bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Density Dependence in Growth Patterns of Ceded Territory Walleye Populations of Northern Wisconsin: Effects of Changing Management Regimes
Authors: Sass Greg G. , Hewett Steven W. , Beard T. Douglas , Fayram Andrew H. , Kitchell James F.
Published: December 2004

We assessed density-related changes in growth of walleye Sander vitreus in the ceded territory of northern Wisconsin from 1977 to 1999. We used asymptotic length (L∞), growth rate near t0 (ω), and body condition as measures of walleye growth to determine the relationship between growth and density. Among lakes, there was weak evidence of density-dependent growth: Adult density explained only 0–6% of the variability in the growth metrics. Within lakes, growth was density dependent, L∞, ω, and body condition of walleyes changing with density for 69, 28, and 62% of the populations examined, respectively. Our results suggest that walleye growth was density dependent within individual lakes. However, growth was not coherently density dependent among lakes, which was possibly due to inherent differences in the productivity, surface area, forage base, landscape position, species composition, and management regime of lakes in the ceded territory. Densities of adult walleyes averaged 8.3 fish/ha and did not change significantly during 1990–1999. Mean L∞ and body condition of walleyes were significantly higher before 1990 than after 1990, which may indicate an increase in density due to changes in management regimes. The observed growth changes do not appear to be a consequence of the statewide 15-in minimum size limit adopted in 1990 but rather a response to the treaty rights management regime. We conclude that walleye growth has the potential to predict regional-scale adult walleye densities if lake-specific variables are included in a model to account for regional-scale differences among walleye populations and lakes.
Microsatellite Variation Indicates Population Genetic Structure of Bocaccio
Authors: Matala Andrew P. , Gray A. K. , Gharrett A. J. , Love M. S.
Published: December 2004

The California groundfish fishery has recently experienced a severe decline in both the biomass and harvest of bocaccio Sebastes paucispinis. The conservation and management actions necessary to reverse this trend require biological data, including information on the population structure, that reflect the basis of productivity. Using microsatellite loci, we conducted a population genetic analysis of bocaccio with samples from waters ranging from British Columbia to Baja California. A log-likelihood test of homogeneity of allele frequencies over the entire data set was significant, although partitioning variation by FST analysis revealed no statistically significant geographic divergence among populations, and no evidence of a geographic cline of structure was detected in a Mantel test. By partitioning the heterogeneity among populations into homogeneous groups of adjacent populations, we observed structure related to geographic location that could be consistent with the divisions of current regimes among the California Current system, a neighborhood model of isolation and limited gene flow, or both. Resolving more detailed structure was not possible with the numbers of samples and collections available, but our observations indicate that caution should be exercised in making conservation or management decisions that do not consider genetic structure or that assume its absence.
Comparison of Fish Density Estimates from Repeated Hydroacoustic Surveys on Two Wyoming Waters
Authors: Gangl R. Scott , Whaley Roy A.
Published: December 2004

The ability to actively sample fish populations is a major advantage of hydroacoustic assessment. This technique does not affect fish behavior, and it typically produces more precise abundance estimates than do other gears. Thus, hydroacoustic surveys repeated on a closed population should produce similar fish density estimates. We sought to demonstrate this on inland waters using multiplexed side- and down-looking transducers and target-tracking enumeration methods. To test the repeatability of hydroacoustically derived fish density estimates, we conducted complete hydroacoustic surveys daily over three consecutive days on two Wyoming reservoirs, with a parallel transect design at one reservoir and a zigzag design at the other; this mimicked two designs commonly used during routine hydroacoustic surveys. These repeated surveys were performed on each reservoir monthly from April to September 2001. We used a Kruskal–Wallis test to detect significant differences in fish density estimates among repeated surveys for each lake during each month. There were no significant differences among daily surveys when sampling conditions were constant. During periods of increased wind we increased the aiming-angle of the side-looking transducer to minimize wind noise interference at the lake surface. This produced significantly lower density estimates than on calm days. We concluded that sampling under marginal conditions affected the results of the survey and inhibited the comparability of samples over time.
Postrelease Rate of Loss of Juvenile Red Drum Stocked out of Season in the Chassahowitzka National Wildlife Refuge, Florida
Authors: Sherwood Edward T. , Murie Debra J. , Parkyn Daryl C.
Published: December 2004

Rates of loss of juvenile red drum Sciaenops ocellatus (∼85 mm total length) stocked out of season were estimated using hatchery releases and ultrasonically tagged fish in Pumpkin and May creeks in the Chassahowitzka National Wildlife Refuge on the Gulf coast of Florida. In Pumpkin Creek, approximately 7,000 of the 10,000 fish released on 27 June 2000 survived combined transport mortality (2%) and 24-h acute mortality (28 ± 8.7% [mean ± SE] n = 6). In May Creek, approximately 5,100 of the 10,000 fish released on 29 June 2000 survived combined transport (7.5–10%) and 24-h acute (44 ± 0%, n = 2) mortality. Catch curve estimates of the instantaneous “rate of loss” (mortality or emigration) within 5 d were 0.46/d and 0.50/d for Pumpkin and May creeks, respectively. Red drum with ultrasonic transmitters (n = 12) also rapidly “disappeared” from the creeks within 4 d after release. These are the first estimates of postrelease rate of loss for juvenile red drum released out of season on the west coast of Florida. Understanding the causes of this overall rapid rate of loss will be critical to evaluating the success of out-of-season releases of red drum in Florida.
Abundance and Demography of Channel Catfish in a Large Northern River
Authors: Haxton Tim , Punt Kirby
Published: December 2004

