Can the function of the extirpated amygdaloid complex be compensated for by the transplantation of embryonic nerve tissue?

In 20 white rats bilateral coagulation of the amygdalar complex was produced; on the fifth day to one half of them transplantation was performed by introducing stereotaxically on the left side 0.2-0.5 mm3 of the brain embryonal tissue from the corresponding area of the amygdala of 20-days embryo; in control saline was administered. After two months the rats were sacrificed to determine the activity of antiradical defense by superoxide dismutase (SOD) and the level of lipids peroxide oxidation (LPO) in the cerebral cortex. The transplantation decreased LPO even more and increased SOD as compared to amygdalectomy, e. i. caused still greater deviations from the norm (in this meaning--paradoxal effect), what apparently corresponds to intensification of adaptative-compensatory processes caused by amygdalectomy. The transplantation did not reverse the rats behaviour to the initial one and did not eliminate memory defect in the test of conditioned reaction of passive avoidance (like pyrazetam); it had different direction influence on "drinking under current" in conflict situation, only in particular cases approaching it to the norm.     

Study of the emission characteristics of a low-pressure discharge in crossed E × H fields by using an echelle spectrograph with compensated astigmatism

In order to prove that thermal ionization is the main mechanism for sustaining a high-current low-pressure diffuse discharge in crossed E × H fields, the ion temperature was estimated by analyzing the Doppler broadening of a spectral line. The emission spectrum from discharge plasma was recorded using a specially designed echelle spectrograph with compensated astigmatism and with a resolution of 0.02 nm.     

The LSP1-α gene is not dosage compensated in the Drosophila melanogaster species subgroup

The X-linked subunit of larval serum protein 1 (LSP1-) is shown to lack dosage compensation in six members of the melanogaster species subgroup, viz., Drosophila melanogaster, D. simulans, D. mauritiana, D. erecta, D. yakuba, and D. teissieri, by quantitative filter hybridization and by electrophoretic and autoradiographic analyses of fat body proteins. These results support the hypothesis that there is little selection pressure on the LSP1- gene to acquire dosage compensation.H.W.B. acknowledges a Commonwealth Scholarship. This work was supported by an SRC grant to D.B.R.     

Territorial polygyny in house wrens: are females sufficiently compensated for the cost of mate sharing?

We tested two hypotheses to explain the occurrence of polygynyin a box-nesting population of the house wren (Troglodytes aedon),a small, insectivorous songbird. Some proportion of femalesin this population routinely settle with already-mated maleseven though unmated males hold territories relatively shortdistances away. The "polygyny-threshold" hypothesis proposesthat mated males possess territorial resources that compensatefemales for the cost of mate sharing (i.e., reduced aid in feedingyoung). Contrary to a key prediction of this hypothesis, however,we found that secondary females produced fewer offspring thanfemales who chose nearby unmated males. The "sexy son" hypothesisproposes that mated males father attractive, prolific sons,which results in secondary females obtaining as many grandoffspringas expected had they chosen available unmated males. Our datasuggest that if male mating success is at least moderately heritable,secondary females may produce enough fledglings per breedingattempt relative to their monogamously mating counterparts torecoup fitness losses in the next generation. However, fullacceptance of this hypothesis must await confirmation that malemating success is heritable. We suggest a third hypothesisfor why females readily mate polygynously when better, monogamousbreeding options are clearly available. We argue that femalesmay choose mated males because these males possess highquality nest sites (i.e., nest-boxes), and that access to such nestsites would provide females with sufficient compensation forthe costs of polygyny under normal conditions when all availableunmated males would have poorer-quality, natural nest sites.This "expected compensation" hypothesis assumes that polygynouslymating females terminate mate search before they discover thatavailable unmated males also possess nestboxes. A recent theoreticalexploration of mate search strategy suggests that this assumptionis reasonable.     

The loss of Y-sperm in “sex ratio” (SR) males of Drosophila subobseura is compensated

In Drosophila subobscura sex ratio (SR) males, a mechanism compensating for the loss of Y-sperm is present since these males produced a higher number of female offspring than did males of three control strains. Moreover, the number of female offspring from SR-males was even higher (average 1719) than the number of female and male offspring together (average 1460) from T2, one of the control strains. The fertile life span of SR-males was found to lie between those of the control strains. The rate of insemination was the same for SR- and control males.     

