Colour vision in the passeriform bird,Leiothrix lutea: correlation of visual pigment absorbance and oil droplet transmission with spectral sensitivity

The visual receptors in the retina of the passeriform bird Leiothrix lutea were examined microspectro-photometrically. The rods had a maximum absorbance close to 500 nm. Four spectrally different classes of single cone were identified with typical combinations of photopigments and oil droplets: a long-wave sensitive cone with a photopigment P568 and a droplet with a cut-off wavelength at 564 nm, a middle-wave sensitive cone with a P499 and a droplet with a cut-off at 506 nm, a short-wave sensitive cone with a P454 and a droplet with maximum absorbance below 410nm and an ultraviolet sensitive cone with a P355 and a transparent droplet. Double cones possessed a P568 in both the principal and accessory members. A pale droplet with variable absorbance (maximal at about 420 nm) was associated with the principal member whereas the ellipsoid region of the accessory member contained only low concentrations of carotenoid. The effective spectral sensitivities of the different cone classes were calculated from the characteristic combinations of oil droplets and photopigments and corrected for the absorbance of the ocular media. Comparison of these results with the behavioural spectral sensitivity function of Leiothrix lutea suggests that the increment threshold photopic spectral sensitivity of this avian species is mediated by the 4 single cone classes modified by neural opponent mechanisms.Abbreviations LWS long wave sensitive - MWS middle wave sensitive - SWS short wave sensitive (cones)     

Repetitive mating and female fitness in Dysdercus cardinalis (Hemiptera: Pyrrhocoridae)

Using three mating-treatment groups–pairing with a male for life, pairing with a male from adult emergence to first oviposition, and no pairing (virgin)–of Dysdercus cardinalis females in a laboratory study, the following results were obtained. Most of the virgin females did not lay eggs; those that did oviposited for the first time at a considerably older age than females in the other two groups. In a lifetime, females pairing with a male for life and those pairing with a male up to first oviposition produced essentially the same number of eggs, and this was more than 3.5 times the number of eggs laid by a virgin female. Virgin females produced an average of 1.3 clutches in a lifetime, compared with about 4.5 clutches produced by females in the other two groups. Reproductive span was significantly shorter, and fecundity per day of reproductive span significantly greater, for females pairing with males for life than for those pairing with a male up to first oviposition. Age at death was significantly different amongst females in different mating-treatment groups. Virgin females had the longest life, followed by females pairing with a male up to first oviposition and females pairing with a male for life, in that order. There was a positive correlation between lifetime gross reproduction and age at death for females pairing with a male for life. There was no relationship between these two characters for females pairing with a male up to first oviposition. Both females pairing with a male for life and those pairing with a male to first oviposition exhibited a significant inverse relationship between fecundity per day and age at death. The results obtained indicate that (1) mating is a prerequisite for normal gonadal activity in Dysdercus cardinalis , and (2) repetitive mating increases the rate of reproduction. This would reduce the mean age of parenthood which is inversely related to the intrinsic rate of increase.     

Do rats represent time logarithmically or linearly?

This study examined two possible psychophysical time scales, a logarithmic representation of time with constant variability and a linear representation of time with scalar variability. Twenty-four rats were tested on a modified temporal bisection procedure in which multiple responses could occur in a 10-s time window after the termination of a stimulus. The number of “long” or “short” responses was used as a measure of the rats’ certainty of the duration of the presented interval. Data were analyzed with signal detection theory, and straight lines were fit to the zROC curves with the assumptions of a logarithmic representation of time with constant variability and a linear representation of time with scalar variability. The logarithmic representation of time with constant variability provided a better fit to the data than the linear representation of time with scalar variability.     

Effects of initial-link duration on preference and resistance to change in concurrent-chains schedules

Previous studies with concurrent-chains procedures have shown that preference for a terminal-link signaling a higher reinforcement rate decreases as initial-link durations increase. Using a concurrent-chains procedure, the present experiment examined the effects of manipulating initial-link duration on preference and resistance to disruption with rats nose poking for different rates of food reinforcement in the terminal links. Consistent with previous findings, preference for a terminal link with a higher reinforcement rate decreased with longer initial links. Conversely, relative resistance to disruption in the terminal link with a higher reinforcement rate increased with longer initial links. These findings are counter to the prediction of behavioral momentum theory that preference and resistance to change should be positively related.     

