Haplorhini

The two contrasting theoretical approaches to visual perception, the constructivist and the ecological, are briefly presented and illustrated through their analyses of space and size perception. Earlier calls for their reconciliation and unification are reviewed. Neurophysiological, neuropsychological, and psychophysical evidence for the existence of two quite distinct visual systems, the ventral and the dorsal, is presented. These two perceptual systems differ in their functions; the ventral system's central function is that of identification, while the dorsal system is mainly engaged in the visual control of motor behavior. The strong parallels between the ecological approach and the functioning of the dorsal system, and between the constructivist approach and the functioning of the ventral system are noted. It is also shown that the experimental paradigms used by the proponents of these two approaches match the functions of the respective visual systems. A dual-process approa...

Aggressiveness is an ancestral behavior common to all animal species. Its neurophysiological mechanisms are similar in all vertebrates. Males are generally more aggressive than females. In this review, aggressive behavior in rodents, monkeys, and man and the role of testosterone and brain serotonin levels have been considered. Interspecific aggressiveness in rats has been studied considering the mouse-killing behavior; the neonatal androgenization of females increases adult mouse-killing as does the administration of testosterone in adults. Intraspecific aggressiveness was studied by putting two or more male rats (or mice) in the same cage; the condition of subjection or dominance is influenced by testosterone. In monkeys, testosterone is related to aggressiveness and dominance and, during the mating season, increases in testosterone levels and aggressive attitude are observed. In men, higher testosterone levels were obtained in perpetrators of violent crimes, in men from the army w...

The rotavirus capsid is composed of three concentric protein layers. Proteins VP4 and VP7 comprise the outer layer. VP4 forms spikes, is the viral attachment protein, and is cleaved by trypsin into VP8* and VP5*. VP7 is a glycoprotein and the major constituent of the outer protein layer. Both VP4 and VP7 induce neutralizing and protective antibodies. To gain insight into the virus neutralization mechanisms, the effects of neutralizing monoclonal antibodies (MAbs) directed against VP8*, VP5*, and VP7 on the decapsidation process of purified OSU and RRV virions were studied. Changes in virion size were followed in real time by 90° light scattering. The transition from triple-layered particles to double-layered particles induced by controlled low calcium concentrations was completely inhibited by anti-VP7 MAbs but not by anti-VP8* or anti-VP5* MAbs. The inhibitory effect of the MAb directed against VP7 was concentration dependent and was abolished by papain digestion of virus-bound ant...

Much more than other primates, man has several features that are seen more often in aquatic than terrestrial mammals: nakedness, thick subcutaneous fat-layer, stretched hindlimbs, voluntary respiration, dilute urine etc. The Aquatic Ape Theory states that our ancestors once spent a significant part of their life in water. Presumably, early apes were plant and fruit eaters in tropical forests. Early hominids also ate aquatic food; at first mainly weeds and tubers, later sea shore animals, especially shellfish. With the Pleistocene cooling, our ancestors returned to land and became bipedal omnivores and scavengers and later hunters of coastal and riverside animals.

Adaptive decision-making uses information gained when exploring alternative options to decide whether to update the current choice strategy. Magnocellular mediodorsal thalamus (MDmc) supports adaptive decision-making, but its causal contribution is not well understood. Monkeys with excitotoxic MDmc damage were tested on probabilistic three-choice decision-making tasks. They could learn and track the changing values in object-reward associations, but they were severely impaired at updating choices after reversals in reward contingencies or when there were multiple options associated with reward. These deficits were not caused by perseveration or insensitivity to negative feedback though. Instead, monkeys with MDmc lesions exhibited an inability to use reward to promote choice repetition after switching to an alternative option due to a diminished influence of recent past choices and the last outcome to guide future behavior. Together, these data suggest MDmc allows for the rapid disc...

Stereopsis is a process by which the visual system gauges the relative depth of objects in three-dimensional space by measuring minute positional differences between left and right images. According to the standard notion, this information is thought to be encoded in the primary visual cortex by differences in receptive field (RF) positions for the two eyes. We have developed in alternative model by which stereoscopic information is coded and transformed through a hierarchical chain of processing in the primary visual cortex. Initially, first-order neurons of the visual cortex, simple cells, encode depth information by a scheme based on differences in internal receptive field structure between left and right eyes. Further abstraction of information is achieved by a subset of second-order neurons, complex cells, that are well suited for the detection of depth information in a manner unaffected by positional variations of objects. We review physiological evidence from studies of the c...

A triple association has been observed between a high negative surface charge, bone morphogenetic activity, and in vitro recalcificaiton in implants of demineralized bone matrix. Proplast fills with bony tissue when implanted in the body and shows the same triple association. The higher the negative surface charge, the greater is the mass of new bone induced and the higher degree of mineralization when placed in a calcifying solution in vitro. Further investigations are necessary to determine whether in implants of demineralized bone, a high negative surface charge may cause the formation of discrete calcium deposits or whether it triggers the invading primitive cells to differnetiate and produce bone, or both.

