A new species of Dipetalonema (Filarioidea: Onchocercidae) from Ateles chamek from the Beni of Bolivia

We describe a new species of Dipetalonema occurring in the body cavity of Ateles chamek (Humboldt, 1812) from north-central Bolivia. Morphologic characters serving to separate Dipetalonema yatesi n. sp. from known forms include a vagina vera with a simple tube and thin walls and a left spicule, which possesses a handle shorter than the lamina (ratio 2.7); the latter displays an anterior membranous alae similar in length to the terminal flagellum, a distal extremity of the left spicule within a simple hook and a membrane, phasmids at the basis of the lappets, and heterogeneous muscles occupying the whole cavity. Dipetalonema yatesi n. sp. can be separated from Dipetalonema robini, Dipetalonema gracile, and Dipetalonema graciliformis, between other characters, in having a simple vagina vera instead of a sinuous one, and from Dipetalonema caudispina and Dipetalonema freitasi in having the lamina of the left spicule divided in a membranous alae and a terminal flagellum.     

Motility of Marichromatium gracile in response to light, oxygen, and sulfide.

The motility of the purple sulfur bacterium Marichromatium gracile was investigated under different light regimes in a gradient capillary setup with opposing oxygen and sulfide gradients. The gradients were quantified with microsensors, while the behavior of swimming cells was studied by video microscopy in combination with a computerized cell tracking system. M. gracile exhibited photokinesis, photophobic responses, and phobic responses toward oxygen and sulfide. The observed migration patterns could be explained solely by the various phobic responses. In the dark, M. gracile formed an approximately 500-microm-thick band at the oxic-anoxic interface, with a sharp border toward the oxic zone always positioned at approximately 10 microM O(2). Flux calculations yielded a molar conversion ratio S(tot)/O(2) of 2.03:1 (S(tot) = [H(2)S] + [HS(-)] + [S(2-)]) for the sulfide oxidation within the band, indicating that in darkness the bacteria oxidized sulfide incompletely to sulfur stored in intracellular sulfur globules. In the light, M. gracile spread into the anoxic zone while still avoiding regions with >10 microM O(2). The cells also preferred low sulfide concentrations if the oxygen was replaced by nitrogen. A light-dark transition experiment demonstrated a dynamic interaction between the chemical gradients and the cell's metabolism. In darkness and anoxia, M. gracile lost its motility after ca. 1 h. In contrast, at oxygen concentrations of >100 microM with no sulfide present the cells remained viable and motile for ca. 3 days both in light and darkness. Oxygen was respired also in the light, but respiration rates were lower than in the dark. Observed aggregation patterns are interpreted as effective protection strategies against high oxygen concentrations and might represent first stages of biofilm formation.     

Rumen Ciliates of Musk-Oxen (Ovibos moschatus Z.) from the Canadian Arctic1

Samples of rumen contents were obtained from 13 musk-oxen living on Banks Island, N.W.T., Canada. Total protozoan numbers ranged from 38.5 to 124.6 times 10⁴ per ml of rumen contents with a mean generic distribution of 52.4%Entodinium, 45.9%Diplodinium, and 1.7%Epidinium. A total of 18 protozoan species were found, six of which have not previously been observed in this host, i.e. D. (Diplodinium) costatum, D. (Ostracodinium) gracile, D. (Ostracodinium) trivesiculatum. D. (Eudiplodinium) medium, Epidinium quadricaudatum, and Epidinium parvicaudatum. Two new species of protozoa are described, Entodinium ovibos n. sp. and Diplodinium (Eudiplodinium) banksi n. sp.     

