysophyte, Pleurochrysis scherffelii, is described. Wall fragments are synthesized within the cisternae of the Golgi apparatus. A single Golgi apparatus is always located at the cell periphery, and the distended cisternae are oriented toward the cell surface. A highly-ordered body found near the inflated cisternae is associated with spherical, membrane-bounded bodies which may be involved in the progressive degeneration of cisternal membranes which release wall fragments. Protoplast movement has been detected by time-lapse cinephotomicrography and is correlated at the ultrastructural level with change in positions of the Golgi cisternae. Wall-synthesizing capacity is greatest during transverse wall formation. Senescent cells lack a Golgi apparatus with inflated cisternae. In addition, wall fragments are not present in the Golgi cisternae at this stage. Zoosporogenesis results in a temporary loss of the wall-forming capacity of the Golgi apparatus; this activity then resumes with the formation of a different morphological entity, the scale. Preliminary quantitative measurements of the turnover capacity of the Golgi apparatus have been made. From these data it has been determined that between 41 and 82 Golgi generations are required to synthesize the cell wall of an actively growing cell; this estimate indicates that approximately one cisterna is produced every 2 min, provided the cell generation time is 3 days. The time-lapse cinephotomicrographic data confirm that the rate of production of Golgi cisternae is at least one cisterna every 2 min.     

Construction and application of a modified “gene machine”: A circular concentrating preparative gel electrophoresis device employing discontinuous elution

A modified version of a preparative circular gel electrophoresis apparatus, first described by Edwin Southern (Medical Research Council, University of Edinburgh, Edinburgh, Scotland), has been constructed. The apparatus fractionates a large volume of sample into concentric bands which migrate toward a small circular collection chamber. Samples exiting the gel into the collection chamber are concentrated against a dialysis membrane which encloses the inner electrode and are pumped from this center chamber into a fraction collector at fixed time intervals. The apparatus has been employed to fractionate samples of DNA (10 mg) by electrophoresis through either agarose or acrylamide gels. Two examples of nucleic acids which have been successfully fractionated are given: restriction endonuclease cleavage fragments of total soybean DNA, and a heterogeneous mixture of covalently closed circular plasmid DNA from Bacillus megaterium. Franctionated DNA is suitable for molecular cloning directly from acrylamide and, after one additional treatment, from agarose. The run time for DNA treated with restriction endonuclease is from 24 to 48 h. Purification of 60- to 200-fold is common for a DNA restriction fragment from a total genome.     

THE GOLGI APPARATUS IN NEURONS AND EPITHELIAL CELLS OF THE COMMON LIMPET PATELLA VULGATA

1. In view of widely diverse views held about the identity and structure of the Golgi apparatus in neurons of Mollusca, particularly gastropods, a study has been made on neurons of the common limpet, Patella vulgata, both by light and electron microscopy. A report is given also of observations made on epithelial cells of Patella by electron microscopy. 2. As revealed by Kolatchev's method, the Golgi apparatus in neurons consists basically of black filaments lying to one side of the nucleus. The filaments generally anastomose to form networks of various complexity. Rarely some cells contain only discrete filaments. Associated with some of the filaments is a weakly osmiophilic substance identified as archoplasm. Kolatchev's method also revealed spheroidal bodies (neutral red bodies, "lipochondria," etc.). 3. It has not been possible to demonstrate the Golgi apparatus using either iron-haematoxylin or Sudan black. 4. Examination of Kolatchev's preparations by electron microscopy has revealed that some of the Golgi filaments consist of chromophilic and chromophobic components. The chromophilic component consists of dense lamellae. 5. After fixation in buffered osmium tetroxide solution and examination by electron microscopy, it has been concluded that (a) the chromophilic component of the Golgi apparatus corresponds to a system of paired membranes (which usually enclose an inner dense substance), (b) the chromophobic component corresponds to a substance lying within small dilations of the paired membrane, and (c) the archoplasm corresponds to numerous small vesicles. 6. The paired membranes branch, anastomose, and can often be traced back to a common source. They are interpreted as lamelliform folds, and occasionally tubular processes, of essentially a single Golgi membrane. In cells containing a Golgi network it is suggested that the membrane extends through the whole of the apparatus in such a way that the substance it encloses may be regarded as being in a continuous phase. 7. Epithelial cells of Patella contain a juxtanuclear Golgi apparatus with an ultrastructure similar to that described for neurons.     

Functional morphology of the head of the anabantoid teleost fish Helostoma temmincki

Osteology, myology and motion analysis of the head of the anabantoid fish Helostoma temmincki, a specialized filter feeder, has revealed six functional units: neurocranium, suspensory apparatus, opercular apparatus, hyoid apparatus, branchial apparatus and pectoral girdle. Interactions between the functional units take place through four couplings involved in opening and protruding the jaws. The first coupling is activated in the beginning of the opening cycle by the levator operculi muscle through the opercular apparatus, interoperculomandibular ligament and mandible. The second is activated during feeding by contraction of the sternohyoideus through the hyoid apparatus, interopercular, interoperculomandibular ligament and mandible. The third coupling is active during feeding and “kissing” by contraction of epaxial muscles through mediation of the neurocranium to the jaw apparatus. The fourth coupling is the only one active during air intake and involves contraction of the levator arcus palatini which abducts and rotates the suspensory apparatus forwards, causing the mandible to drop. The retention of isolated ancestral characters during mosaic evolution are explained in terms of the maintenance of couplings which represent functional associations of seemingly remote structures. When natural selection acts on one component of a functional unit or coupling, it essentially acts on all associated elements simultaneously causing character complexes to evolve in common evolutionary trends. It is feasible that functional analysis can separate primary from secondary evolutionary trends.