A northern population of channel catfish Ictalurus punctatus was assessed to ascertain the abundance and demographics of the population. Standardized trap-netting was conducted from 1997 to 2002 in six reaches of the Ottawa River. A total of 13,197 channel catfish were sampled. The relative stock density was 18.5% stock, 47.7% quality, 27.2% preferred, 4.4% memorable, and 0.5% trophy. Mean relative weight was 71 for all channel catfish combined and for the different size-classes it was 37 for stock, 61 for quality, 88 for preferred, 133 for memorable, and 120 for trophy. Growth was slow compared with that of more southerly populations but longevity was greater (ages of up to 26 years). Annual mortality was 15.7%. Population estimates ranged from 38,445 to 220,924 in the various reaches, and density ranged from 3.5 to 31.7/ha. Channel catfish are an abundant and underutilized species in the Ottawa River; however, given their life history traits, this fishery is susceptible to overexploitation.
Stock-Specific Migration Timing of Adult Spring–Summer Chinook Salmon in the Columbia River Basin
Authors: Keefer Matthew L. , Peery Christopher A. , Jepson Michael A. , Tolotti Kenneth R. , Bjornn Theodore C. , Stuehrenberg Lowell C.
Published: December 2004

An understanding of the migration timing patterns of Pacific salmon Oncorhynchus spp. and steelhead O. mykiss is important for managing complex mixed-stock fisheries and preserving genetic and life history diversity. We examined adult return timing for 3,317 radio-tagged fish from 38 stocks of Columbia River basin spring–summer Chinook salmon O. tshawytscha over 5 years. Stock composition varied widely within and between years depending on the strength of influential populations. Most individual stocks migrated at similar times each year relative to overall runs, supporting the hypotheses that run timing is predictable, is at least partially due to genetic adaptation, and can be used to differentiate between some conspecific populations. Arrival timing of both aggregated radio-tagged stocks and annual runs was strongly correlated with river discharge; stocks arrived earlier at Bonneville Dam and at upstream dams in years with low discharge. Migration timing analyses identified many between-stock and between-year differences in anadromous salmonid return behavior and should aid managers interested in protection and recovery of evolutionarily significant populations.
Angling Pressure and Trout Catchability: Behavioral Observations of Brown Trout in Two New Zealand Backcountry Rivers
Authors: Young Roger G. , Hayes John W.
Published: December 2004

Angling pressure is increasing in many recreational trout fisheries throughout the world. There is a strong perception among anglers that trout become harder to catch after being disturbed by other anglers, thus affecting the quality of their angling experience. However, there is little scientific evidence to support or refute this perception. We measured the response to angling pressure in two rivers in New Zealand: The remote Ugly River and the more heavily fished Owen River. Both of these rivers have fisheries for brown trout Salmo trutta. The numbers of trout seen and caught over the length of four 3-d angling trips were compared between rivers. The behavioral responses to angling of naïve trout in the Ugly River were compared with those of Owen River trout and trout that had been angled previously from the Ugly River. The proportion of the trout population in the study reaches caught by two anglers after four 3-d trips was estimated as between 11% and 23% in the Owen River and up to 47% in the Ugly River. The most marked behavioral response to angling pressure was in the Ugly River, where trout that had been caught and released or merely disturbed by anglers were rarely seen over the following days. No such hiding response was observed in the Owen River. A learning response was also evident, as trout that had been fished previously were more likely to be scared by anglers or required smaller, low-profile flies before being caught than naïve trout. Faced with increasing angling pressure, anglers can perhaps cope with the observed learning response by improving their techniques to outsmart trout. However, the hiding response observed in the remote river indicates that controls on angling, such as access restrictions, may be required to maintain quality angling experiences in these wilderness fisheries.
Using Time-Lapsed Video to Estimate Survey Life for Area-under-the-Curve Methods of Escapement Estimation
Authors: Shardlow Tom
Published: December 2004

Accurate estimation of spawner populations for Pacific salmon Oncorhynchus spp. is critically important in stock assessment for fisheries management and science. Survey life (SL) is one essential component for area-under-the-curve (AUC) estimation of spawner populations. However, AUC spawner estimates often rely on a constant or borrowed estimate of SL because reliable estimates require extensive and costly annual field programs. Using a constant SL estimate can introduce serious bias when estimating spawner populations for sockeye salmon O. nerka as well as other salmon species. In this study, inexpensive video observations of redd residency time (RRT) of female sockeye salmon were used to approximate SL. Data from past studies indicate that RRT and SL are often close in duration for sockeye salmon, Chinook salmon O. tshawytscha, and coho salmon O. kisutch. In addition, SL estimates for male and female sockeye salmon are not significantly different. As a result, the RRT of female sockeye salmon, as observed by time-lapsed video recordings, can be used to provide an inexpensive annual estimate of sockeye salmon SL.
Simulated Impacts of Tournament-Associated Mortality on Largemouth Bass Fisheries
Authors: Allen M. S. , Rogers M. W. , Myers R. A. , Bivin W. M.
Published: December 2004