How different are robust and gracile capuchin monkeys? An argument for the use of sapajus and cebus

Capuchin monkey behavior has been the focus of increasing numbers of captive and field studies in recent years, clarifying behavioral and ecological differences between the two morphological types: the gracile and the robust capuchins (also referred to as untufted and tufted). Studies have tended to focus on the gracile species Cebus capucinus (fewer data are available for C. albifrons, C. olivaceus, and C. kaapori) and on Cebus apella, a name that has encompassed all of the robust capuchins since the 1960s. As a result, it is difficult to ascertain the variation within either gracile or robust types. The phylogenetic relationships between gracile and robust capuchins have also, until now, remained obscure. Recent studies have suggested two independent Pliocene radiations of capuchins stemming from a common ancestor in the Late Miocene, about 6.2 millions of years ago (Ma). The present-day gracile capuchins most likely originated in the Amazon, and the robust capuchins in the Atlantic Forest to the southeast. Sympatry between the two types is explained by a recent expansion of robust capuchins into the Amazon (ca. 400,000 years ago). Morphological data also support a division of capuchins into the same two distinct groups, and we propose the division of capuchin monkeys into two genera, Sapajus Kerr, 1792, for robust capuchins and Cebus Erxleben, 1777, for gracile capuchins, based on a review of extensive morphological, genetic, behavioral, ecological, and biogeographic evidence.     

Effects of dietary vitamin E supplement on gracile axonal dystrophy (gad) mice

We have studied the effects of dietary vitamin E supplement on the clinical signs and pathological changes in GAD (gracile axonal dystrophy) mice. The control diet contained 2 mg of dl-alpha-tocopheryl acetate (2 I.U.) and vitamin E-supplemented diet contained 58.5 mg of dl-alpha-tocopheryl nicotinate (50 I.U.), per 100 mg of feed. The diet was given to normal (gad/+) and GAD (gad/gad) mice from 21 to 130 days of age. During the feeding, there was no improvement in clinical signs in the GAD mice fed the vitamin E-supplemented diet. The gracile nucleus of the medulla oblongata and the gracile fascicules of the spinal cord were investigated for pathology at 130 days of age, and alpha-tocopherol was also assayed in the serum, liver, brain and spinal cord at that time. There were no pathological differences in the gracile nucleus and fascicules between the GAD mice fed the control and vitamin E-supplemented diet. The alpha-tocopherol levels in the serum and target organs in the control GAD mice were not significantly different from those in control normal mice, showing that GAD mice could absorb and transport alpha-tocopherol. In the supplemented GAD mice, no significant increases in alpha-tocopherol levels were observed in the liver, brain or spinal cord. Particularly, the percentage increase of alpha-tocopherol level in the liver of GAD mice was very low in comparison with that in normal mice, even though the liver can store vitamin E. Thus it may be that the capacity to store vitamin E is lowered in GAD mice. Further studies are needed to investigate in detail the vitamin E metabolism in the mutant mice.     

Ecological strategies of Dalbulus leafhoppers

Abstract. 1. Developmental times from egg to adult eclosion were established for eight Dalbulus leafhopper species on maize (Zea mays) and its perennial, gamagrass relative, Tripsacum dactyloides. Experiments were conducted with a 16 h day (25–27°C) and an 8 h night (21–22°C).
2. Developmental times were shortest for the maize specialists, c. 26 days for D. maidis and c. 27 days for D. elimatus, and longest for the Tripsacum specialists, c. 32 days for D. tripsacoides, c. 34 days for D. quinquenotatus and c. 40 days for D. guzmani. Developmental times were intermediate for D. gelbus, D. longulus and D. guevarai, species that utilize both maize and Tripsacum as field hosts.
3. For all species, development was significantly faster on maize (species mean 29 days) than on T. dactyloides (species mean 34 days).
4. D. maidis and D. elimatus developed significantly faster (c. 3 days) on maize than on its close perennial relative, Z. diploperennis.
5. As measured by a 48 h oviposition period, D. maidis, D. elimatus and D. gelbus produced significantly more progeny on maize than on gamagrass. D. quinquenotatus produced more progeny on T. dactyloides than on maize. D. maidis and D. elimatus produced more progeny on maize than on Z. diploperennis.
6. These studies provide support for the hypothesis which predicts that herbivorous insects that specialize on annual plants will have a shorter generation time and be more fecund than perennial specialists. The genus Dalbulus appears to be composed of species that fit an r-K continuum, with maize specialists and Tripsacum specialists at opposite ends of the continuum.     

