Interdependence of Cell Cycle Events in Tetrahymena thermophila: Formation of Contractile Vacuole Pore and Fission Gap in Ciliary Meridians*

SYNOPSIS The formation of the contractile vacuole pore (CVP) in Tetrahymena thermophila. genotype mol^b/mol^b is temporally and spatially associated with the formation of the fission gap in the CVP meridian. New CVPs arise when fission gaps appear in CVP meridians, the new pores being found anterior to the gaps. When, however, CVP meridians are rotated 180°, the fission gaps develop late. In more than 1/3 of the 180°-rotated CVP meridians, the new CVPs are formed before the appearance of the fission gap. Evidently, the appearance of the gap is not a prerequisite for CVP formation. Nevertheless, mutants exist in which the absence of fission gap and CVP are correlated in some cases and in which the presence of supernumerary fission gap and CVP are correlated in other instances. It is suggested that the 2 developmental events, although not causally related to each other, may be controlled by a common morpho-genetic signal. This commits a certain site (mid-body) along a ciliary meridian to develop the fission gap as well as the CVP; however, after this step of commitment, the appearance of the fission gap is delayed in 180°-rotated CVP meridians.     

Human gastrointestinal epithelia of the esophagus,stomach, and duodenum resolved at single-cell resolution

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Comparison of lower limb kinetics,kinematics and muscle activation during drop jumping under shod and barefoot conditions

This study was to investigate the acute effects of wearing shoes on lower limb kinetics, kinematics and muscle activation during a drop jump. Eighteen healthy men performed a drop jump under barefoot and shod conditions. Vertical ground reaction force (GRF) was measured on a force plate during the contact phase of a drop jump, and GRF valuables were calculated for each condition. The angles of the knee and ankle joints, and the foot strike angle (the angle between the plantar surface of the foot and the ground during ground contact) as well as the electromyography of 7 muscles were measured. The shod condition showed a significant larger first peak GRF, longer time to first peak GRF from the initial ground contact and lower initial loading rate than the barefoot condition. The shod condition showed a significant larger ankle joint angle at initial ground contact, smaller knee joint angle between the second peak GRF and take-off as well as smaller foot strike angle at both initial ground contact and take-off than the barefoot condition. There were significant correlations between relative differences in ankle joint at the initial ground contact and relative differences in the initial loading rate. The muscle activity of all muscles during foot ground contact did not differ between two conditions; however, in the shod condition, muscle activation of 150 ms before foot ground contact was significantly higher in the rectus femoris, whereas it was lower in the biceps femoris and tibialis anterior muscles than the barefoot condition. These results indicate that wearing shoes alternates the GRF variables at initial ground contact, joint kinematics at the ground contact and muscle activation before foot ground contact during a drop jump, suggesting that the effects of wearing shoes on drop jump training differ from being barefoot.     

The nature of the primate grasping foot

The grasping primate foot is one of the hallmark adaptations for the order Primates. Prosimian muscle and joint analysis indicates that there are two distinct primate grasping feet. The I–V opposable grasp, in which the hallux opposes the other four digits around a support, is the primitive grasp type utilized by cheirogaleids, lorisides, Daubentonia, and tarsiids. Lemurids and indriids, on the other hand, have a derived I–II adductor grasp, where the grasping action of the hallux and the second digit have been enhanced. This grasp seems to be in response to increasing body size and the use of vertical supports. North American adapids, which were large and possessed the I–V opposable grasp, were probably not able to utilize vertical supports frequently. The recognition of this innovative adaptation, the I–II adductor grasp, which is unique to Madagascar, extends our appreciation of prosimian locomotor capabilities.     

Advanced gastric carcinoma in a de Brazza's guenon (Cercopithecus neglectus)

Abstract: A necropsy case of advanced gastric carcinoma in a 20-year-old female de Brazza's guenon (Cercopithecus neglectus) was studied. Grossly, an excavated carcinoma mass, 60 × 55 × 35 mm in size, was located in the cardiac region of the stomach. Multiple disseminated nodules had implanted on the diaphragm and omentum. The tumor consisted of intestinal-type adenocarcinoma cells and showed infiltrative growth beyond the serosa. The morphologic features of this tumor closely resembled those of advanced gastric carcinomas in human patients.     