We used creel survey data combined with a simulation model to assess how tournament-associated mortality could increase exploitation of largemouth bass Micropterus salmoides and influence largemouth bass fisheries. We obtained estimates of total largemouth bass harvest (HARV) and total tournament catch (TC, i.e., the number of fish brought to judging stations) at nine lakes from Arkansas, Florida, and Texas. The ratio of TC to HARV exceeded 1.0 at five of the nine lakes studied and ranged from 0.35 to 5.18. We simulated potential tournament-associated mortality rates ranging from 0% to 70% applied to TC fish. Because exploitation was not known, we modeled harvest estimates to represent four potential exploitation rates (5, 15, 25, and 35%). The age-structured simulation model predicted that at three of nine lakes where TC/HARV ratios exceeded 3.0, tournament-associated mortality rates of 20–30% could cause 5–12% declines in the abundance of largemouth bass larger than 300 mm total length and resulted in declines in population size structure. At lakes with TC/HARV ratios of less than 1.0 (N = 4 lakes), the model predicted that tournament-associated mortality would have a negligible impact (i.e., <5%) on the abundance of adult fish and population size structure, regardless of the tournament-associated mortality rate. Tournament-associated mortality may not significantly influence most largemouth bass fisheries. However, in lakes where tournament catch was substantially higher than harvest, tournament-associated mortality could encompass a large portion of fishing-associated mortality and would influence largemouth bass fisheries if harvest estimates corresponded to exploitation rates of 15% or more. Exploitation measures based solely on harvest may not reveal significant portions of fishing-associated mortality for fisheries where tournament catch can exceed harvest.
Anchor and Visible Implant Elastomer Tag Retention by Hatchery Rainbow Trout Stocked into an Ozark Stream
Authors: Walsh Maureen G. , Winkelman Dana L.
Published: December 2004

As part of a study to evaluate the stocking of rainbow trout Oncorhynchus mykiss in an Oklahoma Ozark stream, we tagged 2,542 hatchery-reared rainbow trout (123–366 mm total length) with individually numbered Floy FD-68B anchor tags and visible implant fluorescent elastomer (VIE) tags. We experimentally stocked double-marked rainbow trout into a small northeastern Oklahoma stream from November 2001 to March 2002 and resampled them monthly from December 2001 to October 2002 by electrofishing. Anchor tag retention was 91% through 6 months, and VIE tag retention was 96% through 6 months despite extensive handling of fish within 24 h of tagging. Based on the ease of application, high visibility, and high retention observed in this study, we recommend the use of VIE tags as a batch mark in similarly sized, similarly pigmented fish. The retention of VIE tags was slightly higher than that of anchor tags, and cost per fish was less for VIE than for anchor tags. However, VIE tags would have limited utility if numerous individual tags are necessary; therefore, we recommend anchor tags as individual marks in similarly sized salmonids. Retention for both tag types was relatively high and could be corrected for when estimating population parameters from tagging data.
Catalysis of hydrosilylation part XVIII. Pt(PPh3)2(CH2CH2) – a versatile catalyst for hydrosilylation of olefins
Authors: Marciniec B , Guliński J , Urbaniak W , Nowicka T , Mirecki J
Published: December 2004

Pt(PPh3)2(CH2CH2) appeared to be a versatile catalyst in hydrosilylation of alkenes (with 5–22 C atoms) as well as of functionalized alkenes such as allyl chloride, allylamine, allyl methacrylate and vinylsilanes. In comparison with a well‐known Speier catalyst or with Pt(PPh3)4, this complex is characterized by a very high effectiveness (activity and selectivity) and relative resistance to oxygenation and it may be applied in recycling runs with a minor induction period. The catalytic processes examined are of great industrial importance since they lead to a synthesis of alkylsilanes, disilylethanes and silane coupling agents.
Synthesis and characterization of rac‐1,2‐bis(palmitoyloxy)‐3‐propyl (2‐trimethylarsonioethyl)phosphonate, an arsenic‐containing phosphonolipid
Authors: Junk Thomas , Pappalardo Giuseppe C , Irgolic Kurt J
Published: December 2004