Polyethylenimine (PEI) is a cationic DNA condensing polymer that facilitates gene transfer into the mammalian cells. The highest gene transfer with branched PEI is obtained at high nitrogen/phosphate (N/P) ratios with free PEI present. The small molecular weight PEI alone is not able to mediate DNA transfection. Here, we used recently developed time-resolved fluorescence spectroscopic method to study the mechanism of PEI-DNA complex formation and to investigate how free PEI, mean molecular weight, and branching of PEI affect the complexes. Analysis of fluorescence lifetimes and time-resolved spectra revealed that for both linear and branched high-molecular-weight PEI the complexation takes place in two steps, but the small-molecular-weight branched PEI complexed DNA at a single step. According to the binding constants obtained from time-resolved spectroscopic measurements, the affinity of N/P complexation per nitrogen atom is highest for LPEI and weakest for BPEI, whereas SPEI-DNA complexation showed intermediate values. Thus, the binding constant alone does not give adequate measure for transfection efficiency. On the other hand, the presence of intermediate states during the polyplex formation seems to be favorable for the gene transfection. Free PEI had no impact on the physical state of PEI-DNA complexes, even though it was essential for gene transfection in the cell culture. In conclusion, the molecular size and topology of PEI have direct influence on the DNA complexation but the free PEI does not. Free PEI must facilitate transfection at the cellular level and not via indirect effects on the PEI-DNA complexes.

Neuroscience seems like such an established field that it may surprise readers to learn that it (as distinct from neurophysiology and neuroanatomy as separate disciplines) was established only in 1962, with the founding of the Neurosciences Research Program (NRP) at the Massachusetts Institute of Technology (MIT) by Francis O. Schmitt and a variety of scientists interested in the neural basis of behavior and mind. (The Society for Neuroscience was founded in 1969 with Ralph W. Gerard as Honorary President.) The NRP hosted four summer schools and multiple Work Sessions over the next 20 years to help establish the new field. Schmitt not only brought together a variety of brain-centered disciplines but also championed the application of molecular biology and genetics to the study of the brain. For a history of the NRP, see the essay by George Adelman (2010) who was for many years librarian—and more—for the NRP. Eric Lenneberg published Biological Foundations of Language in 1967. Five y...

The two contrasting theoretical approaches to visual perception, the constructivist and the ecological, are briefly presented and illustrated through their analyses of space and size perception. Earlier calls for their reconciliation and unification are reviewed. Neurophysiological, neuropsychological, and psychophysical evidence for the existence of two quite distinct visual systems, the ventral and the dorsal, is presented. These two perceptual systems differ in their functions; the ventral system's central function is that of identification, while the dorsal system is mainly engaged in the visual control of motor behavior. The strong parallels between the ecological approach and the functioning of the dorsal system, and between the constructivist approach and the functioning of the ventral system are noted. It is also shown that the experimental paradigms used by the proponents of these two approaches match the functions of the respective visual systems. A dual-process approa...

The hemagglutinin (HA) of influenza virus is a type I transmembrane glycoprotein which is acylated with long-chain fatty acids. In this study we have used oligonucleotide-directed mutagenesis of cloned cDNA and a simian virus 40 expression system to determine the fatty acid binding site in HA and to examine possible functions of covalently linked fatty acids. The results show that the HA is acylated through thioester linkages at three highly conserved cysteine residues located in the cytoplasmic domain and at the carboxy-terminal end of the transmembrane region, whereas a cysteine located in the middle of the membrane-spanning domain is not acylated. Mutants lacking fatty acids at individual or all three attachment sites acquire endoglycosidase H-resistant oligosaccharide side chains, are cleaved into HA1 and HA2 subunits, and are transported to the plasma membrane at rates similar to that of wild-type HA. All mutants are membrane bound and not secreted into the medium. These result...

Mammalian tissues contain at least two types of cannabinoid receptor, CB1 and CB2, both coupled to G proteins. CB1 receptors are expressed mainly by neurones of the central and peripheral nervous system whereas CB2 receptors occur centrally and peripherally in certain non-neuronal tissues, particularly in immune cells. The existence of endogenous ligands for cannabinoid receptors has also been demonstrated. The

Screening of a panel of purified compounds isolated from Aglaia sp. (Meliaceae) for inhibition of early steps in the lentiviral replication cycle led to the identification of the 3, 4-secodammarane triterpenoid, ignT1, which inhibited HIV-1 infection potently (IC(50)=0.48microg/ml), while cytotoxic effects and inhibition of cell proliferation were only observed at concentrations exceeding 10.69microg/ml. Time of addition experiments revealed similar kinetics to the non-nucleoside RT-inhibitor (NNRTI), Nevirapine, although the latter was significantly less cytotoxic. However, unlike Nevirapine, dammarenolic acid also potently inhibited the in vitro replication of other retroviruses, including Simian immunodeficiency virus and Murine leukemic virus in vector-based antiviral screening studies. Interestingly, the methyl ester analogue of dammarenolic acid-methyldammarenolate had no anti-HIV-1 activity. Cell cycle analysis revealed that ignT1 arrests HeLa cells at the S and G2/M phase. T...

The presence of Papio cynocephalus, Cercopithecus mitis, Cercopithecus aethiops and Colobus angolensis in a small coastal forest is attributed to their differential habitat utilization. Data on diet, space-use patterns and polyspecific associations are given. Habitat partitioning is found to be resource-related and is accomplished through differential reliance on resources as well as different means of exploiting overlapping resources. The implications of the data for understanding the relationship between ecology and social structure are discussed.