Effect of water restriction on drinking behaviour and water intake in German black-head mutton sheep and Boer goats

The present study was conducted to evaluate and compare the physiological responses of sheep and goats to water restriction using the deuterium dilution technique (D2O) to predict the total water intake (TWI) in both species. In two consecutive trials, 10 non-lactating Boer goats and 10 non-lactating German black-head mutton ewes were each randomly allocated into a treatment and a control group. In the control groups (n = 5, for each species), water was offered ad libitum, whereas the treatment groups (n = 5, for each species) received water 3 h/day on experimental days 8 to 14 and 6 h every 2 days on experimental days 15 to 22. The respiratory rate, rectal temperature, body mass and drinking behaviour were also recorded. The TWI was estimated by D2O for each animal. Water restriction for 21 h/day or 42 h/2 days had no significant (P > 0.05) effect on water intake (WI), feed intake, WI to dry matter intake ratio or body mass in both species. The absence of differences between species in their WIs was also confirmed using D2O. However, sheep had higher respiratory rates and rectal temperatures than goats in both control and treatment groups. Both species showed the ability to tolerate a moderate water shortage by activating several physiological mechanisms and behavioural strategies.     

Gracile axonal dystrophy (GAD), a new neurological mutant in the mouse

A new neurological mutant has been found in the F2 offspring of CBA/Nga and RFM/Nga mice. Affected mice exhibited ataxia beginning at about 80 days of age, followed by tremor, difficulty in moving, and muscular atrophy of the hind limbs. The neurological signs became progressively severe, and death occurred by 5 to 6 months of age. Since the animals could be distinguished from normal mice by the abnormal positions of the hind limbs when the mouse was hung by the tail after 1 month of age, they could be bred until onset of the signs. Pathological examination revealed neuroaxonal dystrophy and degeneration in the gracile nucleus of the medulla oblongata and the gracile fascicules of the spinal cord, which could be the main cause of the clinical signs. The mutation is inherited as an autosomal recessive trait. It was, therefore, named gracile axonal dystrophy (GAD) with the gene symbol gad. The mice could be a new pathological model for the study of neuroaxonal dystrophy.     

Evolutionary Relationships Among Robust and Gracile Australopiths: An “Evo-devo” Perspective

Hominin fossils of gracile and robust australopith groups were found both in East and in South Africa. It is unclear, however, whether all robusts belong to a monophyletic Paranthropus clade, as the craniofacial resemblance among robust australopiths might only be a superficial correlate of similar masticatory adaptations and not evidence of shared ancestry. It has been suggested that the East African Australopithecus/Paranthropus boisei and the South African A./P. robustus might be convergent allometric variants of their gracile geographical neighbors A. afarensis and A. africanus. Here we approach the phylogenetic questions about robust and gracile australopiths from an ??evo-devo?? perspective, examining how simple alterations of development could contribute to the shape differences among hominin species. Using geometric morphometrics we compare gracile and robust australopith crania in the context of the allometric scaling patterns of Pan troglodytes, P. paniscus, and Gorilla gorilla. We examine support for two alternative evolutionary scenarios based on predictions derived from quantitative genetics models: either (1) A./P. robustus evolved in South Africa from the gracile A. africanus, or (2) A./P. robustus is a local variant of the eastern African A./P. boisei. We use developmental simulations to demonstrate that some robust characteristics (wide faces, anteriorly placed zygomatics, and facial dishing) can be predicted by allometric scaling along the ontogenetic trajectory of the gracile A. africanus. We find, however, that the facial differences between A. africanus specimens (Taung, Sts 5, Sts 71, and Stw 505) and A./P. robustus specimen SK 48 cannot be explained by allometric scaling alone. Facial shape differences between A./P. robustus SK 48 and A./P. boisei (KNM-ER 732, KNM-ER 406, OH 5) and the A./P. aethiopicus specimen KNM-WT 17000, on the other hand, can largely be explained by allometric scaling. This is consistent with a close evolutionary relationship of these robust taxa.     

c-fos Expression in Gracilothalamic Tract Neurons after Electrical Stimulation of the Injured Sciatic Nerve in the Adult Rat