Arsenic analogs of lecithins (i.e. with replacement of nitrogen by arsenic in the choline group) are probably trace constituents of phospholipids in many organisms. Attempts to synthesize 1,2‐bis(palmitoyloxy)‐3‐propyl 2‐trimethylarsonioethyl phosphate (arsenolecithin) according to wellestablished procedures for the synthesis of the corresponding nitrogen compound failed. However, 1,2‐bis(palmitoyloxy)‐3‐propyl 2‐trimethylarsonioethylphosphonate, an arsenic‐containing phosphonolipid, was obtained in 16% yield by reacting 1,2‐bis(palmitoyloxy)‐3‐iodopropane with silver 2‐trimethylarsonioethylphosphonate in isopropanol. The precursors to the arsenic‐containing phosphonolipid were obtained by quaternization of trimethylarsine with diethyl 2‐bromoethylphosphonate, hydrolysis of the resulting product with concentrated hydrochloric acid, and reaction of the phosphonic acid with silver oxide to give silver 2‐trimethylarsonioethylphosphonate. Quaternization and hydrolysis proceeded almost quantitatively. The silver phosphonate was not isolated but was used in situ.
Laser photodissociation of organometallic compounds on a cryosubstrate
Authors: Kawasaki Masahiro , Nishi Nobuyuki
Published: December 2004

The photodissociation dynamics of organometallic compounds (tetramethyltin, trimethylgallium, trimethylindium and dimethylzinc) adsorbed on a quartz substrate at 100 K have been studied by time‐of‐flight mass spectrometry, detecting mainly CH3 photofragments. Shapes of the time‐of‐flight spectra depend on the flux of the dissociation laser at 193 nm and the thickness of multilayers of organometallic compounds. In thick layers, not only a low energy component but also a high energy component are observed in the time‐of‐flight spectrum of the CH3 photofragments. In thin layers, relaxation processes take place so quickly that the product time‐of‐flight profiles are characterized by a Maxwell–Boltzmann temperature profile.
New chelated complexes of bis‐β‐carboalkoxyethyltin(IV) dichloride with S‐benzyldithiocarbazate Schiff bases
Authors: Gopinathan Sarada , Degaonkar M P , Gopinathan C
Published: December 2004

The Schiff bases [H2SBSaD], [H2SBVD] and [H2SBND], derived by the condensation of S‐benzyldithiocarbazate and salicylaldehyde, 2‐hydroxy‐3‐methoxybenzaldehyde and 2‐hydroxy‐1‐naphthaldehyde respectively, react with diestertin dichlorides, R2SnCl2 [R=CH2CH2CO2CH3, CH2CH2CO2C2H5 or CH2CH2CO2C4H9] in 1:1 molar proportion to yield chlorine‐substituted complexes of the type R2Sn(Schiff base), the base being tridentate. The complexes are characterized on the basis of their elemental analyses, IR and 1H NMR spectral studies. The 13C and 119Sn NMR and the tin‐carbon coupling constant data reveal the structures of the complexes to be octahedral with trans ester grouping, and bidentate ester linkages. The pentacoordinated complex (CH3)2Sn(SBSaD) was prepared by the reaction of dimethyltin oxide with H2SBSaD in equimolar proportions.
Mono‐organotin(IV) compounds as esterification and transesterification catalysts
Authors: Hobbs L A , Smith P J
Published: December 2004

A series of monoorganotin(IV) compounds has been investigated as transesterification catalysts for the reaction of butyl propionate with methanol. The most active catalysts were found to be those which contain tin‐halogen bonds, e.g. monobutyltin trichloride (BuSnCl3), and the least effective were the coordinatively saturated monoorganotin derivatives. Certain of the mono(2‐carboalkoxyethyl)tin compounds were found to undergo a facile autocatalysed transesterification reaction with alcohols. Coordination of the carbonyl group in the ester to the tin catalyst is an important factor influencing its activity. A study of the catalysis of the esterification of propionic acid by BuSnCl3 is reported.
Photodissociation of multilayered trimethylaluminum adsorbed on a cryogenic substrate: A time‐of‐flight mass‐spectrometric study
Authors: Kobayashi Makoto , Sato Akihiko , Tanaka Yugo , Shinohara Hisanori , Sato Hiroyasu
Published: December 2004

Photodissociation of trimethylaluminum [Al(CH3)3] adsorbed on a silica (SiO2) substrate at 110 K has been studied by multiphoton ionization time‐of‐flight mass spectrometry. Translational energy distributions of aluminum and AlCH3 fragments can be fitted with a composition of two Maxwell–Boltzmann distributions. The two components are attributed to different environments of photodissociating parent molecules in the multilayer.
High‐Tech‐Folien. Neue Anwendungen für Fluoreszenzfarbstoffe
Authors: Haremza Sylke
Published: December 2004

Wir alle kommen täglich – bewußt oder unbewußt – mit Gegenständen in Kontakt, bei denen fluoreszierende Verbindungen eingesetzt werden. Dem Bedürfnis nach einem „reinen”︁, strahlenden Weiß wird seit Jahrzehnten durch den Einsatz von optischen Aufhellern, vor allem in Textilien und Papier, Rechnung getragen. Zum gewohnten Alltagsbild zählen Sonderlackierungen von Feuerwehr‐ und Rettungsfahrzeugen ebenso wie Reklamedrucke oder „knallbuntes”︁ Sport‐ und Freizeitequipment vom Surfbrett bis zur Schiedsrichterkarte.
Vielfalt an Ausbildungswegen. Materialwissenschaften – Studium und Arbeitsmarkt
Authors: Thieme Peter
Published: December 2004

