Post embryonic development of the central nervous system of the spider Argiope aurantia (Lucas)

Volumetric and histological changes of the central nervous system were studied during post embryonic development of a spider, Argiope aurantia. The neural mass of Argiope grows allometrically with respect to volume of the cephalothorax and body weight. In the first instar 46% of the cephalothoracic volume constitutes the neural mass and this is reduced to 4% in the female (9th stage) and 12% in the male (7th stage) spider. Growth curves for the cephalic ganglion, measured at all stages, represent a straight line. The neural mass of females is two and a half times larger than that of the males. The ganglion increased 24 fold in female and 10 fold in male spiders. Addition of neural mass occurs in all stages. The brain volume is greater than that of the subesophageal ganglion in the first two instars. In subsequent stadia, the subesophageal ganglion grows faster, and in females it is finally three times and in males two times larger than the brain. Growth of cortex and neuropile depict exponential curves. Comparison of growth patterns of these shows an inverse relationship during development. While the volume of the cortex is higher in the first two or three stages, the volume of the neuropile is higher in the remaining stadia. The causes for this growth pattern are discussed. Counts of cell numbers show that there is a constant population of neurons throughout the post-embryonic development. The number of nerve cells in females is higher than in males, 11% in the subesophageal ganglion and 58% in the brain. The growth of the cortex is partly accomplished by an increase in cell volume. In male and female spiders the increase in Type-B cells is 20 and 50 fold, while that of large motor neurons is 200 and 600 fold respectively. The motor neurons of 20 μ and above number 63 in male and 916 in female adult spiders. The growth of neuropile occurs through an increase of dendritic arborization and axonal branching. The largest axons measure 1 μ in the first and 16 μ in adult stages. An increase of incoming sensory fibers is also noticed during development. Invasion of neural lamella into cortex and neuropile increases during development. Neural lamella which are 1-2 μ in the first stage grow to 40–100 μ thickness in adult female spiders, near the origin of the main nerves. One type of astral cells, counted in neuropile, increases 10 fold. The appearance of a central body and the beginning of web construction coincide during the second instar. The relationship between these two is discussed.     

Quantitative studies of superior cervical sympathetic ganglia in a variety of primates including man. II. Neuronal packing density

The volumes of a sample of primate superior cervical sympathetic ganglia were measured and related to body weight and to the number of ganglionic neurons. Estimates of volumes of the ganglia varied between 1.956 mm³ in squirrel monkey and 173.530 mm³ in a human specimen. Average cell densities for the ganglia ranged from 4,455 cells/mm³ in a human ganglion to 32,528 cells/mm³ in a squirrel monkey ganglion. Mean cell territories varied from 0.0000307 mm³ in a squirrel monkey ganglion to 0.0002245 mm³ in a human ganglion. Analysis of the data reveals striking trends of correlation between body size, volume of ganglia, and average cell territories. Since similar correlations have been described for other types of neuronal cell aggregates, it is suggested that for any given nucleus, ganglion or cortical area, the neuronal packing density varies as a function of body size.     

Influence of Ammonium on the Growth and Development of Suspension Cultures of Pauľs Scarlet Rose

In this work as in previous studies from this laboratory it was demonstrated that the presence of a trace amount of NH₄⁺ (72.8 μmol) stimulated the growth of Pau?s Scarlet Rose on a defined medium containing NO₃^? (1920 μmol) as the only other source of nitrogen. A kinetic analysis of several growth parameters showed that the rate of increase of dry weight, fresh weight, cell number, and cell volume were greater during early stages of growth (days 0–8) when NH₄⁺ was provided. During later stages (days 8–14) this relationship between the two cultures did not hold. The cells provided NH₄⁺ continued to increase in fresh weight and cell volume, but the cells which were not provided NH₄⁺ had a greater rate of dry weight and cell number increase. These differences led to 14-day-old cultures which were approximately equal in dry weight and cell number but differed by a factor of 2 in fresh weight. The presence of NH₄⁺ speeded up the development and growth of the cells.     

Experimental studies on parasitization byApanteles Glomeratus V. Relationships between growth rate of parasitoid and host age at the time of oviposition

The growth and development ofApanteles glomeratus L. eggs and larvae in the host larva (Pieris rapae crucivora Boisduval) was investigated by calculating their volume. WhenA. glomeratus eggs increase 90 fold in volume after being laid, larvae hatch from them. The larvae grow exponentially and the growth rate of the parasitoid is dependent on the host stage. Being laid in the 1st instar host, the parasitoids grow more slowly than those laid in 2nd–4th instar host. A pupal host stage prevents the parasitoids’ development. When larvae exceed the threshold size of 5.0×10⁸ μ³, they enter the 2nd instar. A few days after they attain the maximum size of 3.3×10⁹ μ³, they moult and egress from the host body.     

