Methods to investigate the structure and connectivity of the nervous system

Understanding the computations that take place in neural circuits requires identifying how neurons in those circuits are connected to one another. In addition, recent research indicates that aberrant neuronal wiring may be the cause of several neurodevelopmental disorders, further emphasizing the importance of identifying the wiring diagrams of brain circuits. To address this issue, several new approaches have been recently developed. In this review, we describe several methods that are currently available to investigate the structure and connectivity of the brain, and discuss their strengths and limitations.     

Mate Guarding in the Cricket Gryllodes sigillatus: Influence of Multiple Potential Partners

There are several hypotheses as to the function of postcopulatory mate guarding. Control over the mate-guarding period by either sex could potentially influence relative reproductive success. Mate-guarding behaviour in Gryllodes sigillatus was studied under several conditions: 1. undisturbed pairs; 2. pairs with a single male intruder; 3. pairs exposed acoustically, visually and olfactorily to several other males; 4. pairs exposed freely to several other males; and 5. pairs exposed freely to several other females. The results provide support for the spermatophore retention and rival defence hypotheses. The efficacy of mate guarding was not compromised by the pair being in acoustic, visual and olfactory contact with several other males. Once pairs were exposed to free contact with several other males, the spermatophore retention time by the female declined significantly, indicating that the mate guarder's efficiency declines under competition from several rivals. In pairs exposed to contact with several females after mating, the mate-guarding period and spermatophore retention time declined as the mate guarder abandoned the mated female and pursued the other females. Termination of the effective mate-guarding period by either sex seems to be influenced by the number of other potential partners present.     

mvaT mutation modifies the expression of the Pseudomonas aeruginosa multidrug efflux operon mexEF-oprN

Pseudomonas aeruginosa carries several multidrug efflux operons, including mexEF-oprN, that contribute to its resistance to multiple antibiotics. mvaT affects the expression of several P. aeruginosa genes. In this study, we show that the mvaT mutant PAODeltamvaT is more resistant than its parent PAO1 strain to chloramphenicol and norfloxacin but more sensitive to imipenem; yet both were less resistant to chloramphenicol, norfloxacin, and imipenem than 'typical'nfxC-type mutants. Neither strain carries the deletion described for nfxC-type mutants in mexT, the mexEF-oprN regulatory gene. Expression of mexEF-oprN is increased by five- to sixfold in PAODeltamvaT, while the expression of oprD is reduced by approximately twofold. mvaT mutation had no effect on the expression of other multidrug resistance operons, although it increased the expression of several ATP-binding cassette transporter genes. We show that mvaT mutation does not affect mexEF-oprN expression through mexT or mexS. We also explored several other potential mechanisms.     

Origin of the duplicated regions in the yeast genomes

The genome of Saccharomyces cerevisiae contains several duplicated regions. The recent sequencing results of several yeast species suggest that the duplicated regions found in the modern Saccharomyces species are probably the result of a single gross duplication, as well as a series of sporadic independent short-segment duplications. The gross duplication might coincide with the origin of the ability to grow under anaerobic conditions.     

Identification and expression of the motilin precursor in the guinea pig

Motilin has never been isolated from rodents, the most frequently used laboratory animals, despite several attempts. We have isolated and sequenced the motilin precursor from duodenal mucosa of guinea pig (GenBank accession number AF323752) and studied its expression in several tissues. The percent homology with human motilin is the lowest yet observed due to several unique substitutions in the C-terminal end. As expected, the precursor was present in the gut mucosa with the exception of the gastric corpus. It was also present in medulla oblongata, nucleus of the solitary tract, hypophysis, spinal cord, hypothalamus, and cerebellum but not in the cerebral cortex. For the first time we demonstrated motilin expression in the thyroid.     

The connection of the annual periodical rhythm of vegetation with the changes of the blocking (constriction) of the horizon in the plant associations of several layers of the danube Island at Göd

Summary In our study we presented a method which in the investigation of the annual periodical rhythm of vegetation might facilitate an approach to clarify the significance of insolation energy. Investigations were carried out first of all in plant associations of several layers (flood plain forest, Salicetum triandrae) to point out the changes in insolation energy playing an important part in the alternation of the individual aspects.If it is intended to become acquainted with and to compare the insolation supply of the lower layer of the plant associations of several layers, our method based on the analysis of the constriction of the horizon supplies several useful points of support.In the course of this study we obtained data on the reduction of the astronomically possible duration of sunshine, upon the action of the constriction of the horizon and on the duration of insolation getting through into the lower storeys. On the basis of our surveys we determined with satisfactory accuracy for the construction of a general picture the amount of actual insolation reaching the lower strata of the stands in Kcal/sq.m.     