Der lange Marsch in Richtung Materialwissenschaften begann, als der Mensch lernte, aus Erzen Metalle zu schmelzen und diese durch gezielte Variation seinen Bedürfnissen anzupassen. Ursprünglich ein auf Erfahrung beruhendes Handwerk der Metallgießerei, der Keramikherstellung und der Glasschmelze, sind die Materialwissenschaften inzwischen dank der grundlegenden Erkenntnisse der modernen Chemie und Physik zu einer eigenständigen Forschungsrichtung geworden. Wie sollten die Universitäten auf diese Entwicklung reagieren und welche Perspektiven haben Absolventen mit einer Ausbildung in dieser Fachrichtung auf dem Arbeitsmarkt?
Wissenschaft aktuell
Authors: Janenika Lother
Published: December 2004

Die Verwunderung, daß ein gasförmiges, niedermolekulares „Umweltgift”︁ als Signalvermittler im tierischen Organismus dient, ist bei Medizinern und Biochemikern noch frisch, obgleich es die hundert Jahre alte Erfahrung mit Kranzgefäß‐erweiternden Nitrodrogen endlich auf eine solide Basis stellt.
The fine structure of neurons and synapses in the entopeduncular nucleus of the cat
Authors: Adinolfi Anthony M.
Published: December 2004

Cat brains were fixed by vascular perfusion with glutaraldehyde and paraformaldehyde and the entopeduncular nucleus was examined by electron microscopy. The fine structure of most neurons in this region does not significantly differ from earlier descriptions of large neurons. Distinctive features of perikarya and dendrites include juxtanuclear Nissl bodies, unique lamellar configurations composed of agranular cisternae separated by thin layers of dense granular matrix and continuous with the granular endoplasmic reticulum, localized swellings of dendrites, and dendritic branchlets or gemmules which invaginate a single nerve terminal. Cell surfaces are ensheathed by interdigitating nerve terminals and glial lamellae. Two types of endings are distinguished on the basis of their diameter and the size of their synaptic vesicles. Further division depends on distribution of the vesicles within a terminal, where the synapses occur, and the presence of postsynaptic bodies. Most terminals are about one micron and contain closely packed synaptic vesicles measuring 515 Å (S. D. 72.7 Å). Larger terminals containing fewer smaller (312 Å) synaptic vesicles and neurofilaments or neurotubules near the periphery have been interpreted as boutons‐en‐passage. It is suggested that different afferent projections end in a similar manner on restricted portions of the neuronal surfaces in the entopeduncular nucleus.
The cortico‐thalamic projections from the sensorimotor cortex of Galago crassicaudatus
Authors: Campos‐Ortega J. A. , Clüver P. F. de V.
Published: December 2004

The cortico‐thalamic pathways from the sensorimotor cortex of the prosimian Galago crassicaudatus were studied after cortical lesions. The Glees method and several modifications of the Nauta technique were used. A short description of the thalamic nuclei in Galago is given. The motor cortex was found to project to the following nuclei: reticularis thalami, lateralis anterior, lateralis ventralis oralis, lateralis dorsalis intermedius, the pars paralamellaris of the nucleus lateralis ventralis posterior, the intralaminar nuclei, parafascicularis‐centrum medianum complex, lateral third of the mediodorsalis, praetectalis, zona incerta, H fields of Forel and the subthalamic nucleus. The cortical projections to nucleus centrum medianum was found to be topically organized.

The sensory cortex was found to project to the following nuclei: reticularis thalami, lateralis dorsalis intermedius, paracentralis, parafascicularis, pars lateralis and pars medialis of the nucleus lateralis ventralis posterior, praetectalis, posterior, zona incerta, and the H fields of Forel. The topical organization of the cortical projection to the lateral complex and posterior nucleus is discussed.
An autoradiographic study of the development of the anterior thalamic group and limbic cortex in the rabbit
Authors: Fernández Victor
Published: December 2004

Using autoradiographic technique the migratory movements of cells destined to form the anterior thalamic nuclear group and the limbic cortex were studied in 54 embryos or newborn rabbits the mothers of which were injected with a single dose of tritiated thymidine on the fifteenth to twenty‐fifth day of gestation.

Neurons which form the anterior thalamic group originate between the fifteenth and eighteenth day of gestation. An orderly relation exists between the time of origin of the anterior thalamic neurons and their definitive position within the dorsal thalamus. The cells which originate earliest lie most laterally in the dorsal thalamus; those which originate later lie successively more medially. No nucleus in the anterior group is isochronic in regard to the origin of its cells and in each a latero‐medial gradient corresponding to early‐late origin is apparently present.