Stereological and allometric studies on neurons and axo-dendritic synapses in the superior cervical ganglia of rats, capybaras and horses

The superior cervical ganglion (SCG) in mammals varies in structure according to developmental age, body size, gender, lateral asymmetry, the size and nuclear content of neurons and the complexity and synaptic coverage of their dendritic trees. In small and medium-sized mammals, neuron number and size increase from birth to adulthood and, in phylogenetic studies, vary with body size. However, recent studies on larger animals suggest that body weight does not, in general, accurately predict neuron number. We have applied design-based stereological tools at the light-microscopic level to assess the volumetric composition of ganglia and to estimate the numbers and sizes of neurons in SCGs from rats, capybaras and horses. Using transmission electron microscopy, we have obtained design-based estimates of the surface coverage of dendrites by postsynaptic apposition zones and model-based estimates of the numbers and sizes of synaptophysin-labelled axo-dendritic synaptic disks. Linear regression analysis of log-transformed data has been undertaken in order to establish the nature of the relationships between numbers and SCG volume (V_scg). For SCGs (five per species), the allometric relationship for neuron number (N) is N=35,067×V_scg^0.781 and that for synapses is N=20,095,000×V_scg^1.328, the former being a good predictor and the latter a poor predictor of synapse number. Our findings thus reveal the nature of SCG growth in terms of its main ingredients (neurons, neuropil, blood vessels) and show that larger mammals have SCG neurons exhibiting more complex arborizations and greater numbers of axo-dendritic synapses.     

Development of neurons in the abdominal ganglion of Aplysia californica. I. Axosomatic synaptic contacts.

The development of mariculture techniques for the raising of Aplysia californica in the laboratory from fertilized egg to reproductively mature adult permits the study of the developmental program whereby individual identified neurons in the abdominal ganglion acquire their specific adult properties. In this paper, we describe one of the early steps of this developmental program: the outgrowth of axonal processes by neurons of the abdominal ganglion. Axonal outgrowth is correlated with and may be triggered by the transient appearance of morphologically identifiable axosomatic contacts between the as yet undifferentiated cell body of specific neurons and an axon terminal from an incoming nerve fiber from the pleuroabdominal connective. The evidence that transient axosomatic contacts may signal neuronal differentiation is the following: (1) Axosomatic contacts have not been observed in the abdominal ganglion of adult animals, whereas they are commonly observed during the early stages of development. (2) Cells that receive axosomatic contacts are undifferentiated morphologically and do not as yet have axons. By contrast, cells with axons do not have soma contacts. (3) Individual cells that can be identified from animal to animal in the same and succeeding developmental stages receive axosomatic contacts on similar topographic postions of the cell body at one point in development. Axon outgrowth then occurs at the site of contact. Later in development, with further axon extension, these cells no longer have synaptic contacts on the cell body or axon.     

Effect of parasitism byAscogaster reticulatus [Hym.: Braconidae] on growth of the host,Adoxophyes sp. [Lep.: Tortricidae]

The developmental interaction between the egg/larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae) and its host,Adoxophyes sp. (Lepidoptera: Tortricidae) was examined. Prior to the egress of a final-instar parasitoid larva from the 4^th-instar host larva, host weight decreased by 22% from the maximum weight. The final body weight of a host larva was 27% of the maximum weight of a healthy 5^th-instar host. Food consumption was significantly reduced in both 3^rd-and 4^th-instar parasitized larvae compared with healthy ones. In the 4^th instar, a parasitized larva consumed 28% less artificial diet and produced less frass than a healthy larva. The growth rate of the endoparasitoid larvae greatly increased after their host's molt to the 4^th instar. Parasitoid larval volume increased 40 fold in the 4^th-instar host.      