The activity front of the migrating motor complex of the human stomach but not of the small intestine is motilin-dependent

The role of motilin in the generation of the gastric component of phase 3 of the migrating myoelectric complex (MMC) was studied in human volunteers. Interdigestive motor activity was recorded manometrically in five normal subjects after a fast of at least 15 h. Intraluminal pressures were measured in the gastric antrum at 4 levels 3 cm apart and in the upper small bowel at 3 levels 25 cm apart. Blood samples were drawn every 10 min for radioimmunoassay of motilin and PP. After 2 spontaneously occurring activity fronts (AF) had been recorded, bovine PP was infused intravenously at a rate of 50 μg/h. Following the third AF a combination of PP (50 μg/h) and 13-norleucine-motilin (30 μg/h) was infused until after the next AF. It was found that 90% of the spontaneous AFs originated in the stomach. They were preceded by a motilin peak. During the PP infusion, plasma PP levels increased from 29 to 256 pmol/l, motilin decreased from 42 to 15 pmol/l, and all AFs originated in the small bowel. During the combined PP and motilin infusion, plasma motilin increased to 330 pmol/l, and all AFs again originated in the stomach. It is concluded that motilin has an important role in the regulation of the MMC activity front in the stomach, but not in the small intestine. Postprandial rises in plasma PP might be involved in lowering motilin levels after a meal, and indirectly, in the disruption of gastric MMCs during digestion.     

Neuromuscular response of hip-spanning and low back muscles to medio-lateral foot center of pressure manipulation during gait

Background: Footwear-generated medio-lateral foot center of pressure manipulation has been shown to have potential positive effects on gait parameters of hip osteoarthritis patients, ultimately reducing maximum joint reaction forces. The objective of this study was to investigate effects of medio-lateral foot center of pressure manipulation on muscle activity of hip-spanning and back muscles during gait in bilateral hip osteoarthritis patients. Methods: Foot center of pressure was shifted along the medio-lateral foot axis using a foot-worn biomechanical device allowing controlled center of pressure manipulation. Sixteen female bilateral hip osteoarthritis patients underwent electromyography analysis while walking in the device set to three parasagittal configurations: neutral (control), medial, and lateral. Seven hip-spanning muscles (Gluteus Medius, Gluteus Maximus, Tensor Fascia Latae, Rectus Femoris, Semitendinosis, Biceps Femoris, Adductor Magnus) and one back muscle (Erector Spinae) were analyzed. Magnitude and temporal parameters were calculated. Results: The amplitude and temporal parameter varied significantly between foot center of pressure positions for 5 out of 8 muscles each for either the more or less symptomatic leg in at least one subphase of the gait cycle. Conclusion: Medio-lateral foot center of pressure manipulation significantly affects neuromuscular pattern of hip and back musculature during gait in female hip bilateral osteoarthritis patients.     

Ultrastructural and immunohistochemical demonstration of pancreatic polypeptide-containing F-cells in the stomach and pancreas of Tupaia belangeri

The gastro-entero-pancreatic (GEP) system in Tupaia belangeri contains a specific cell which reacts with antisera to pancreatic polypeptide (PP). The cells are scattered between exocrine pancreatic cells and also found in the pancreatic islets. Furthermore, they are also located in the fundic glands and to a very small extent in the corpus mucosa and in the glands of the upper duodenum. The cell reacting with antisera against PP is identified as the F-cell which has a specific ultrastructure especially with respect to its secretion. The present identification of the F-cell as the PP-cell in pancreas and stomach is discussed with respect to its possible functional implications.     

Evidence for insectivory in two primate species (Callicebus torquatus lugens and Lagothrix lagothricha lagothricha) from northwestern Amazonia

Insects were recovered and identified from stomach contents of two Callicebus torquatus lugens and one Lagothrix lagothricha lagothricha collected in a remote area of northwestern Amazonia. Both C. torquatus lugens showed little insect matter in stomach contents. Conversely, a minimum of 133 individual insects were recovered from stomach contents of the L. lagothricha lagothricha. These included various larger, rapid forms (Cicadellidae) unlikely to have been inadvertently consumed while the animal was eating fruit.