Characterization of yeast artificial chromosomes containing interleukin genes on human chromosome 5.

To understand better the organization and linkage of the interleukin genes, IL4 and IL5, we prepared long-range restriction maps of five yeast artificial chromosomes (YACs) containing IL5. We determined that IL4 and IL5 are within 100-170 kb, and that the regions surrounding these genes contain several GC-rich areas. Fluorescence in situ chromosomal analysis demonstrated that three of the five YAC clones contain non-contiguous genomic sequences originating from multiple human chromosomes.     

The development of identified neurosecretory cells in the tobacco hornworm, Manduca sexta

The prothoracicotropic hormone (PTTH) is a principal neuropeptide regulator of insect postembryonic molting and metamorphosis. In the tobacco hornworm, Manduca sexta, PTTH is produced by two neurosecretory cells (NSC) located in each protocerebral lobe of the brain. The development of these neurons, the L-NSC III, has been investigated immunocytologically to establish the time course of their morphological differentiation. PTTH may be one of the earliest neuropeptides expressed in insect embryos. PTTH-immunoreactivity was initially detected in the somata at 24 to 30% of embryonic development. Neurites sprouted shortly thereafter and began to grow medially through the brain anlage. By 42% embryonic development, the neurites had decussated to the contralateral brain lobe. As development progressed, the L-NSC III neurites grew along specific tracts through the contralateral brain lobe reaching the ventrolateral regions of the brain by approximately 60% development. The axons exited the brain through a retrocerebral nerve, the nervi corporis cardiaci I + II. At approximately 63% development, the axons innervated the corpus allatum and began branching to form neurohemal terminals for PTTH release. At 60% development, short collaterals began extending in the protocerebral neuropil. During the remainder of embryogenesis, both the dendritic collaterals and the terminal neurohemal varicosities continued to elongate and arborize. By 85% embryonic development, the basic architecture of the L-NSC III was established.     

Alkaline phosphatase release assay to determine cytotoxicity for Listeria species

A simple cytotoxicity assay for Listeria species was developed by assaying alkaline phosphatase (AP) release from an infected hybrid B lymphocyte (Ped-2E9) line. Eight of eight L. monocytogenes and six of 11 L. ivanovii strains induced significantly high AP release from Ped-2E9 cells compared to five other L. ivanovii strains and other Listeria spp. In contrast, all L. monocytogenes and L. ivanovii test strains showed high release of lactate dehydrogenase (LDH) activity from Ped-2E9 cells. The molecular mass of AP was estimated to be about 128–165 kDa, suggesting severe membrane damage in Ped-2E9 cells due to Listeria infection. The data presented here indicate that AP assay could be used over LDH assay to detect Listeria -induced cell cytotoxicity.     

Perturbations in nucleosome structure from heavy metal association

Heavy metals have the potential to engage in strong bonding interactions and can thus function in essential as well as toxic or therapeutic capacities. We conducted crystallographic analyses of heavy cation binding to the nucleosome core particle and found that Co²⁺ and Ni²⁺ preferentially associate with the DNA major groove, in a sequence- and conformation-dependent manner. Conversely, Rb⁺ and Cs⁺ are found to bind only opportunistically to minor groove elements of the DNA, in particular at narrow AT dinucleotide sites. Furthermore, relative to Mn²⁺ the aggressive coordination of Co²⁺ and Ni²⁺ to guanine bases is observed to induce a shift in histone–DNA register around the nucleosome center by stabilizing DNA stretching over one region accompanied by expulsion of two bases at an opposing location. These ‘softer’ transition metals also associate with multiple histone protein sites, including inter-nucleosomal cross-linking, and display a proclivity for coordination to histidine. Sustained binding and the ability to induce structural perturbations at specific locations in the nucleosome may contribute to genetic and epigenetic mechanisms of carcinogenesis mediated by Co²⁺ and Ni²⁺.     