Ciliary ganglion neurons in cell culture: high affinity choline uptake and autoradiographic choline labeling

Chick ciliary ganglion neurons grown in dissociated cell culture have a high affinity uptake mechanism for choline that has the properties expected for cholinergic neurons. The uptake has an apparent K_m of ca. 0.3 μM and is blocked by addition of 10 μM hemicholinium-3 or replacement of Na⁺ by Li⁺ in the uptake medium. When the choline uptake mechanism is used to label ciliary ganglion neuron-myotube cultures autoradiographically, over 99% of the neurons are labeled. A few cells with neuronal morphologies in such cultures (<1%) are labeled by γ-[³H]aminobutyric acid uptake. The number of [³H]choline-labeled neurons and the amount of Na⁺-dependent choline uptake is the same for ciliary ganglion neurons grown with and without skeletal myotubes. Rat superior cervical ganglion neurons, grown in cell culture under conditions that induce them to synthesize acetylcholine and form cholinergic synapses, are labeled by [³H]choline uptake, though not as heavily as ciliary ganglion neurons. In contrast, chick dorsal root ganglion neurons, a presumed population of noncholinergic neurons, are not labeled by [³H]choline uptake. Thus high affinity choline uptake can be used to label autoradiographically the cholinergic neurons tested, while at least one population of noncholinergic neurons remains unlabeled.     

Development of neurons in the abdominal ganglion of Aplysia californica. II. Nonneural support cells.

The release by nonneural support cells of a diffusable chemical substance into the local environment in which sympathetic neurons develop is thought to play a crucial role in their differentiation. In this paper, we describe a novel class of nonneural support cells associated with a central ganglion of Aplysia californica during the premetamorphic stages of development. These support cells contain secretory granules whose contents are primarily released at metamorphosis. The release of these contents may signal the burst of neuronal growth and maturation that occurs following metamorphosis. The evidence in support of this notion is the following: (1) Spontaneous release of the granule material at metamorphosis coincides with an increase in cell body growth and a more marked increase in the density of synapses of the abdominal ganglion. (2) Premature release of the granule material before metamorphosis with artificial seawater containing a high concentration of potassium results in a burst in cell body growth and a premature increase in synapse density. (3) Premature release of granule material also results in a precocious increase in the number of spines formed and synaptic contacts received by specific identified cells. Based on the findings in this and the preceding paper, we propose a two-stage model of the developmental program for differentiation of neurons in the abdominal ganglion. First, axosomatic contacts trigger axonal outgrowth. Second, material released from the granules of the support cells stimulates further steps in neuronal differentiation, including cell growth, spine development, and synapse formation.     

Changes in the chemical composition of fat body during the last larval instar of Manduca sexta.

The fat body increases in weight throughout the last larval instar in spite of the loss in total body weight during the wandering and prepupal stages. The protein content of fat body increases dramatically and is greatly responsible for the increase in fat body weight in the wandering and prepupal stages. Lipids do not contribute significantly to the fat body weight gain except during the feeding stage. The amount of total fat body RNA increases until wandering then drops abruptly in the prepupal stage. The total amount of fat body DNA peaks before the onset of wandering and prepupal stages.     

Thyroxine influence on different ion-specific adenosine triphosphatase activities in fat body of Bombyx mori during development

The effects of thyroxine on the activity of different ATPases (Na⁺-K⁺, Ca²⁺, and Mg²⁺) in fat body cells of the silkworm, Bombyx mori, were investigated during different developmental stages. In both sexes the maximum enzyme activity was observed in the fat body cells of day 7 last instar larva (the day before spinning). Na⁺-K⁺, Ca²⁺-, and Mg²⁺-ATPase activity in the fat body markedly declined after pupation and continued to decrease in day 1 adults. Injection of thyroxine (T4) at doses of 1.0 and 2.0 μg/g during fifth instar significantly elevated all ATPase activities in the larval, pupal, and adult stages in both sexes. At a dose of 0.5 μg/g, T4 had no effect on day 2 fifth instar larva, although it increased the ATPase activity at the other stages investigated. A higher dose (3.0 μg/g) caused a significant reduction in enzyme activity in all stages with the exception of day 2 fifth instar larva. Thus, the repression of enzyme activity with the higher dose and the elevation of enzyme activity with the lower dose establish the biphasic nature of T4 action on the ATPase system in fat body cells of the silkworm. Arch. Insect Biochem. Physiol. 37:191–196, 1998. © 1998 Wiley-Liss, Inc.     

