Protein histochemistry of the granule cells in the small intestine of the rainbow trout, Salmo gairdneri Richardson

The histochemical nature of the protein within the large granules of the intestinal granule cells was examined in rainbow trout, Salmo gairdneri , from the time of earliest appearance of the cells in the lamina propria until a layer of granule cells was established in 12-month-old juveniles. At all times the granule cell granules contained large quantities of protein. This material appeared to be predominantly cationic in nature as judged from results obtained with alkaline fast green FCF together with deamination controls. In addition, there was no major acidic protein within the intestinal granule cell granules.     

Reproductive strategies of the orang-utan: New data and a reconsideration of existing sociosexual models

Recent field data indicate that MacKinnon’s model of the orang-utan’s sexual and agonistic activity needs to be revised. In this model, male reproductive activity is concentrated in an extended phase of subadulthood and in early adulthood. According to this model, the role of older adult males is primarily that of range guardian, and in that role they would ensure that the offspring they had generated earlier would have safe access to food resources. This study presents cases suggesting that subadult males, even though sexually active, may have low reproductive success. In previous studies adult males were shown to display less sexual initiative than subadult males. In this study an adult male was at times involved infrequent mating activity in response to proceptive activity of females in the course of consortship. This adult male proved to be a successful breeder, thus refuting the hypothesis of adult male sterility. The female is most likely to conceive through cooperative mating in lengthy consortships with the dominant resident adult male. We hypothesize that the extended subadult phase represents a submissive strategy, allowing subadult males to remain in the home range of adult males but with minimal reproductive success.     

Ligation of highly modified bacteriophage DNA

After digestion by TaqI or nicking by DNAase I, five highly modified bacteriophage DNAs were tested as substrates for T4 DNA ligase. The DNAs used were from phages T4, XP12, PBS1, SP82, and SP15, which contain as a major base either glucosylated 5-hydroxymethylcytosine, 5-methylcytosine, uracil, 5-hydroxymethyluracil, or phosphoglucuronated, glucosylated 5-(4′,5′-dihydroxypentyl)uracil, respectively. The relative ability of cohesive-ended TaqI fragments of these DNAs and of normal, λ DNA to be ligated was as follows: $\text{λ}\text{DNA}\text{=}\text{XP}\text{12}\text{DNA}\text{>}\text{SP}\text{82}\text{DNA}\text{?}\text{nonglucosylated}\text{T}\text{4}\text{DNA}\text{>}\text{T}\text{4}\text{DNA}\text{=}\text{PBS}\text{1}\text{DNA}\text{?}\text{SP}\text{15}\text{DNA}$. TaqI-T4 DNA fragments were also inefficiently ligated by Escherichia coli DNA ligase. However, annealing-independent ligation of DNAase I-nicked T4, PBS1, and λ DNAs was equally efficient. We conclude that the poor ligation of TaqI fragments of T4 and PBS1 DNAs was due to the hydroxymethylation (and glucosylation) of cytosine residues at T4's cohesive ends and the substitution of uracil residues for thymine residues adjacent to PBS1's cohesive ends destabilizing the annealing of the restriction fragments. Only SP15 DNA with its negatively charged, modified base was unable to serve as a substrate for T4 DNA ligase in an annealing-independent reaction; therefore, its modification directly interfered with enzyme binding or catalysis.     

Effect of capsaicin on nasal secretion in anesthetized ferrets.

In urethan-anesthetized ferrets, we investigated the nasal response to capsaicin infused via a catheter inserted retrogradely into the lingual artery. Capsaicin dose-dependently increased fluid output from the nose (nasal fluid output) and the lateral nasal gland (glandular fluid output). The secretory response to capsaicin (80 nmol/kg ia) was completely blocked by atropine and hexamethonium, indicating that a cholinergic reflex mediates capsaicin-induced nasal hypersecretion in this model. The amount of nasal secretions collected as nasal fluid output was similar to that collected as glandular fluid output, indicating that the lateral nasal gland contributes significantly to this increase in nasal secretions induced by intra-arterially administered capsaicin. In addition, the nasal fluid output had a higher protein concentration and osmolality than the glandular fluid output. This finding suggests that the gland is not the sole site of action of capsaicin on the nasal secretory response. It is likely that capsaicin also increases microvascular permeability, thereby contributing further to the alteration in the nasal secretions. Finally, repeated subcutaneous injections of capsaicin significantly reduced the secretory response to capsaicin, indicating the development of desensitization in vivo. These results support the role of capsaicin-sensitive sensory nerves in mediating a secretory response in the ferret nose.     