Characterization of the DOC1/APC10 subunit of the yeast and the human anaphase-promoting complex.

The anaphase-promoting complex/cyclosome (APC) is a ubiquitin-protein ligase whose activity is essential for progression through mitosis. The vertebrate APC is thought to be composed of 8 subunits, whereas in budding yeast several additional APC-associated proteins have been identified, including a 33-kDa protein called Doc1 or Apc10. Here, we show that Doc1/Apc10 is a subunit of the yeast APC throughout the cell cycle. Mutation of Doc1/Apc10 inactivates the APC without destabilizing the complex. An ortholog of Doc1/Apc10, which we call APC10, is associated with the APC in different vertebrates, including humans and frogs. Biochemical fractionation experiments and mass spectrometric analysis of a component of the purified human APC show that APC10 is a genuine APC subunit whose cellular levels or association with the APC are not cell cycle-regulated. We have further identified an APC10 homology region, which we propose to call the DOC domain, in several protein sequences that also contain either cullin or HECT domains. Cullins are present in several ubiquitination complexes including the APC, whereas HECT domains represent the catalytic core of a different type of ubiquitin-protein ligase. DOC domains may therefore be important for reactions catalyzed by several types of ubiquitin-protein ligases.     

Multiple roles of the gene zinc finger homeodomain-2 in the development of the Drosophila wing

The gene zfh2 and its human homolog Atbf1 encode huge molecules with several homeo- and zinc finger domains. It has been reported that they play important roles in neural differentiation and promotion of apoptosis in several tissues of both humans and flies. In the Drosophila wing imaginal disc, Zfh2 is expressed in a dynamic pattern and previous results suggest that it is involved is proximal–distal patterning. In this report we go further in the analysis of the function of this gene in wing development, performing ectopic expression experiments and studying its effects in genes involved in wing development. Our results suggest that Zfh2 plays an important role controlling the expression of several wing genes and in the specification of those cellular properties that define the differences in cell proliferation between proximal and distal domains of the wing disc.     

Metameric components of the occipital region of the polypterids (Pisces)]

Investigations into the development of the pronephros in Polypterus senegalus senegalus Cuvier have shown several details on the composition of the occipital region of this fish. It has been shown that the first six metotic metameres contribute to the structuring of the occipital region. These six metameres also are responsible for the existence of the pronephros. The epimeres of metamere I atrophies in the beginning of larval life. The muscular structures derived from the four following metameres become englobed in the occipital region. In the myoseptum between the previous metameres V and VI the post-occipital semi-vertebra, a pecularity of Polypterus, arises. The first vertebra of the column arises between structures that are derived from the previous metameres VI and VII. Such statements have been possible by a close examination of the disposition of the pectoral fin nerves in several larval stages. Because these nerves have been labelled with different names in several studies, a comparison of these names has been necessary.     

The importance of the Maillard reaction in ophtalmology

Non enzymatic glycosylation( glycation) of proteins, described by L. C. Maillard in 1912, results in the formation of advanced glycation end products (AGE-s). These exhibit a number of harmful reactions, increasing with age and involved in several age-associated pathologies. In ocular pathology, their role was demonstrated at several levels of age-associated eye-diseases, such as the rigidification of cornea, in the separation of vitreous fibers from the hyaluronan jelly, which might result in retinal detachment. AGE-s are involved also in retinal microvascular alterations in diabetics as well as in age-related macular degeneration. We compared the cytotoxic effect of several AGE-s on human skin fibroblasts and corneal keratocytes. Keratocytes were shown to be much more resistant to the cytotoxic effect of several AGE-products than fibroblasts. This higher resistance of keratocytes to the free radical mediated cytotoxic effect of AGE-s might be the result of the constant exposure of cornea to UV-light possibly mediating the appearance of more efficient protective mechanisms during evolution.     