Nuclear pore flow rate of ribosomal RNA and chain growth rate of its precursor during oogenesis of Xenopus laevis

The number of ribosomal RNA molecules which are transferred through an average nuclear pore complex per minute into the cytoplasm (nuclear pore flow rate, NPFR) during oocyte growth of Xenopus laevis is estimated. The NPFR calculations are based on determinations of the increase of cytoplasmic rRNA content during defined time intervals and of the total number of pore complexes in the respective oogenesis stages. In the mid-lampbrush stage (500–700 μm oocyte diameter) the NPFR is maximal with 2.62 rRNA molecules/pore/minute. Then it decreases to zero at the end of oogenesis. The nucleocytoplasmic RNA flow rates determined are compared with corresponding values of other cell types. The molecular weight of the rRNA precursor transcribed in the extrachromosomal nucleoli of Xenopus lampbrush stage oocytes is determined by acrylamide gel electrophoresis to be 2.5 × 10⁶ daltons. From the temporal increase of cytoplasmic rRNA (3.8 μg per oocyte in 38 days) and the known number of simultaneously growing precursor molecules in the nucleus the chain growth rate of the 40 S precursor RNA is estimated to be 34 nucleotides per second.     

Ectoprotein kinase activity of the isolated rat adipocyte.

Intact adipocytes exhibit ectoprotein kinase activity as reflected by their ability to catalyze the transfer of the terminal phosphate of (γ-³²P) ATP to histone added to a cell suspension. This activity is substrate, time and cell number dependent. Lineweaver-Burk plots gave Km and Vmax values for ATP of 5 × 10^?5 M and 7.14 pmoles/min/1.5 × 10⁵ cells. Cyclic AMP but not cyclic GMP in μM concentrations stimulates ectoprotein kinase activity. The controlled tryptic digestion of intact cells results in reduction of ectoprotein kinase activity. This activity is not due to leakage of intracellular protein kinases during the preparative procedure nor to penetration of histone into the cells. Additional phosphoproteins not accessible to endogenous protein kinase activity are also localized on the external surface of the intact fat cell.     

A Cytophotometric analysis of the DNA in the nucleus of the giant cell,R-2, in <Emphasis Type="Italic">Aplysia</Emphasis>

DNA was cytophotometrically measured in Feulgen stained nuclei of R-2, the giant neuron of the abdominal ganglion in Aplysia. The data indicate that the nucleus hag a volume of more than 7 X 10⁶ μ³ in large animals, and contains as much as 75000 times the haploid amount of DNA. To our knowledge, this is the most highly polyploid nucleus yet described. Furthermore, the amount of DNA increases with growth, going from approximately 2000 times the haploid amount in small animals to over 75000 times in large animals. The data suggest that the increase in DNA occurs in increments, each increment having approximately twice the DNA as the one before. Thus we suggest that the increase in DNA in the nucleus of R-2 results from the entire genome replicating without accompanying cell division.     

Perinatal changes in avian muscle: Implications from ultrastructure for the development of endothermy

Endothermic heat production and the capacity to shiver develop soon after hatching in birds, permitting chicks to regulate their body temperature. Physiological studies have not clearly identified the developmental events causing this change in function. Here, we use electron microscopy to examine the development of structures involved in muscle activation, contraction, and metabolism coincident with the development of shivering thermogenesis. A stereological study was used to compare the ultrastructure of chicken iliofibularis before endothermic heat production was present (24 h before hatching) and 120 h later, when the iliofibularis had substantial capacity for shivering. Profound increases were found in the t-tubule system and terminal cisternae, mitochondrial cristae, and lipids. The number of triadic profiles increased 3.8-fold (7.6 ± 1.31/100 μm² to 28.5 ± 2.90/100 μm² fiber area). The surface area of cristae per mitochondrial volume doubled (12.0 ± 1.50 pm2/pm3 to 25.7 ± 1.84 μm²/μm³). Lipid droplets were rare in the iliofibularis of embryos about to hatch, but accounted for 4.4% of the muscle fiber volume in day 4 birds. We suggest that these ultrastructural changes more fully activate the iliofibularis, allow it to produce more heat both from calcium pumping and from contraction, and increase its endurance, thus permitting the muscle to be effective in thermogenesis. © 1995 Wiley-Liss, Inc.     

Synthesis of mitochondrial DNA in spermatocytes of Rhynchosciara hollaenderi

During the mid to late 4th instar period of larval development, the mitochondria of Rhynchosciara spermatocytes undergo highly characteristic morphological changes. In late meiosis the enlarged mitochondria fuse to form a single mitochondrial element which will ultimately extend the length of the spermatid tail. Our studies have shown that synthesis of a circular DNA occurs during this period of mitochondrial “differentiation.” This DNA has a density of 1.681 g/cm³; and its synthesis cannot be detected in somatic tissues such as salivary gland, fat body, or gastric cecum. From analysis of DNA extracted from mitochondrial pellets, we have shown that the circular DNA is associated with the mitochondria. The contour length of the mitochondrial DNA is 9 μm, equivalent to a molecular weight of 18 × 10⁶. Although most metazoan mitochondrial DNAs exhibit contour lengths of approximately 5 μm (10 × 10⁵ daltons), there is no extractable 5 μm circular DNA in these spermatocytes. Therefore, we conclude that either Rhynchosciara spermatocytes possess a distinct 9 μm mitochondrial DNA or that the spermatocyte mitochondrial DNA represents dimers of 5 μm monomers.     