The number of c-fos protein-like immunoreactive (Fos-LI) cells in the gracile nucleus was determined after electrical stimulation at Aα/Aβ-fiber strength of the normal and of the previously injured sciatic nerve in adult rats. No Fos-LI cells were seen after electrical stimulation of the noninjured sciatic nerve, or after sciatic nerve injury without electrical stimulation. However, stimulation 21 days after sciatic nerve transection resulted in numerous Fos-LI cells in the ipsilateral gracile nucleus. Combined Fos immunocytochemistry and retrograde labeling from the thalamus showed that the majority (76%; range = 70–80%) of the cells in the gracile nucleus that expressed Fos-LI after nerve injury projected to the thalamus. The results indicate that morphological, biochemical, and physiological alterations in primary sensory central endings and second-order neurons, which have earlier been demonstrated in the dorsal column nuclei after peripheral nerve injury, are accompanied by changes in the c-fos gene activation pattern after stimulation of the injured sciatic nerve. A substantial number of the c-fos-expressing neurons project to the thalamus.     

Postembryonic development and food consumption of Dichroplus elongatus Giglio-Tos and Dichroplus maculipennis (Blanchard) (Orhtoptera: Acrididae: Melanoplinae) under laboratory conditions

Dichroplus maculipennis (Blanchard) and D. elongatus Giglio-Tos are two of the most important melanoplines in Argentina, both ecologically and economically. The postembryonic development and forage loss (consumption of Bromus brevis Ness + fallen material) caused by older nymphs (instars IV, V, VI) and adults of both species were studied under controlled conditions (30oC, 14L:10D, 40% RH). Five nymphal instars were recorded in D. elongatus, and six in D. maculipennis. Total nymphal development was similar in both species (D. elongatus: 32 ± 0.70 days; D. maculipennis: 34.5 ± 0.37 days). Daily consumption increased from nymphal instars to pre-reproductive adult stage. In both species, pre-reproductive females had higher consumption rates than other stages considered (D. elongatus: 30.6 ± 0.56 mg dry weight/day; D. maculipennis: 48.7 ± 0.74 mg dry weight/day). In the reproductive stage, consumption decreased significantly in both sexes. When feeding, D. maculipennis let some plant material to drop, increasing total loss. The percentage of fallen material was greater in reproductive adults, representing 3.9% and 2.9% of the total daily loss for males and females, respectively. Females and males of D. maculipennis were heavier than those of D. elongatus (P < 0.05), and daily consumption was significantly higher (P < 0.05). Regardless sex and reproductive status, adults of D. maculipennis consumed 29.1 ± 0.64 mg dry weight/day on average, while one of D. elongatus 20.0 ± 0.3 mg dry weight/ day.     

微囊藻对柔细束丝藻生长及土臭素合成与释放的影响

文章选择两种特征不同的微囊藻——产毒的铜绿微囊藻(Microcystis aeruginosa)和无毒的惠氏微囊藻(Microcystis wesenbergii),分别以不同的接种比例(1﹕2、1﹕1和2﹕1)与产土臭素(Geosmin)的柔细束丝藻(Aphanizomenon gracile)混合培养,以探索种间相互作用对藻类生长和束丝藻土臭素合成与释放的影响。结果表明,在共培养条件下,两种微囊藻均抑制了柔细束丝藻的生长,而柔细束丝藻却促进了两种微囊藻的生长。惠氏微囊藻促进了柔细束丝藻土臭素的释放(接种比例为1﹕1时,束丝藻胞外土臭素的细胞份额达到269.43 fg/cell),仅在生长早期与生长受到抑制阶段促进了土臭素的合成;铜绿微囊藻在共培养早期促进了束丝藻土臭素的合成,但共培养却抑制了土臭素的释放,而且在共培养的中后期已检测不到土臭素。研究结果表明,在自然水体中束丝藻与微囊藻的季节演替过程中,微囊藻在与束丝藻的竞争中处于优势,且微囊藻对束丝藻的竞争压力促使后者合成异味物质,随着束丝藻的消亡可能伴随大量异味物质的释放,增加异味事件发生风险。     