Identification of calcium-binding proteins associated with the human sperm plasma membrane

Background  

The precise composition of the human sperm plasma membrane, the molecular interactions that define domain specific functions, and the regulation of membrane associated proteins during the capacitation process, still remain to be fully understood. Here, we investigated the repertoire of calcium-regulated proteins associated with the human sperm plasma membrane.     

Dual effects of calcium on the oxidation of fatty acids to ketone bodies in liver mitochondria

The addition of calcium ions (Ca²⁺) to rat liver mitochondria, under conditions of rapid accumulation of 10–40 nmol Ca²⁺/mg protein, inhibited the oxidation of long and medium chain fatty acids to ketone bodies, whereas higher quantities of Ca²⁺ activated the process. The mitochondrial NADH:NAD ratio exhibited corresponding depression and elevation. Both inhibitory and stimulatory actions of Ca²⁺ were operative in liver mitochondria from fed and fasted rats and appear to be localized in the mitochondrial inner membranematrix region. These observations may signify involvement of Ca²⁺ in the regulation of fatty acid oxidation and ketogenesis.     

Somatic cell hybrid mapping of human chromosome band 5q31: a region important to hematopoiesis.

As a means of characterizing the distal long arm of chromosome 5, in particular, the region spanning 5q23-->q31, we analyzed somatic cell hybrids prepared from cells with overlapping chromosomal rearrangements. In one hybrid, the derivative chromosome 5 from a patient with acute myeloid leukemia (AML) de novo, whose bone marrow cells had a balanced translocation, t(5;7)(q31;q22), involving chromosome band 5q31, was isolated in a somatic cell hybrid (B294). In addition, we prepared somatic cell hybrids from a lymphoblastoid cell line (CC) derived from a patient who has a constitutional interstitial deletion of chromosome 5 spanning 5q23.1-->q31.1. By a combination of Southern hybridization analysis and fluorescent in situ hybridization, we constructed a map dividing 5q23-->q31 into four regions. We can assign genes to these regions and relate them to anonymous RFLP markers that have been genetically mapped.     

Three-dimensional architecture of identified cerebral neurosecretory cells in an insect

The organization of identified neurosecretory cell groups in the larval brain of the tobacco hornworm, Manduca sexta, was investigated immunocytologically. Computer-assisted three-dimensional reconstruction was used to examine the architecture of the neurosecretory cell groups. The group III lateral neurosecretory cells (L-NSC-III) which produce the prothoracicotropic hormone are located dorsolaterally in the protocerebrum and extend axons medially that decussate to the contralateral lobe prior to exiting the brain through the nervi corporis cardiaci I + II. The group IIa2 medial neurosecretory cells (M-NSC IIa2) are located anteriorly in the medial dorsal protocerebrum. The axons of these cells also exit the brain via the contralateral nervi corporis cardiaci I + II. However, their axons traverse a different pathway through the brain from that of the L-NSC III axons. Each of the cell groups possesses elaborate dendrites with terminal varicosities. The dendrites can be classified into specific fields based upon their location and projection pattern within the brain. The dendrites for these two neurosecretory cell groups overlap in specific regions of the protocerebral neuropil. After the axons of these neurosecretory cells exit the brain through the retrocerebral nerve, they innervate the corpus allatum where they arborize to form neurohemal terminals in strikingly different patterns. The L-NSC III penetrate throughout the glandular structure and the M-NSC IIa2 terminals are restricted to the external sheath. A third group of cerebral neurosecretory cells, the ventromedial neurons (VM) which stain with the monoclonal antibody to prothoracicotropic hormone in Manduca, are located anteriorly in the medial region of the brain. The axons of these cells do not exit the brain to the retrocerebral complex, but rather pass through the circumesophageal connectives and ventral nerve cord. These neurons appear to be the same VM neurons that produce eclosion hormone. One dendritic field of the L-NSC III terminates in close apposition to the VM neurons. The distinct morphologies of these neurosecretory cell groups in relation to other cell groups and the distribution of neuropeptides within the neurons suggest that insect neurosecretory cells, like their vertebrate counterparts, may have multiple regulatory roles.