Neurons forming the limbic cortex (upon which the anterior thalamic group projects) originate between the fifteenth and twenty‐fifth day of gestation. The anterior and the posterior limbic regions seem to develop synchronously. In agreement with other workers it is concluded that neurons which originate earliest form the VIth layer of the differentiated cortex while those which originate later form successively the more superficial cortical layers. No retrograde movements of the migrating cells were observed. It is suggested that during cortical development each migratory wave of cells, after passing the thickness of the already existing cortical plate, constitutes at some stage the most superficial cell layer of the then existing cortex.
Development of neuronal connections with skin grafts in frogs: Behavioral and electrophysiological studies
Authors: Jacobson Marcus , Baker Robert E.
Published: December 2004

Three types of skin grafts were made in frog tadpoles at various stages of development. Skin on the trunk was excised and replaced in a back‐to‐belly inverted position; or skin on the back was grafted in a head‐to‐tail inverted position; or small patches of back and belly skin were exchanged. During metamorphosis these animals devloped normal reflexes in response to stimulating the skin graft. Some days later, reflexes misdirected to the original position of the grafted skin occurred on stimulating back‐to‐belly inverted grafts made before larval stage XV. The area of skin giving rise to misdirected reflexes enlarged gradually to occupy most of the graft. Only normal reflexes were elicited from back‐to‐belly inverted grafts made after stage XV and from the other types of grafts made after stage I. Misdirected reflexes were permanent. However, re‐rotation of back‐to‐belly inverted grafts in adult frogs resulted in recovery of normal reflexes in some cases.

The receptive fields of cutaneous nerves were mapped electrophysiologically and were similar in tadpoles and frogs with skin grafts and normal controls. No changes in receptive fields were detected during development of during the period when normal or misdirected reflexes appeared. We concluded that misdirected reflexes were not caused by changes in the peripheral receptive fields but were due to changes in the central nervous system which occurred after the sensory nerves had connected with the skin graft.
Ansa and fasciculus lenticularis of carnivora
Authors: Grofová I.
Published: December 2004

The fiber systems of the globus pallidus and the nucleus entopenduncularis were studied in normal brains of the cat and of the brown bear, stained by the Häggqvist method.

The globus pallidus in both animals is traversed by bundles of the internal capsule. No division into external and internal segments can be made. Pallidal fibers do not form fascicles resembling the ansa or fasciculus lenticularis of primates. They are thicker in the bear (3.5–5 μ) than in the cat (2–3.5 μ).

The entopeduncular nucleus in the bear is prominent and lies close to the globus pallidus. Fibers arising in its grey network are rather thick (5–6.5 μ) and at its rostral level assemble to form the ansa lenticularis. Subsequently they traverse the internal capsule in slender ribbons to assemble again in the fasciculus lenticularis. Corresponding fibers in the cat are thinner (3–4.5 μ) and do not form distinct fascicles. Their course resembles that in the bear but they reach Forel's field rostral to the subthalamic nucleus. The fasciculus thalamicus and fasciculus pallidohypothalamicus are composed of these fibers.

Edinger's comb system is well developed in both animals. Its dorsal part consists of pallidal fibers, representing the fasciculus pallido‐subthalamicus. The findings furnish further evidence that the nucleus entopeduncularis actually represents the internal pallidal segment of the primates.
Changes in nerve cell bodies during the myelination of their axons
Authors: Julio Martinez A. , Friede Reinhard L.
Published: December 2004

Changes in nerve cell perikarya were studied at twelve phases of the myelination period of rat sciatic nerve; data are given on nuclear and nucleolar diameters, the area of cytoplasm, neuronal packing density, length of the nerve, limb and femur, and on the distribution of chromophil substance in the cytoplasm. The study was coordinated with and supplements a previous quantitative electron microscopic study of myelination in rat sciatic nerve.

The amounts of cytoplasm in anterior horn motor cells and in large cells of the spinal ganglia increased during myelination, and growth curves for these two cell populations were nearly identical. The increase in cytoplasm was compared with the increase in axoplasm, calculated from the increase in caliber and in fiber length. The volumes of axoplasm and of cytoplasm in the perikarya increased in strict proportion, indicating a coordinated growth of axons and perikarya during the myelination period. Axon growth in turn, occurs in strict coordination with myelin deposition.

The growth curve for the small cells in spinal ganglia differed entirely and is consistent with the assumption that nonmyelinated or very thinly myelinated fibers arise from these cells. Changes in the volume of cytoplasm in nerve cells were associated with changes in the nucleo‐cytoplasmic relation, a decrease in neuronal packing density, and a redistribution of RNA in the cells.
The fine structure of the circumesophageal nerve in several decapod crustaceans
Authors: Skobe Ziedonis , Nunnemacher Rudolph F.
Published: December 2004

In order to obtain a better understanding of the significance of the anatomy of the crustacean nervous system with respect to behavior entire cross sections of circumesophageal connective nerves were examined by electron microscopy to determine the number and diameter of nerve fibers in the following species: Crangon septemspinosa, Pagurus pollicaris, P. longicarpus, Carcinus maenas, Cal. linectes sapidus, Podophthalmus vigil, Cancer irroratus, C. borealis, Grapsus grapsus, Gecarcinus lateralis, Uca pugnax, and Libinia emarginata. The diameter of the fibers ranged from 0.1 μ to 80 μ; in each case the larger fibers being in the dorsal portion of the connective. In most species the smaller fibers were most numerous; with increasing diameter the fibers became less numerous. The total number of fibers ranged from 1,500 to 9,600. This interspecies difference is primarily due to variance in the number of very fine fibers. Unusual patterns of fiber distribution appeared in Crangon and Callinectes, which had no fibers of very small diameter, in Pagurus with a large bundle of such fine fibers, and in Grapsus, which had several giant fibers. In some of the species the peculiar fiber distributions appear to be related to particular adaptations.
Efferent connections of the periaqueductal gray matter in the cat
Authors: Hamilton Betty L. , Skultety F. Miles
Published: December 2004

Electrolytic lesions were stereotaxically placed in the dorsal and ventral areas of the mesencephalic periaqueductal gray in the cat. A dorsal angular approach was made so that mechanical electrode damage was contralateral to the lesion, or a posterior approach through the fourth ventricle was employed to avoid electrode damage. The brains were sectioned coronally and sagittally and stained with a modifield Nauta‐Gygax or Fink‐Heimer stain.