Variations in the catabolism of the acetylcholine receptor during aging

The time and modalities of degradation of the muscles acetylcholine receptor have been studied by several investigator, both in vivo and in vitro and under normal and pathological condition. The metod employed in this study for assessment of possible changes in the degradation to age involves the valutation of several parameters. These are explained and discussed. The preliminary results show the turnover of the receptor for junction acetylcholine, which is known to be considerably accellerated in conditions such denervation and myastenia, is slowed down during senescence.     

Correlation between the size,shape and position of the teeth on the jaws and the bite force in Theropoda

Theropods have fascinated both paleontologists and the general public due to their large diversity of sizes and morphologies. They also present a large variation in tooth morphologies. Previous studies have estimated the bite force of several specimens. The goal of this study is to determine if there is a correlation between the tooth size, shape and position on the skull and mandible and the bite force of these dinosaurs. Measurements were made on several theropods, including the bending strength of the teeth on the anterior-posterior and the mediolateral axes of the jaws, as well as the bending strength of the mandible, and were compared to fossil and modern Crocodylia. We observed that several bending strength maxima of the teeth trends were aligned with key areas of the mandible, and that the size, shape as well as the position of the teeth on the jaws were correlated with the bite force of both Crocodylia and theropods, which can be related to their diet and feeding habits.     

兔核移植胚胎蛋白质变化的电泳分析

采用ＳＤＳ－聚丙烯酰胺凝胶电泳及银染法,对兔核移植胚胎蛋白质合成类型的变化进行了研究。结果表明,“原核”期核移植胚胎中有几种蛋白质与核供体桑椹胚及受体卵母细胞的蛋白质类型明显不同,与同期受精卵中蛋白质类型相似,但在某些带上也有质或量的差别。结果提示,供体核基因表达被卵母细胞质所重排,但并非很完全。本文还对提高兔核移植胚胎发育能力可能的途径进行了讨论。     

Effect of Paper on the Performance Assay in the Control of Antibiotic Sensitivity Discs

Antibiotic discs were prepared, using several several batches of papers meeting Food and Drug Administration specifications. The analysis of 1,152 zones of inhibition produced showed no performance differences among these batches. Other discs were prepared using papers of different grades. These produced large differences in performance. It is obvious, therefore, that the use of a specified disc paper is necessary for standardizing the performances of the products of various manufacturers and that reproducible results can be attained with the grade of paper specified.     

The mono- and polysynaptic connections between identified neurons in the system of the passive defensive reflex in the edible snail]

A structure of synaptic connections between the identified sensory and giant command neurons of Helix lucorum was studied. It was found that EPSPs arising in the giant neuron as responses to single action potentials generation in sensory neuron consist of several monosynaptic and several polysynaptic components having different magnitude, latencies, and plasticity. The latencies of monosynaptic components are determined by different presynaptic terminals' lengths.     

Opa-like repeats in the genome of the Medfly Ceratitis capitata

The sequence determination of several genomic clones isolated from the Mediterranean fruitfly Ceratitis capitata identified the existence of opa-like repeats, often more than one being clustered in small chromosomal segments. These repeats have previously been shown to consist of stretches of tandemly reiterated glutamine-encoding residues, and they are found in multiple genes of several organisms. Most of the repeats described here are flanked or interrupted by stop codons in all reading frames and, thus, could not possibly be part of protein-coding sequences. Furthermore, these repeats, of which there are several hundred in the genome of the Medfly, can be used effectively for the determination of sequence polymorphisms, providing a convenient approach to obtain additional landmarks for the construction of genomic maps of this economically important insect.This paper is dedicated to the memory of our colleague and friend Dr. Jim Flach who took part in the initial phase of this work and died during the course of the investigation.     

Current status of the endocrinological effects of vasectomy

The relevant literature which has appeared, primarily within the last several years, in regard to the endoncrinological effects of vasectomy is reviewed. Focus is on early animal studies, examinations of interstitial tissue, short-term endocrine studies in animals and man, and long-term endocrine studies in man. Suspicion that vasectomy may influence androgen and gonadotropin status has reappeared recently because of experimental investigations of vasectomized rats and human vasectomy follow-up studies. The possibility that vasectomy is accompanied by untoward consequences to the endocrine system, which might become manifest shortly after the procedure or later in life, received support from recent animal investigations. During the 1972-1975 period, several reports appeared which attempted to clarify what effect vasectomy had upon the human pituitary-gonadal axis. Recently, there have been several prospective long-term studies on the pituitary-testicular axis in vasectomized men. Several areas where additional research is necessary are identified.