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At least 883 records · Page 49Linked to original sources
PubMed2005

Age-related changes in the number and structure of synapses in the lip region of the mushroom bodies in the ant Pheidole dentata.

Behavioral development in the worker caste of many adult ants follows a pattern of task transitions that contribute to the division of labor within colonies. In the ant Pheidole dentata, the number of tasks that minor workers attend to increases as they progress from brood-care activities within the nest to acts outside the nest such as foraging and defense. In this study we investigated synapse maturation in the lip region of mushroom bodies in young and old minor workers because of its potentially crucial role in behavioral development, task performance, and repertoire expansion. As minor workers aged, individual presynaptic boutons enlarged and acquired more synapses and vesicles, but the total number of synapses in the lip region did not change significantly. Glial cell processes occupied less of the synaptic neuropil as ants matured. These findings indicate an expansion and enhancement of efficacy at specific sets of synaptic connections between the projection interneurons and Kenyon cell dendrites and a commensurate loss of other connections as minor workers age and expand their behavioral repertoire.

Age Factors↗
PubMed2006

Bridging behavior and physiology: ion-channel perspective on mushroom body-dependent olfactory learning and memory in Drosophila.

An important body of evidence documents the differential expression of ion channels in brains, suggesting they are essential to endow particular brain structures with specific physiological properties. Because of their role in correlating inputs and outputs in neurons, modulation of voltage-dependent ion channels (VDICs) can profoundly change neuronal network dynamics and performance, and may represent a fundamental mechanism for behavioral plasticity, one that has received less attention in learning and memory studies. Revisiting three paradigmatic mutations altering olfactory learning and memory in Drosophila (dunce, leonardo, amnesiac) a link was established between each mutation and the operation of VDICs in Kenyon cells, the intrinsic neurons of the mushroom bodies (MBs). In Drosophila, MBs are essential to the emergence of olfactory associative learning and retention. Abnormal ion channel operation might underlie failures in neuronal physiology, and be crucial to understand the abnormal associative learning and retention phenotypes the mutants display. We also discuss the only case in which a mutation in an ion channel gene (shaker) has been directly linked to olfactory learning deficits. We analyze such evidence in light of recent discoveries indicating an unusual ion current profile in shaker mutant MB intrinsic neurons. We anticipate that further studies of acquisition and retention mutants will further confirm a link between such mutations and malfunction of specific ion channel mechanisms in brain structures implicated in learning and memory.

Animals↗
PubMed2002

Hydroxyurea-induced partial mushroom body ablation in the honeybee Apis mellifera: volumetric analysis and quantitative protein determination.

Hydroxyurea (HU) treatment of first instar honeybee larvae was previously shown to cause mushroom body (MB) ablations. Predominantly, either one or both median MB subunits were ablated. This prompted us to analyze the effects of asymmetrical or symmetrical HU-induced MB ablation on both the morphology of the brain and on the level of three proteins (synapsin, PKA RII, and PKC), which are considered to play a role in synaptic plasticity, learning, and memory. In brains with one median MB subunit missing the volume of the overall MB calyx neuropil in the lesioned side was diminished by 35%. This strong reduction occurred although the remaining lateral MB calyx of the lesioned brain side was found to be significantly larger than that of the intact side. Accordingly, in brains with both median MB subunits missing the size of the remaining lateral calyces increased. The various types of MB ablation differentially affected the amounts of synapsin, PKA RII, and PKC expressed in the central brain. In animals with bilateral and thus symmetrical MB ablation (both median calyces ablated) the protein amount was found to be similar to that in control animals. However, unilateral MB ablation causes an increase in the amounts of the tested proteins in the intact brain side, while the levels in the ablated side were the same as in control animals. These findings not only show that HU-induced ablation of MB subunits is accompanied by volume changes and by changes in protein expression, but also suggest that these processes are highly regulated between the brain sides. The latter is of general importance in understanding the potential contribution of the MB subunits to learning and memory and their interaction between the brain sides.

Animals↗
PubMed2002

Hydroxyurea-induced partial mushroom body ablation does not affect acquisition and retention of olfactory differential conditioning in honeybees.