浙江天童灌丛植被的土壤种子库与幼苗库特征

采用野外样点取样和萌发实验相结合的办法,研究浙江天童灌丛植被的幼苗库和种子库。结果表明：种子库中优势种类主要是淡竹叶、芒、苔草等草本植物,其次为山矾、Ji木、白栎等灌木种类。在厚度为10cm的表层土壤中,枯枝落叶层、0．2cm层、2－4cm、4－10cm层的种子密度分别为125．0粒／m^2、134．3粒／m^2、84．6粒／m^2、62．7粒/m^2。幼苗库的优势种类不太集中,数量较多的种类有苦槠、紫金牛、淡竹叶等。     

Quantitative analysis of the postnatal axon growth in the dorsal funiculus of rats

The dorsal funiculus in cervical spinal cords of rats from birth to 120 days postnatally has been studied on order to document the axon growth. Within the dorsal funiculus the cuneate and gracile fasciculi have been examined and within the gracile fasciculus the distinct cervical, thoracal and lumbar areas. Light microscopy and morphometry on the day of birth and 15, 20 and 120 days postnatally show an axon growth stagnation between the 15th and 20th day of maturation. The stagnation phase seems to induce the myelinization. A comparison between Goll's and Burdach's tracts shows an earlier and faster growth of the axons in Burdach's tract. Consequently, the epicritical sensibility of the upper extremity is developed earlier. It has been found out that within Goll's tract a caudocranial maturation takes place. The lumbar area of the fasciculus gracilis is matured earlier than the thoracal and the cervical ones.     

Ultrastructural changes in the gracile nucleus of alloxan-induced diabetic rats

The present study reports ultrastructural changes in the gracile nucleus of male Wistar rats after alloxan-induced diabetes. During the acute phase (3-7 days) degenerating electron-dense dendrites and axon terminals were dispersed in the neuropil. Degenerating dendrites were characterized by an electron-dense cytoplasm, swollen mitochondria, dilated endoplasmic reticulum and randomized ribosomes. Degenerating axon terminals were characterized by an electron-dense cytoplasm and clustering of small spherical agranular vesicles. Degenerating axon terminals may form the central element or part of a synaptic glomerulus. Macrophages were present in the neuropil and in the process of engulfing neuronal elements. During the medium phase (1-6 months), most of the degenerating dendrites and axon terminals had been engulfed or removed by macrophages. During the late phase (9-12 months), a second wave of degeneration occurred in the gracile nucleus, similar to the acute phase.     

华山的硅藻

华山是我国名山之一。这里的植物以前很少有人研究,藻类方面,至今未见有人报道。1976年至1982年作者对该地区进行了多次调查采集,现将研究结果报道如下。     

Mapping of the Gracile Axonal Dystrophy (gad) Gene to a Region between D5Mit197 and D5Mit113 on Proximal Mouse Chromosome 5

The gracile axonal dystrophy (gad) mouse, which shows hereditary sensory ataxia and motor paresis, has been morphologically characterized by the dying back type of axonal degeneration in the nerve terminals of dorsal root ganglion cells and motor neurons. In the present study, using an intraspecific backcross between gad and C57BL/6J mice, the gracile axonal dystrophy (gad) gene was mapped to a region between D5Mit197 and D5Mit113. Estimated distances between gad and D5Mit197 and between gad and D5Mit113 are 0.4 ± 0.3 and 5.0 ± 1.0 cM, respectively. The gene order was defined: centromere- D5Mit81-D5Mit233-D5Mit184/D5Mit254-D5Mit256-D5Mit197-gad-D5Mit113-D5Mit7 . The mouse map location of the gad locus appears to be in a region homologous to human 4p15-p16. Our present data suggest that the nearest flanking marker D5Mit197 provides a useful anchor for the isolation of the gad gene in a yeast artificial chromosome contig.     

The energy cost of off-shore migration in Nymphon gracile (Pycnogonida)

The transportation off-shore of the littoral pycnogonid Nymphon gracile during the winter months is facilitated by the ebb tide swimming of this otherwise benthic animal. The energy cost of migration has been estimated from measurements of oxygen consumption and drag forces acting on the different segments of the leg during swimming. The swimming patterns of N. gracile both under constant conditions and in response to tidal pressure cycles are considered in relation to the animals' energy reserves.