The reproductive biology of female Père David's deer (Elaphurus davidianus)

Data for this study came from breeding records of 27 Père David's (Elaphurus davidianus) hinds maintained in large pastures and from estrous records of four hand-reared nulliparous hinds. The mean estrous cycle length ranged from 17.5 to 19.6 days. Standing estrus resembled that of other cervids, except that a low, moaning vocalization was given in response to contact, and activity (as measured by pedometers) did not increase. Mean gestation length was 183.38 ± SD 6.11 days (n = 21), and nearly all females conceived in the second and third years. The median interbirth interval was 362 days. The median birth date was April 8, and 80% of the births occurred over a 9.5-week period. Multiparous hinds gave birth an average of 20.5 days earlier in the season than primiparous hinds. There was no dimorphism in birth weight. The results are discussed in light of comparative data for other species.     

Selective degradation of insulin within rat liver endosomes

To characterize the role of the endosome in the degradation of insulin in liver, we employed a cell-free system in which the degradation of internalized 125I-insulin within isolated intact endosomes was evaluated. Incubation of endosomes containing internalized 125I-insulin in the cell-free system resulted in a rapid generation of TCA soluble radiolabeled products (t1/2, 6 min). Sephadex G-50 chromatography of radioactivity extracted from endosomes during the incubation showed a time dependent increase in material eluting as radioiodotyrosine. The apparent Vmax of the insulin degrading activity was 4 ng insulin degraded.min-1.mg cell fraction protein-1 and the apparent Km was 60 ng insulin.mg cell fraction protein-1. The endosomal protease(s) was insulin-specific since neither internalized 125I-epidermal growth factor (EGF) nor 125I-prolactin was degraded within isolated endosomes as assessed by TCA precipitation and Sephadex G-50 chromatography. Significant inhibition of degradation was observed after inclusion of p-chloromercuribenzoic acid (PCMB), 1,10-phenanthroline, bacitracin, or 0.1% Triton X-100 into the system. Maximal insulin degradation required the addition of ATP to the cell-free system that resulted in acidification as measured by acridine orange accumulation. Endosomal insulin degradation was inhibited markedly in the presence of pH dissipating agents such as nigericin, monensin, and chloroquine or the proton translocase inhibitors N-ethylmaleimide (NEM) and dicyclohexylcarbodiimide (DCCD). Polyethylene glycol (PEG) precipitation of insulin-receptor complexes revealed that endosomal degradation augmented the dissociation of insulin from its receptor and that dissociated insulin was serving as substrate to the endosomal protease(s). The results suggest that as insulin is internalized it rapidly but incompletely dissociates from its receptor. Dissociated insulin is then degraded by an insulin specific protease(s) leading to further dissociation and degradation.     

The role of litter in an old-field community: impact of litter quantity in different seasons on plant species richness and abundance

Summary We studied the effect of removing and adding plant litter in different seasons on biomass, density, and species richness in a Solidago dominated old-field community in New Jersey, USA. We removed all the naturally accumulated plant litter in November (658 g/m²) and in May (856 g/m²) and doubled the amount of litter in November and May in replicated plots (1 m²). An equal number of plots were left as controls. Litter removal and addition had little impact on total plant biomass or individual species biomass in the growing season following the manipulations. Litter removal, however, significantly increased plant densities but this varied depending upon the season of litter removal, species, and life history type. Specifically, the fall litter removal had a much greater impact than the spring litter removal suggesting that litter has its greatest impact after plant senescence in the fall and prior to major periods of early plant growth in spring. Annual species showed the greatest response, especially early in the growing season. Both spring and fall litter removal significantly increased species richness throughout the study. Litter additions in both spring and fall reduced both plant densities and species richness in June, but these differences disappeared near the end of the growing season in September. We concluded than in productive communities where litter accumulation may be substantial, litter may promote low species richness and plant density. This explanation does not invoke resource competition for the decline in species richness. Finally, we hypothesize that there may be broad thresholds of litter accumulation in different community types that may act to either increase or decrease plant yield and diversity.     

Variability of the opisthaptoral hard parts ofGyrodactylus callariatis Malmberg, 1957 (Monogenea: Gyrodactylidae) from Atlantic codGadus morhua L. in the Oslo Fjord,Norway

The present study describes the variability of the opisthaptoral hard parts ofGyrodactylus callariatis Malmberg, 1957 infesting juvenile Atlantic codGadus morhua L. in the Oslo Fjord, Norway. Samples were taken monthly or bimonthly from January 1993 to July 1994. The length of the 14 characters measured varied considerably throughout the period, and showed a significant regression on the water temperature: as the water temperature increased the length of the hard parts decreased andvice versa. There were no significant differences in the size of the hard parts between young worms (without penis) and older worms (with penis). Some of the characters (especially the anchor shaft) from parasites located on the skin and fins were significantly longer than those of parasites located in the oral cavity, pharynx and gills. Generally, the variation in the shape of the hard parts was small; the anchor root, ventral bar membrane and ventral bar processes were the most variable parts. The shape of the hard parts did not vary as a consequence of seasonal changes in the water temperature, age of the worms or site on the host.