The mushroom bodies (MBs), a paired structure in the insect brain, play a major role in storing and retrieving olfactory memories. We tested whether olfactory learning and odor processing is impaired in honeybees in which MB subunits were partially ablated. Using hydroxyurea (HU) to selectively kill proliferating cells, we created honeybees with varying degrees of MB lesions. Three-dimensional reconstructions of brains were generated to analyze the drug-induced morphological changes. These reconstructions show that, with few exceptions, only the MBs were affected by the drug, while other brain areas remained morphometrically intact. Typically, lesions affected only the MB in one hemisphere of the brain. To preclude HU-induced physiologic deficits in the antennal lobe (AL) affecting olfactory learning, we measured the responses to odors in the AL using an in vivo calcium imaging approach. The response patterns did not differ between the AL of intact versus ablated brain sides within respective specimens. We, therefore, carried out side-specific classical discriminative olfactory conditioning of the proboscis extension reflex (PER) with control bees and with HU-treated bees with or without MB ablations. All experimental groups learned equally to discriminate and respond to a rewarded (CS+) but not to an unrewarded (CS-) conditioned stimulus during acquisition and retention tests. Thus, our results indicate that partial MB lesions do not affect this form of elemental olfactory learning.

Animals↗
PubMed2003

20-Hydroxyecdysone inhibits the mitotic activity of neuronal precursors in the developing mushroom bodies of the honeybee, Apis mellifera.

The mushroom bodies (MBs) within the brain of the honeybee, Apis mellifera, are prominent paired neuropil structures consisting of a lateral and a median subunit. The intrinsic MB neurons (Kenyon cells) of each of these subunits are generated in four distinct proliferation centers, each associated with a calyx. Previous BrdU studies revealed that neurogenesis of Kenyon cells starts at the first larval stage (L1) by symmetrical cell division of Kenyon precursor cells, and ceases abruptly at a midpupal stage (P5). In the present work, we confirmed these results using the antiphospho histone H3 mitosis marker to label mitotically active cells in a cell culture system, in histological sections, and in whole-mount brain preparations. To elucidate whether the steroid hormone ecdysone plays a role in the termination of Kenyon cell neurogenesis, we manipulated the hormone titer by injecting 20-hydroxyecdysone (20E) into animals of those pupal stages (P0/1, P3, P4) in which neurogenesis of Kenyon cells was still extensive. The effects of 20E were evaluated by determining the number of mitotically active cells in confocal microscopic images of squash preparations of the MB proliferation centers. In all pupal stages studied, 20E caused a reduction of mitotic activity, indicating its involvement in the cessation of Kenyon cell neurogenesis.

Animals↗
PubMed2003

Gain-of-function screen identifies a role of the Src64 oncogene in Drosophila mushroom body development.

Mushroom bodies (MB) are substructures in the Drosophila brain that are essential for memory. At present, MB anatomy is rather well described when compared to other brain areas, and elucidation of the genetic control of the development and projection patterns of MB neurons will be important to the understanding of their functions. We have performed a gain-of-function screen in order to identify genes that are involved in MB development. We drove expression of genes in MB neurons by crossing 2407 GAL4-driven UY element lines to lines containing an MB GAL4 source and UAS-GFP elements, and looked for defects in the MB structure. We have molecularly identified the genomic regions adjacent to the 26 positive UY insertions and found 18 potential genes that exhibit adult MB gain-of-function phenotypes. The proteins encoded by these candidate genes include, as well as genes with yet unknown function, transcription factors (e.g., tramtrack), nanos RNA-binding protein, microtubule-severing protein, vesicle trafficking proteins, axon guidance receptor, and the Src64 cytoplasmic protein tyrosine kinase. These genes are involved in key features of neuron cell biology. In three cases, tramtrack, nanos, and Src64, we show that the open reading frame located directly downstream of the UY P element is indeed the expressed target gene. Loss-of-function mutations of both ttk and Src64 lead to MB phenotypes proving that these genes are involved in the genetic control of MB development. Moreover, Src64 is shown here to act in a cell-autonomous fashion and is likely to interact with the previously-identified linotte/derailed receptor tyrosine kinase in MB development.

Animals↗
PubMed2005

Centrophobism/thigmotaxis, a new role for the mushroom bodies in Drosophila.

Insects, like vertebrates, exhibit spatially complex locomotor activity patterns when foraging or navigating. Open field studies recently showed that Drosophila avoids central zones and stays at the periphery, an effect that can be interpreted as centrophobism and/or thigmotaxis. In this study, we further characterized this phenomenon and studied the responsible underlying neural mechanisms. The implication of the Drosophila mushroom bodies (MBs) in olfactory learning and memory processes is well documented. In an open field situation in which fly locomotor activity is recorded by video tracking, we show that center avoidance is greatly diminished in flies with hydroxyurea-ablated MBs, suggesting a new role for these structures. Furthermore, the temperature-sensitive allele of the dynamin gene shibire was expressed in various enhancer-trap P[GAL4] lines, disrupting synaptic transmission in different MB lobes. Specifically blocking the gamma lobes alters centrophobism/thigmotaxis while blocking the alpha/beta lobes does not, suggesting a functional specialization of MB lobes. Drosophila may serve as a new model system for elucidating the genetic and neural bases of such complex phenomena as centrophobism/thigmotaxis.