Feeling by sight or seeing by touch?

We have addressed the role of occipital and somatosensory cortex in a tactile discrimination task. Sight-ed and congenitally blind subjects rated the roughness and distance spacing for a series of raised dot patterns. When judging roughness, intermediate dot spacings were perceived as being the most rough, while distance judgments generated a linear relation. Low-frequency rTMS applied to somatosensory cortex disrupted roughness without affecting distance judgments, while rTMS to occipital cortex disrupted distance but not roughness judgments. We also tested an early blind patient with bilateral occipital cortex damage. Her performance on the roughness determination task was normal; however, she was greatly impaired with distance judgments. The findings suggest a double-dissociation effect in which roughness and distance are primarily processed in somatosensory and occipital cortex, respectively. The differential effect of rTMS on task performance and corroborative clinical evidence suggest that occipital cortex is engaged in tactile tasks requiring fine spatial discrimination.     

Neuronal death induced by nanomolar amyloid β is mediated by primary phagocytosis of neurons by microglia

Alzheimer disease is characterized by neuronal loss and brain plaques of extracellular amyloid β (Aβ), but the means by which Aβ may induce neuronal loss is not entirely clear. Although high concentrations of Aβ (μM) can induce direct toxicity to neurons, we find that low concentration (nM) induce neuronal loss through a microglia-mediated mechanism. In mixed neuronal-glial cultures from rat cerebellum, 250 nM Aβ1-42 (added as monomers, oligomers or fibers) induced about 30% loss of neurons between 2 and 3 days. This neuronal loss occurred without any increase in neuronal apoptosis or necrosis, and no neuronal loss occurred with Aβ42-1. Aβ greatly increased the phagocytic capacity of microglia and induced phosphatidylserine exposure (an "eat-me" signal) on neuronal processes. Blocking exposed phosphatidylserine by adding annexin V or an antibody to phosphatidylserine or inhibiting microglial phagocytosis by adding either cytochalasin D (to block actin polymerization) or cyclo(RGDfV) (to block vitronectin receptors) significantly prevented neuronal loss. Loss of neuronal synapses occurred in parallel with loss of cell bodies and was also prevented by blocking phagocytosis. Inhibition of phagocytosis prevented neuronal loss with no increase in neuronal death, even after 7 days, suggesting that microglial phagocytosis was the primary cause of neuronal death induced by nanomolar Aβ.     

Some properties of auditory neuron’s model trained by firing caused by tones modulated by low-frequency noise

In many sensory systems the formation of burst firing can be observed along a way from the periphery to the central nuclei. We investigate the putative transformation of spontaneous activity in the auditory pathway using a neuron model trained by real firing recorded in the auditory nuclei of the frog. The model has 200 separate inputs (neuronal spines). It is supposed that every spine is a coincidence detector. Its output (synaptic potential) sharply increases at emergence of the precisely certain interpulse interval in an input pulse sequence. If the total synaptic potentials excess a threshold, the model generates output spike, which changes weight of all spines according to the simplified Hebb principle. The model was trained by real firing caused in the auditory nuclei of the frog by tones modulated by low-frequency noise in the frequency ranges of 0–15 Hz, 0–50 Hz or 0–150 Hz. After that training the synaptic weights of every spine essentially changed. Thus, along with some increase of weights of spines tuned to boundary frequencies of modulating noise, the most characteristic change was the emphasizing weights of spines tuned to short interpulse intervals. As a result the spontaneous activity passed through the trained model became much more bursting. Efficiency of a signal transmission in model was higher when input spontaneous activity of real cells contains bursts of spikes. Results of modeling are discussed in connection with modern physiological data demonstrating the functional advantage of bursting.     

Formation of Three New Trisaccharide-azoxyglycosides by Transglucosylation by Cycad β-Glucosidase

transglucosylation by a β-d-glucosidase from cycad seeds. These azoxyglycosides, named neocycasin H, I, and J, were identified as O-β-d-glucopyranosyl-(1→4)-O-β-d-glucopyranosyl-(l→3)-O-β-d-glucopyranoside of methylazoxymethanol (MAM), O-β-d-glucopyranosyl-(1→3)-[O-β-d-glucopyranosyl-(1→6)]-O-β-d-glucopyranoside of MAM, and O-β-d-glucopyranosyl-(1→3)-[O-β-d-xylopyranosyl-(1→6)]-O-β-d-glucopyranoside of MAM, respectively. On the basis of their structures, the mechanism of the formation of these neocycasins is also discussed.     