Somatostatin release in the hippocampus in the kindling model of epilepsy: a microdialysis study

Somatostatin biosynthesis in the hippocampus is activated during and following kindling epileptogenesis. The aim of this study was to investigate whether this phenomenon is associated with enhanced somatostatin release in vivo. Experiments have been run in awake, freely moving rats, implanted with a bipolar electrode in the right amygdala (for kindling stimulation), and with a recording electrode and a microdialysis probe in the left hippocampus. Basal somatostatin-like immunoreactivity (-LI) release was significantly greater in kindled than naive rats. In naive rats, a 2-min perfusion with 100 mM K(+) did not affect behavior and EEG recordings and nonsignificantly increased somatostatin-LI release; a 10-min K(+) perfusion evoked numerous wet dog shakes, electrical seizures (class 0; latency congruent with 8 min, duration congruent with 8 min), and somatostatin-LI release ( congruent with 350% of basal); and a single kindling after-discharge (4 +/- 3-s duration in the hippocampus) also evoked somatostatin-LI release ( congruent with 200% of basal). In kindled rats, a 2-min 100 mM K(+) perfusion evoked hippocampal discharges in three of seven animals (latency congruent with 2 min, mean duration congruent with 1.5 min) and increased somatostatin-LI release ( congruent with 250% of basal); a 10-min K(+) perfusion evoked behavioral seizures (class 1 to 5, latency congruent with 4 min, mean duration congruent with 12 min) with numerous wet dog shakes and robust somatostatin-LI release ( congruent with 350% of basal); and a kindling stimulation evoked generalized seizures (class 4 or 5, 77 +/- 15-s duration in the hippocampus) with remarkable somatostatin-LI release ( congruent with 300% of basal). These data demonstrate that hippocampal somatostatin release is increased in the kindling model in vivo.     

On the interactions of catalase with subcellular structure

The interaction of mouse liver catalase with subcellular membranes was studied, and an ionic interaction with a variety of membranes, including those derived from the microsomes, was observed. The interaction with microsomal membranes was found to be abolished by pre-treatment of catalase with neuraminidase, indicating a functional significance for catalase-bound sialic acid. Catalase activity was found to be enhanced when bound to membranes, and evidence for a weak association of catalase with peroxisomal structure in mouse liver was also obtained. It is concluded that mouse liver catalase has a capacity to bind to a variety of subcellular membranes in vivo and that this interaction may be consistent with a general protective role for the enzyme, as well as being compatible with a model of peroxisomal biogenesis which involves the interaction of catalase with microsomal membranes.Abbreviations LGF Large Granule Fraction     

Pro-apoptotic protein kinase C delta is associated with intranuclear inclusions in a transgenic model of Huntington's disease

In order to investigate any effect of truncated mutant huntingtin (tNhtt) aggregation on protein kinase C (PKC) signaling in Huntington's disease (HD), we studied a possible association of PKC isoforms with the aggregates using cellular and transgenic models of HD. In this report we describe an association of mutant tNhtt with at least three PKC isoforms (alpha, delta, zeta), as revealed by co-immunoprecipitation assays and immunocytochemistry in a cellular model of HD (Neuro2a cells expressing tNhtt-150Q-EGFP), as well as a specific association of PKC delta with intranuclear aggregates in a transgenic model (R6/2 mice). Immunoblot analysis of isolated nuclear fractions shows an elevation of nuclear PKC delta in transgenic brain tissue. The observed elevation has a strong similarity with the apoptotic translocation of PKC delta detected in experiments with the mouse neuroblastoma Neuro2a cells. Using a Neuro2a cell line expressing tNhtt with the nuclear localization signal, we demonstrate the association of PKC delta with intranuclear aggregates and present evidence that accumulation of PKC delta in cell nuclei does not depend on mutant htt nuclear translocation. Our results suggest that the association of PKC delta with intranuclear htt-aggregates may affect its apoptotic function in a transgenic model of HD.     