Degeneration from the dorsal lesions was chiefly in a radial pattern to the superior colliculus, inferior colliculus and mesencephalic reticular area. Also, fibers angled out of the dorsal gray, crossed the midline and joined the commissure of the superior colliculus, some taking a ventrolateral course through the colliculi and others running ventrally along the borders of the gray. Degeneration was traced caudally to the cuneiform nucleus and adjacent reticular area. Rostrally, fibers traveled in the dorsal longitudinal fasciculus to the pretectal area, lateral habenular nucleus and finally, the posterior hypothalamic area.

Ventral lesions showed the same radial pattern of degeneration and fibers in the superior colliculus commissure. Caudally, fibers could be traced to the cuneiform nucleus, reticular area and inferior olive. The rostral course of fibers in the dorsal longitudinal fasciculus was similar, though there were additional connections with the ventral tegmental area of Tsai, the fields of Forel, and the parafascicular nucleus of the thalamus.
The corticospinal tract of the marsupial phalanger (Trichosurus vulpecula)
Authors: Martin George F. , Megirian David , Roebuck A.
Published: December 2004

The origin, course and distribution of corticospinal fibers were determined in the marsupial phalanger (Trichosurus vulpecula) by the use of the Nauta‐Gygax technique. Findings in 15 cases of cortical lesions indicated that corticospinal fibers arose mainly within the immediate postorbital and midcortical (parietal) regions and descended throughout the ipsilateral pyramidal bundle. The great majority of the fibers cross in the caudal medullary pyramidal decussation. At spinal cord levels, such fibers compose a large dorsal corticospinal tract located ventrally within the dorsal funiculus and a smaller lateral bundle descending in the medial part of the lateral funiculus. Even in cases of complete unilateral decortication, degenerating corticospinal fibers could be traced only as far caudally as T–10.

At cervical levels, the majority of cortiospinal fascicles arborize within the medial portions of Rexed's laminae III through VI. A smaller contingent of fibers extends into the lateral portions of these same laminae. Of particular note were corticospinal fibers which appeared to end within lamina VII and, to some extent, within lamina VIII. Many of the fibers ramifying within lamina VII did so in close proximity to the motor neurons of lamina IX; none, however, could be identified within the confines of lamina IX. At thoracic levels, where lamina VI is indistinct, terminal degeneration of rapidly decreasing amount appeared within the medial portions of laminae IV, V and VII. At more caudal thoracic levels, the area of apparent corticospinal fiber termination was limited mainly to the medial and, to a much less extent, the lateral portions of lamina V.
A study of the median giant fiber system in the cephalic ganglion of a crayfish (Procambarus clarkii)
Authors: Horiuchi Etsuko , Hayashi Hideo , Takahashi Isao
Published: December 2004

The pathway of the median giant fiber in the crayfish cephalic ganglion (brain) was reconstructed from serial sections. The median giant fiber in the para‐esophageal nerve runs anteriorly and enters the brain. After turning medially, it given of a branch which further divides into two branches. These branches run ventrally and outwards and finally enter the ipsilateral antennule nerve and ventrally. It decussates and makes contact with the contralateral median giant fiber near the midline. After decussating, the fiber again divides into two branches. One runs outwards and ventrally and finally enters the contralateral antennule nerve. The other runs anteriorly at first and then turns ventrally immediately behind the rostral cellular group. Near the ventral surface of the brain the fiber turns posteriorly and connects with a large soma 100–150 μ in diameter. In its course to the soma, the main fiber decreases in width to one‐eighth of the diameter of the axon in the para‐esophageal nerve.
The corticopontine projection in the cat. I. The projection from the proreate gyrus
Authors: Brodal Per
Published: December 2004

Following large and small lesions (in many cases bilateral) of the proreate gyrus in adult cats the ensuing degeneration in the pontine nuclei was studied with the silver impregnation methods of Nauta and of Fink and Heimer. Lesions were produced by transdural thermocoagulation

The main results are as follows:

All parts of the proreate gyrus on the convexity of the hemisphere emit fibers to the pontine nuclei. The projection from the dorsal part is somewhat less intense than that from the ventral part. The density of projection from the proreate gyrus is far less than from the anterior sigmoid gyrus (motor cortex).

The proreate gyrus projects upon two longitudinal columns in the ipsilateral pontine gray. One column is located medially, the other laterally.

The exact localization of these columns has been compared with the localization of the columns projected upon by the anterior sigmoid gyrus. No clear difference has been found.