BAFfled by Poxviruses?

Successful viruses engage in a dynamic interplay with their hosts, where both utilize diverse strategies to impose their supremacy. In this issue of Cell Host & Microbe, Wiebe and Traktman describe a novel interaction between vaccinia virus and mammalian cells. A host protein called BAF can bind ectopic cytoplasmic DNA and block viral DNA replication, whereas vaccinia in turn counteracts this inhibition with a virus-encoded serine threonine kinase that inactivates BAF.     

Inactivation of dopamine β-monooxygenase by hydrogen peroxide and by ascorbate

The inactivation of the water-soluble form of bovine adrenal dopamine β-monooxygenase by H₂O₂ and by ascorbate was studied. Inactivation by H₂O₂ was slow for the copper-free apoenzyme, but addition of copper gave a rapid inactivation. The results presented indicate that the enzyme-bound copper during this inactivation catalyzes partial destruction of its own binding site. The reaction orders for the inactivation by H₂O₂ seem to be 1.0 with respect to the enzyme and in the range 0.6 to 0.8 with respect to H₂O₂. The rate of inactivation obtained in the presence of ascorbate increases with addition of copper and is faster than that obtained by similar concentrations of H₂O₂. The data could not, however, be used to decide whether the inactivation by ascorbate was catalyzed by the enzymebound copper. The inactivation reaction in the presence of ascorbate seems to be of first order with respect to ascorbate at ascorbate concentrations less than 40 μm and decreases toward zero as the ascorbate concentration is increased. Experiments with the Cu(I)-chelator, bathocuproine disulfonate, revealed that inactivation led to weaker binding of copper to the protein, and this effect was more pronounced with H₂O₂ than with ascorbate.     

Vanadium Uptake by Alfalfa Grown in V–Cd-Contaminated Soil by Pot Experiment

In order to characterize uptake of vanadium in alfalfa grown in vanadium–cadmium (Cd)-contaminated soil, 104 soil samples and 94 plant samples were collected from pot experiment. The results showed alfalfa had strong metal adaptability (up to 400 mg kg⁻¹) and high accumulation (up to 3,440.14 mg kg⁻¹) of vanadium. Root had higher contents and better absorption to vanadium than overground part. Moreover, both root and overground part had direct correlation with vanadium in soil, especially with the sum of first three fractions and reducible fraction. With the increasing of vanadium, higher concentration of Cd may inhibit the absorption of vanadium in alfalfa.     

Weak protein–protein interactions revealed by immiscible filtration assisted by surface tension

Biological mechanisms are often mediated by transient interactions between multiple proteins. The isolation of intact protein complexes is essential to understanding biochemical processes and an important prerequisite for identifying new drug targets and biomarkers. However, low-affinity interactions are often difficult to detect. Here, we use a newly described method called immiscible filtration assisted by surface tension (IFAST) to isolate proteins under defined binding conditions. This method, which gives a near-instantaneous isolation, enables significantly higher recovery of transient complexes compared to current wash-based protocols, which require reequilibration at each of several wash steps, resulting in protein loss. The method moves proteins, or protein complexes, captured on a solid phase through one or more immiscible-phase barriers that efficiently exclude the passage of nonspecific material in a single operation. We use a previously described polyol-responsive monoclonal antibody to investigate the potential of this new method to study protein binding. In addition, difficult-to-isolate complexes involving the biologically and clinically important Wnt signaling pathway were isolated. We anticipate that this simple, rapid method to isolate intact, transient complexes will enable the discoveries of new signaling pathways, biomarkers, and drug targets.     

Enzyme kinetics by mid-infrared spectroscopy: β-fructosidase study by a one-step assay

An alternate method for enzyme study is proposed. Multidimensional statistical analysis applied on mid-infrared attenuated total reflectance spectra (Cadet et al. (1991) Appl. Spectrosc. 42, 166–172) collected during a kinetic allows a direct and fast quantification of the remaining substrate, as well as a one step enzymatic assay. Furthermore, the combination of these techniques may be used as a structural tool. The method applied to the study of β-fructosidase is developed in this paper as an example. With appropriate calibration, the method may be extend to any enzyme.