Analysis of Variance↗
PubMed1986

Early detection of amatoxins in human mushroom poisoning.

Amatoxins were detected radioimmunologically as early as 90-120 min after ingestion in the gastric fluid and urine of a 15-year-old boy who tried to commit suicide by ingestion of wild mushrooms. This early detection of amatoxins in the urine is proof of rapid absorption from the intestinal tract and subsequent excretion by the kidneys in man.

Adolescent↗
PubMed1989

Fatal mushroom poisoning in Barcelona, 1986-1988.

In 1986-88, 46 poisonings (4 of which were fatal) caused by amatoxin mushroom were reported. The fatalities were males aged between 7 and 65 years. They all had gastrointestinal symptoms and three of the patients died of acute hepatic insufficiency. The fourth died as a result of an intestinal perforation. The clinical and pathological alterations are compared with the findings of other authors.

Adolescent↗
PubMed1989

Hepatotoxic mushroom poisoning: diagnosis and management.

Hepatotoxic mushroom poisoning (due to Amanita, Lepiota and Galerina species) may be considered as a real medical emergency, since an early diagnosis and immediate treatment are required for a successful outcome. In this review the physio-pathological features and the clinical picture of amatoxin poisonings are described as the basis for diagnosis and therapeutic decisions. The treatment schedule proposed is analyzed in some points: Symptomatic and supportive measures, toxin removal and extraction procedures, and the possibility of using antidotes. Some parameters with prognostic significance are commented on. Finally, the mortality rate and its evolution throughout the present century is also considered.

Amanitins↗
PubMed1995

Intensive hemodialysis and hemoperfusion treatment of Amanita mushroom poisoning.

Over a period of fifteen years, 41 patients including 23 males and 18 females with Amanita mushroom poisoning were treated at the University Hospital of Lund, Sweden. The intensity of poisoning was graded according to serum transaminase elevations and prothrombin time reductions. Severity was mild in 16 patients (Group A), moderate in 14 (Group B) and severe in 11 (Group C). Members of Group C reported shorter latency periods before the onset of symptoms, (10 +/- 1 hours, P < 0.05) and longer delays in treatment, (34 +/- 4 hours), than did the other patients. Intensive treatment was begun before the results of urine amatoxin assay were reported. Treatment consisted of: fluid and electrolyte replacement, oral activated charcoal and lactulose, i.v. penicillin, combined hemodialysis and hemoperfusion in two 8 hour sessions, some received i.v. thioctic acid, other i.v. silibinin, all received a special diet. This combination of treatment modalities was used to accelerate the elimination of amatoxin from the patients' bodies. The longest period of hospitalization, 13 +/- 2 days, was required by the patients of Group C (p < 0.01). All patients improved and were discharged from the hospital asymptomatic. No sequelae were later reported for the majority of those moderately and severely poisoned. We have concluded that intensive combined treatment applied in these cases is effective in relieving patients with both moderate and severe amanitin poisoning.

Adult↗
PubMed1986

Clinical findings and follow-up evaluation of an outbreak of mushroom poisoning--survey of Amanita phalloides poisoning.

One hundred and sixty cases of mushroom poisoning during the period July-November 1981 are reported. The survey details 116 observations of short incubation syndromes and 44 cases of delayed syndrome, identified as Amanita Phalloides poisoning. Of the latter, 40 patients were adult (mean age 46 years, range 20-77; 18 females and 22 males) and 4 were children (less than or equal to 12 years old; 3 females and 1 male). All the patients with Amanita Phalloides poisoning were treated according to a therapeutic protocol, based on the infusion of high doses of penicillin G, administration of dexamethasone and thioctic acid, careful correction of water and electrolyte unbalance. The severity of the disease varied in the population of 44 patients: 4 patients died (2 females, 10 and 77 years old; 2 males, 56 and 64 years old); 26 patients were discharged from the hospital as clinically cured; 14 were discharged with persistently abnormal levels of transaminases and they were advised of a follow-up evaluation. The average length of stay in hospital was 2 weeks. Of the patients followed-up, 6 were symptom-free after 6 months, with normal transaminase values and a normal histopathological picture of liver biopsy specimens. In the remaining patients, there was no normalization of transaminase values and liver biopsy specimens showed a picture of chronic active hepatitis. These patients displayed abnormal immunological tests, with presence of immune complexes and of anti-smooth muscle autoantibodies. The results indicate that Amanita Phalloides poisoning represents a threat not only in the high mortality acute phase, but also in the development of chronic active hepatitis in some survivors.