No topical localization could be demonstrated within the pontine projection from the proreate gyrus, which in this respect differs from the projection from the anterior sigmoid gyrus (motor cortex), which projects somatotopically upon both columns. Possible relations between the proreate gyrus and the cerebellum are discussed.
The corticopontine projection in the cat. II. The projection from the orbital gyrus
Authors: Brodal Per
Published: December 2004

Following large and small lesions of the orbital gyrus in adult cats the ensuing degeneration in the pontine nuclei was studied with the silver impregnation methods of Nauta and of Fink and Heimer. Lesions were produced by transdural thermocoagulation. The main results are as follows:

All parts of the orbital gyrus give off fibers to the pontine nuclei. The density of projection is less than from the anterior ectosylvian gyrus (second somatosensory area).

The orbital gyrus projects upon four longitudinal columns within the pontine nuclei. One is located medially, one ventromedially, one ventrolaterally and one dorsolaterally.

The exact localization of these columns has been compared with the localization of the columns projected upon by the anterior ectosylvian gyrus. Three of the columns (the medial, ventrolateral and dorsolateral) appear to be projected upon by both gyri, while the fourth one receives afferents from the orbital gyrus only.

A topical localization exists within the projection from the orbital gyrus insofar as the anterior part of the gyrus projects onto the medial, ventrolateral and dorsolateral columns, while the posterior part projects onto the ventromedial column mainly.

Whether a somatotopical localization is present within the projection to some or all of the columns can not be decided from the material.
Classification of neurons in the ectosylvian auditory cortex of the dog
Authors: Tunturi Archie R.
Published: December 2004

The rapid Golgi method was used to classify the neurons in the MES and PES auditory areas of the dog. Small pyramids were found in layer II with percentages of 12% in the MES area and 8.1% in the PES area. Medium sized pyramids possessed a bimodal distribution, the first in layer IV and the second in V, with 58% in MES and 62% in PES. Large pyramids were found in layer V with a proportion of 12.5% in MES and 17% in PES. The star neurons were found in layer III with proportions of 5.9% in MES and 4.0% in PES. The double bouquet neurons in layer III had a proportion of 1.5% in MES and 1.7% in PES. Fusiform neurons in layers V and VI were in proportions of 2.2% in MES and 6.4% in PES. The principal finding was a special auditory cell occurring in layers V and VI of the MES area with a proportion of 8% and from 14.8 to 34.8% in the strata between 1 and 2 mm. Less than 1% of neurons in the PES area were identified as special cells. Its appearance was an inverted pyramidal cell with a large dendrite extending toward the white matter from which the axon arose.
Perikaryal synthetic function following reversible and irreversible peripheral axon injuries as shown by radioautography
Authors: Engh Charles A. , Schofield Brian H. , Doty Stephen B. , Robinson Robert A.
Published: December 2004

Regenerative activity within perikarya of peripheral neurons was studied using light microscopic and standard autoradiographic techniques. Relative incorporation of H3‐leucine into injured neurons was used as an index of their regenerative activity. Reversible and irreversible sciatic nerve injuries were used as the experimental model. Results were correlated with microscopic and functional assessment of progress in nerve regeneration in each animal.

Both reversible and irreversible axonal injuries resulted in chromatolysis and initially decreased 30 minute incorporation of the labeled axonal protein precursor into injured cells. A late increase in 30 minute incorporation of the labeled amino acid occurred only in animals subjected to reversible axon injury. In sometimes greater than normal cytoplasmic basophilia and always accompanied demonstrable return of nerve function.

These findings are correlated with present concepts of perikaryal synthetic requirements during the various phases of peripheral axon regeneration. It is suggested that the increased synthetic activity within the perikaryon necessary for axon maturation results from the return of a trophic perikaryal stimulus from reinnervated peripheral structures.
A study of normal and congenitally abnormal retinogeniculate projections in cats
Authors: Guillery R. W. , Kaas J. H.
Published: December 2004

Retinogeniculate terminations have been studied by fiber degeneration and microelectrode mapping methods in normal cats and in Siamese cats in which the retinogeniculate pathway is congenitally abnormal. The normal representation of the visual field, including the monocular temporal crescent, has been determined. It has also been shown that there is a cellular discontinuity in lamina A which corresponds to the blind spot or optic disc. In normal cats four geniculate layers receive retinogeniculate terminals; two layers (A and C) receive contralateral and two layers (A1 and C1) receive ipsilateral afferents.

In Siamese cats laminae A and C are normal. Lamina A1 is broken up into four main cell segments. Two of these receive a normal input from the ipsilateral temporal hemiretina; two receive an abnormal projection from the contralateral temporal hemiretina. The abnormal projection originates primarily from a vertical strip of retina about 20°–25° in width that lies just temporal to the area centralis. Within this abnormal projection a normal retinotopic sequence is maintained but, since this projection goes to the contralateral instead of the ipsilateral lamina A1, the abnormal segments of lamina A1 receive a mirror‐image of the normal representation.

Lamina C1 and the medial interlaminar nucleus receive an abnormal contralateral input from the temporal hemiretina similar to that found in lamina A1.