Digit ratio (2D:4D) and the spatial representation of magnitude

Digit ratio (as a putative indicator of prenatal androgen exposure) is related to a range of sexually dimorphic abilities, including spatial skills and mathematical ability. This study examined a phenomenon known as the SNARC effect (Spatial Numerical Association of Response Codes), which is taken as evidence of a mental representation of magnitude along a left-right-oriented number line, with low magnitudes associated with the left side of space, and high numbers with the right side of space. Participants made a parity judgement of numbers with responses made with a left key to odd numbers and a right key to even numbers. This was reversed for a second block of trials. Response times to numbers one to nine with both the right and left hand were calculated, and regression analyses conducted to analyse whether lower magnitudes were responded to faster with the left hand and higher magnitudes with the right hand. Participants with lower (more masculine) digit ratios on the right hand showed a stronger SNARC effect compared to participants with high digit ratios. This pattern of results was also found when the analyses were conducted separately for men and women. Results from left hand digit ratios indicated that only low digit ratio females showed a significant SNARC effect. These findings add to a growing literature on the relationship between digit ratio and cognitive abilities; in this case, simple cognitive representations that are accessed automatically rather than complex skills such as mental rotation or "mathematics" where a variety of solution strategies may be utilised.     

Testes size, ejaculate quality and sperm competition in birds

The relationship between testes size, ejaculate quality (volume, sperm concentration, number of sperm per ejaculate) and sperm competition in birds was analysed using data collected in artificial insemination studies. I hypothesized that ejaculate quality, because of natural selection, should be superior in species with intense sperm competition compared with other species. In regression analyses, testes weight increased with body weight, with an exponent less than one, and ejaculate volume increased with testes weight with an exponent not significantly different from one, whereas sperm number per ejaculate increased with testes weight with an exponent larger than one. Species with relatively large testes also produced ejaculates with a high sperm concentration. Monogamous species with a relatively low intensity of sperm competition copulate rarely, but deliver ejaculates with a relatively large number of sperm. Monogamous species with a high intensity of sperm competition copulate frequently, but produce ejaculates with a relatively small number of sperm. Males of polygynous species, which also experience intense sperm competition, copulate rarely with specific females, but produce many ejaculates per male each with a relatively small number of sperm.     

Reduced birth intervals following the birth of children with long-term illness: evidence supporting a conditional evolved response

Human birth interval length is indicative of the level of parental investment that a child will receive: a short interval following birth means that parental resources must be split with a younger sibling during a period when the older sibling remains highly dependent on their parents. From a life-history theoretical perspective, it is likely that there are evolved mechanisms that serve to maximize fitness depending on context. One context that would be expected to result in short birth intervals, and lowered parental investment, is after a child with low expected fitness is born. Here, data drawn from a longitudinal British birth cohort study were used to test whether birth intervals were shorter following the birth of a child with a long-term health problem. Data on the timing of 4543 births were analysed using discrete-time event history analysis. The results were consistent with the hypothesis: birth intervals were shorter following the birth of a child diagnosed by a medical professional with a severe but non-fatal medical condition. Covariates in the analysis were also significantly associated with birth interval length: births of twins or multiple births, and relationship break-up were associated with significantly longer birth intervals.     

Coexistence of Multiple Periodic and Chaotic Regimes in Biochemical Oscillations with Phase Shifts

The numerical study of a glycolytic model formed by a system of three delay differential equations reveals a multiplicity of stable coexisting states: birhythmicity, trirhythmicity, hard excitation and quasiperiodic with chaotic regimes. For different initial functions in the phase space one may observe the coexistence of two different quasiperiodic motions, the existence of a stable steady state with a stable torus, and the existence of a strange attractor with different stable regimes (chaos with torus, chaos with bursting motion, and chaos with different periodic regimes). For a single range of the control parameter values our system may exhibit different bifurcation diagrams: in one case a Feigenbaum route to chaos coexists with a finite number of successive periodic bifurcations, in other conditions it is possible to observe the coexistence of two quasiperiodicity routes to chaos. These studies were obtained both at constant input flux and under forcing conditions.     