Adolescent↗
PubMed1986

Severe hemolysis caused by antibodies against the mushroom Paxillus involutus and its therapy by plasma exchange.

It has been shown that fatal "poisoning" with the mushroom species Paxillus involutus is caused by antibodies against the fungus in sensitized patients. Because circulating immune complexes play an important role, therapeutic procedures which can eliminate those complexes could stop immune hemolysis. A 37-year-old patient became severely ill after repeated ingestion of sufficiently cooked Paxillus involutus. As a result of hemolysis with reversible shock symptoms, acute renal failure developed. Plasma exchange with 3,000 ml albumin 5% was carried out daily during the first 3 days after admission. Each plasma exchange lowered free hemoglobin and immune complex levels by 60%-75%. Acute renal failure was successfully treated with hemodialysis. Specific IgG-antibodies against membrane particles of Paxillus involutus were detected by hemagglutination tests in the serum of the patient. The sequence of reactions resulting from the testing procedures strongly suggests the formation of immune complexes. These complexes are likely to bind to erythrocytes acting as innocent bystanders. Activation of the complement system finally results in hemolysis and shock. In addition to adequate shock treatment elimination of these immune complexes by plasma separation seems to be the therapy of choice.

Adult↗
PubMed1984

Ethanol diminishes the toxicity of the mushroom Amanita phalloides.

Survival of mice after lethal doses of a lyophilizate from Amanita phalloides ('death cap') was markedly increased by single doses of ethanol applied 30 min before or 5 min after the mushroom. Hepatic histopathological damage (confluent necrosis) was largely prevented. Acute, but not chronic, consumption of ethanol may thus influence favorably the outcome of death cap poisoning and should be taken into consideration in the evaluation of therapeutic measures.

Amanita↗
PubMed1984

Mushroom toxins of the genus Cortinarius.

3 major components of the toxic fungus Cortinarius speciosissimus have been isolated and their structures determined as cyclic polypeptides. 2 of these compounds have been shown in laboratory animals to cause nephrotoxicity characteristic of Cortinarius mushroom poisoning.

Amino Acid Sequence↗
PubMed1977

Ethanol and tolerated doses of Amanita phalloides protect against lethal doses of the mushroom.

Single tolerated doses of a lyophilizate from Amanita phalloides (ADL) failed to increase the survival rate of mice after the LD90 of the mushroom. Also, pretreatment with large doses of ethanol did not protect against lethal doses of APL. However, with combined administration of single tolerated doses of APL and of ethanol, the survival rate of mice after a lethal challenge with APL was increased from 13% to up to 100%. Both ethanol and APL potentiated the effect of barbiturate narcosis, but the combined pretreatment was not more effective. The protection against APL afforded by the combined regimen may be due to inhibition of activating hepatic microsomal enzymes, but biochemical studies are needed to support this hypothesis.

Amanita↗
PubMed1996

[Indications for liver transplantation in severe amanita phalloides mushroom poisoning].

The clinical course of 12 patients with mushroom poisoning was evaluated in order to define the parameters considered to be relevant to the indication for liver transplantation. Eight patients recovered under conservative therapy; one patient died due to pre-existing, concomitant cardiopulmonary disease. In three patients transplantations had to be performed because of severe liver failure. On admission, the transplanted patients had a decreased Quick's test score and factor V value (< 10%). The peak of liver enzymes, serum bilirubin, serum creatinine, partial thromboplastin time and azotemia were not of any prognostic value. Main indications for liver transplantation were a very low initial Quick's test score and factor V value (both < 10%) and their inadequate response under substitution therapy. The development of encephalopathy and renal failure were further parameters indicating poor prognosis.

Adolescent↗
PubMed2006

[End stage renal disease after ingestion of mushrooms].

This case report describes a 56 year old patient with acute renal failure caused by a mushroom poisoning. Unspecific symptoms like a gastroenteritis followed by kidney insuffiency lead to the diagnosis of an orellanus syndrome. The toxin can be proved by thin layer chromatography in renal biopsy. Fast processing of hemoperfusion may avoid lasting kidney damage and dialysis.

Humans↗