Rate of follicle growth,change in follicle volume and stages of macromolecular synthesis during ovarian development in Musca domestica

At 21°C the first egg generation takes 6 days to develop. During this period the oöcyte volume increases by a factor of ×5000, and compared with an oögonium the growth factor amounts to ×100,000. The growth rate of the oöcyte increases with each stage of oögenesis, until at stage 5 it reaches 2.5 × 10⁶ μm³/hr. About 35% of the substance stored in the oöcyte originates from the nurse chamber. 30% of the volume is formed in the stage where the oöcyte synthesizes almost exclusively glycogen. Accordingly, about 30% of the volume is provided by the euplasmatic protein synthesis and by the yolk uptake.     

Infection of a nucleopolyhedrovirus to Neodiprion zhejiangenis Zhou & Xiao (Hymenoptera: Diprionidae)

Neodiprion zhejiangenis Zhou &; Xiao 1981 (Hymenoptera: Diprionidae) nuclear polyhedrosis virus (NezhNPV) is a biocontrol factor with high development potential and application prospects. To study the insecticidal activity of NezhNPV against the larvae of N. zhejiangenis, the susceptibility of larvae at different instars to different NezhNPV concentrations was determined based on laboratory bioactivity. At 2.0?×?10⁷ polyhedron inclusion body (PIB)/mL, the median lethal time required to kill 50% of the instar 2 and 3 larvae was approximately 5 d, whereas the median lethal time of the instar 4 and 5 larvae was 8–9 d. Interestingly, at the NezhNPV concentrations of 2.0?×?10³ and 2.0?×?10⁴ PIB/mL, the feeding ability of the surviving larvae was decreased by 57.4% and 76.4%, respectively, compared with the controls; the pupal weight at both concentrations was decreased by approximately 27%, and the adult emergence rate was decreased by 27.4% and 50.9%, respectively, with a significantly higher proportion of males than of females. The results showed that younger instar larvae of N. zhejiangenis were more susceptible to NezhNPV infection than older instar larvae. The larval mortality rate was dependent on the larval instar and NezhNPV concentration.     

Eimeria cicaki sp. n. and Isospora thavari sp. n. from the House Lizard Gehyra mutilata Boulenger in Malaysia*

SYNOPSIS. Oocysts and endogenous stages of new species of Eimeria and Isospora from the house lizard, Gehyra mutilata, are described. The ellipsoid to subspherical 2-layered oocysts of E. cicaki averaged 24.0 × 21.0 μm. Polar granules are present. Micropyle and oocyst residuum are absent. Ellipsoid sporocysts average 12.2 × 9.0 μm. A sporocyst residuum is present, but the Stieda body is absent. Endogenous stages are in epithelial cells of the small intestine. The subspherical single-layered oocysts of I. thavari average 23.8 × 22.8 μm. The polar granule is present; micropyle and oocyst residuum are absent. Ellipsoid sporocysts average 12.8 × 9.4 μm. Stieda body and sporocyst residuum are present. There are endogenous stages in epithelial cells of the small intestine.     

MORPHOLOGICAL CHANGES IN TOXIC AND NON-TOXIC MICROCYSTIS ISOLATES AT DIFFERENT IRRADIANCE LEVELS1

Light intensity (4.5–40.0 μEin m^?2 s^?1) and culture age had a pronounced effect on cell size and size range of a non-toxic axenic Microcystis isolate. The rate of cell volume increase (μm³ d^?1) was 1.03 × light intensity (μEin m^?2 s^?1) – 6.49. Average cell volume varied from 33 to 119 μm³, cells at higher light intensities being larger and having a larger size range. The effects on a toxic axenic Microcystis isolate were similar but less pronounced. Average cell volume ranged from 21–74 μm³. In general, cell size and especially size variability appear to be sensitive indicators of physiological state, with cells under stress conditions being larger and associated with a larger size range. The wide range of cell diameters observed at different irradiance levels (3.4–7.2 μm for the non-toxic and 1.8–6.4 μm for the toxic isolate), makes questionable the use of cell size as a taxonomic character without careful consideration of environmental conditions.