Purification and regulation of aspartate transcarbamylase from germinated mung bean (Vigna radiata) seedlings

Aspartate transcarbamylase (EC 2.1.3.2) was purified to homogeniety from germinated mung bean seedlings by treatment with carbamyl phosphate. The purified enzyme was a hexamer with a subunit molecular weight of 20,600. The enzyme exhibited multiple activity bands on Polyacrylamide gel electrophoresis, which could be altered by treatment with carbamyl phosphate or UMP indicating that the enzyme was probably undergoing reversible association or dissociation in the presence of these effectors. The carbamyl phosphate stabilized enzyme did not exhibit positive homotropic interactions with carbamyl phosphate and hysteresis. The enzyme which had not been exposed to carbamyl phosphate showed a decrease in specific activity with a change in the concentration of both carbamyl phosphate and protein. The carbamyl phosphate saturation and UMP inhibition patterns were complex with a maximum and a plateau region. The partially purified enzyme also exhibited hysteresis and the hysteretic response, a function of protein concentration, was abolished by preincubation with carbamyl phosphate and enhanced by preincubation with UMP. All these observations are compatible with a postulation that the enzyme activity may be regulated by slow reversible association-dissociation dependent on the interaction with allosteric ligands     

On the mechanism of non-endosomial peptide-mediated cellular delivery of nucleic acids

Recently, we described a new strategy for the delivery of nucleic acids into mammalian cells, based on an amphipathic peptide of 27 residues called MPG, which was designed on the basis of a hydrophobic domain derived from a fusion sequence associated with a nuclear localization sequence and separated by a linker. This peptide carrier constitutes a powerful tool for the delivery of nucleic acids in cultured cells, without requiring any covalent coupling. We have examined the conformational states of MPG in its free form and complexed with a cargo, as well as its ability to interact with phospholipids, and have investigated the structural consequences of these interactions. In spite of its similarity to the similarly designed cell-penetrating peptide Pep-1, MPG behaves significantly differently from the conformational point of view. Circular dichroism (CD) analysis reveals a transition from a nonstructured to a β-sheet conformation upon interaction with phospholipids. We propose that the membrane crossing process involves formation of a transient transmembrane pore-like structure. Partial conformational change of MPG is associated with formation of a complex with its cargo, and an increase in sheet content occurs upon association with the cell membrane.     

Prediction of protein domain boundaries from sequence alone

We present here a simple approach to identify domain boundaries in proteins of an unknown three-dimensional structure. Our method is based on the hypothesis that a high-side chain entropy of a region in a protein chain must be compensated by a high-residue interaction energy within the region, which could correlate with a well-structured part of the globule, that is, with a domain unit. For protein domains, this means that the domain boundary is conditioned by amino acid residues with a small value of side chain entropy, which correlates with the side chain size. On the one hand, relatively high Ala and Gly content on the domain boundary results in high conformational entropy of the backbone chain between the domains. On the other hand, the presence of Pro residues leads to the formation of hinges for a relative orientation of domains. The method was applied to 646 proteins with two contiguous domains extracted from the SCOP database with a success rate of 63%. We also report the prediction of domain boundaries for CASP5 targets obtained with the same method.     

Electrophysiological and Pharmacological Analysis of Neuronal Activity in the Midbrain Medial Raphe Nucleus after Acute Immobilization Stress

In albino rats anesthetized with urethane, most medial raphe neurons are characterized by a low rate of the discharges. Acute immobilization stress resulted in a significant enhancement in the number of regularly discharging neurons. After immobilization, the number of neurons with a low-rate impulsation decreased, while the number of neurons with intensive firing increased. Treatment with fluoxetine enhanced the number of regularly firing neurons more than three times, and a predominant part of the neurons demonstrated a high level of background activity. It should be supposed that a significant part of the neurons with high-rate discharges are serotonergic, because their number also increased after fluoxetine administration.     

Fine Needle Aspiration Cytology of High Grade T-Cell Lymphomas In Human T-Lymphotropic Virus Type 1 Carriers

We studied the fine needle aspiration (FNA) cytology of high grade peripheral T-cell lymphomas from eight human T-lymphotropic virus-1 (HTLV-1) positive patients. FNA smears from seven lymphomas showed a distinctive cytologic pattern with a dominance of rounded cells with irregular nuclei and a moderately basophilic cytoplasm. Irregular cells with a pale abundant cytoplasm were present in varying amounts. Some smears contained a few giant cells with cerebriform nuclei. In addition, plasma cells and eosinophils were found. Epithelioid cells were an inconstant finding. On histology these seven lymphomas were assigned to the pleomorphic medium-large cell subtype and all but one were of T-helper phenotype with rearrangements of the T-cell receptor. FNA smears from a lymph node in a patient with a previous histological diagnosis of lymphomatoid papulosis of the gingiva showed a monotonous pattern of large immunoblastic cells with some binucleated variants consistent with a diagnosis of high grade immunoblastic lymphoma, which was confirmed histologically. Our results show that peripheral T-cell lymphomas from HTLV-1 positive patients have cytological patterns which are distinctive enough to allow a conclusive diagnosis of high grade T-cell lymphoma. However, we do not think that the cytology of HTLV-1 positive lymphomas can be differentiated from that of virus-unrelated high grade T-cell lymphomas.     

A novel method to screen genomic libraries that combines genomic immunization with the prime-boost strategy

We employed a prime-boost regimen in combination with the expression library immunization protocol to improve the protective effectiveness of a genomic library used as immunogen. To demonstrate the feasibility of this novel strategy, we used as a prime a serogroup B Neisseria meningitidis random genomic library constructed in a eukaryotic expression vector. Mice immunized with different fractions of this library and boosted with a single dose of meningococcal outer membrane vesicles elicited higher bactericidal antibody titers compared with mice primed with the empty vector. After the boost, passive administration of sera from mice primed with two of these fractions significantly reduced the number of viable bacteria in the blood of infant rats challenged with live N. meningitidis. The method proposed could be applied to the identification of subimmunogenic antigens during vaccine candidate screening by employing expression library immunization.     

Carnitine-acyltransferase activity of mitochondria from mung-bean hypocotyls

Carnitine-acyltransferase activity assayed with acetyl-CoA, octanoyl-CoA, or palmitoyl-CoA is associated with the mitochondrial but not with the peroxisomes of mung-bean hypocotyls. Using mitochondria as an enzyme source, a half-maximal reaction rate is obtained with a palmitoyl-CoA concentration approximately twice that required with acetyl-CoA. In the presence of a saturating acetyl-CoA concentration the carnitine-acyltransferase activity is not enhanced by palmitoyl-CoA as additional substrate. However, palmitoylcarnitine is formed in addition to acetylcarnitine, and the formation of acetylcarnitine is competitively inhibited by palmitoyl-CoA. It is concluded that the mitochondria of mung-bean hypocotyls possess a carnitine acyltransferase of broad substrate specificity with respect to the chainlength of the acyl-CoA and that the demonstration of a carnitine-palmitoyltransferase activity in plant mitochondria does not indicate the presence of a specific carnitine long-chain acyltransferase.     

Nonverbal Communication and Human–Dog Interaction

Human–dog interaction relies to a large extent on nonverbal communication, and it is therefore plausible that human sensitivity to nonverbal signals affects interactions between human and dog. Experience with dogs is also likely to influence human–dog interactions, and it has been suggested that it influences human social skills. The present study investigated possible links between human nonverbal sensitivity, experience with dogs, and the quality of human–dog interactions. Two studies are reported. In study 1, 97 veterinary students took a psychometric test assessing human nonverbal sensitivity and answered a questionnaire on their experience with dogs. The data obtained were then used to investigate the relationship between experience with dogs and sensitivity to human nonverbal communication. The results did not indicate that experience with dogs improves human nonverbal sensitivity. In study 2, 16 students with high, and 15 students with low, levels of human nonverbal sensitivity were selected. Each of the 31 students interacted once with an unknown dog in a greeting situation, and these human–dog interactions were videoed. We found that a combined score of dog behaviors relating to insecurity was associated with the students' level of nonverbal sensitivity and experience with dogs: the dog showed more of the insecure behavior when interacting with students with a low level of nonverbal sensitivity and no experience with dogs than it did when interacting with students with a high level of nonverbal sensitivity (irrespective of experience with dogs).