Changes in shoot properties in relation to vertical positions within the crown of mature canopy trees of Abies mariesii and Abies veitchii

We investigated current shoot properties in two contrasting vertical positions (leader crown; LC, and lower branch; LB) within the crowns of mature trees of two subalpine conifer species, Abies mariesii and A. veitchii. For both LCs and LBs, shoot length decreased with increasing branching order. However, shoot properties were different between LCs and LBs. Shoots in LCs had more needle biomass per unit of shoot length. Shoots in sunny conditions pack needles closer along the shoot and intercept incoming light more completely. This causes the shoots in the LCs to have more needles. In contrast, less needle packing per unit shoot length in LBs results in the avoidance of mutual shading among needles in order to intercept limited light more effectively. Because branch systems in lower layers tend to be more shaded, the quantity of irradiance received by the shoots in LBs is smaller. Thus, reduced needle amounts on the shoots in LBs reflect the needle arrangement acclimating to the lower light availability. This study suggests the importance of changes in the properties of individual shoot as a component of a branch system and accordingly a whole-crown system in mature canopy trees of A. mariesii and A. veitchii.     

Effects of undisturbed canopy structure on population structure and species coexistence in an old-growth subalpine forest in central Japan

We investigated structural and compositional characteristics of an old-growth subalpine forest in central Japan, to ascertain forest dynamics and species coexistence. The forest appeared to have been fairly-undisturbed, at least during several recent decades, judging from the maximum occupancy of space by living canopy trees and an unchanged canopy structure between pre- and post-mortality phase. This stable forest showed minimum-scale dynamics that occurred primarily at a single-tree scale. Within this forest, the dominant species were Abies mariesii, A. veitchii and Picea jezoensis var. hondoensis. The two Abies species were abundant and showed advance regeneration, resulting from their high shade-tolerance. On the other hand, Picea showed the greatest basal area, in spite of its lower density. Picea showed steeper initial height-diameter allometric slopes, suggesting that its understorey saplings could increase height more rapidly under sunny conditions. Picea regenerates, given the opportunity of larger disturbances, as approximately even-aged cohorts, and then escapes competition from other shade-tolerant species by attaining the uppermost part of the canopy, resulting from rapid height growth of sapling, longer longevity and emergent attainable height. However, beneath the undisturbed canopy of this forest, in spite of its many seedlings, Picea entirely lacked regenerating individuals, suggesting that its regeneration is in a fairly-limited stage. This suggests that within the undisturbed forest, a demographic trait of Picea, in which the lower mortality of its canopy trees can compensate for its lower recruitment, is not enough to explain its stable coexistence with shade-tolerant Abies spp. Thus, not only the demographic trait, but also the spatial/temporal disturbance magnitude is important for an explanation of the coexistence of Picea with Abies. Consequently, it seems that not only equilibrium process, such as species differences in life-history traits, but also non-equilibrium process, such as disturbances, is crucial for their coexistence in this subalpine forest in central Japan.     

Light-related competitive effects of overstory trees on the understory conifer saplings in a subalpine forest

To clarify the mechanism by which overstory trees shade understory saplings, we investigated the relationships among light conditions of the saplings (measured as indirect site factor; ISF and direct site factor; DSF), the calculated competition effects of overstory trees on the saplings (W), and relative height growth rate of the saplings (RHGR). We calculated several W values in order to find a W value which can express the light conditions as appropriately as possible, and the results indicated that W explained only 21.9%–24.7% of the total variance of light conditions in the cases where W gave the best fit. In this study, W was calculated based on the basal areas of overstory trees. However, it is known that canopy structure also affects the light regimes in the forest understory, and this might yield the possible errors even within W representing the shading effects most adequately. Therefore, although W significantly represents the shading effect from overstory trees, a great proportion of the variance remained without being explained by W. RHGR was negatively correlated with W, and the W value which had the most adequate explanation of the shading effect also showed the best negative correlation with RHGR. This provides the evidence that the competitive effect of overstory trees on sapling growth is mediated by the shading effect, indicating that competition for light clearly exists within this forest. Such competition for light may closely relate to the well-known phenomenon of gap regeneration in subalpine forests in central Japan.     

Acid-base and biochemical stabilization and quality of recovery in male cats with urethral obstruction and anesthetized with propofol or a combination of ketamine and diazepam

This study compared acid-base and biochemical changes and quality of recovery in male cats with experimentally induced urethral obstruction and anesthetized with either propofol or a combination of ketamine and diazepam for urethral catheterization. Ten male cats with urethral obstruction were enrolled for urethral catheterization and anesthetized with either ketamine-diazepam (KD) or propofol (P). Lactated Ringer’s solution was administered by intravenous (IV) beginning 15 min before and continuing for 48 h after relief of urethral obstruction. Quality of recovery and time to standing were evaluated. The urethral catheter was maintained to measure urinary output. Hematocrit (Hct), total plasma protein (TPP), albumin, total protein (TP), blood urea nitrogen (BUN), creatinine, pH, bicarbonate (HCO₃⁻), chloride, base excess, anion gap, sodium, potassium, and partial pressure of carbon dioxide in mixed venous blood (pvCO₂) were measured before urethral obstruction, at start of fluid therapy (0 h), and at subsequent intervals. The quality of recovery and time to standing were respectively 4 and 75 min in the KD group and 5 and 16 min in the P group. The blood urea nitrogen values were increased at 0, 2, and 8 h in both groups. Serum creatinine increased at 0 and 2 h in cats administered KD and at 0, 2, and 8 h in cats receiving P, although the values were above the reference range in both groups until 8 h. Acidosis occurred for up to 2 h in both groups. Acid-base and biochemical stabilization were similar in cats anesthetized with propofol or with ketamine-diazepam. Cats that received propofol recovered much faster, but the ketamine-diazepam combination was shown to be more advantageous when treating uncooperative cats as it can be administered by intramuscular (IM) injection.     

Male rats respond to their own alarm pheromone

Pheromones are defined as substances released from an individual (donor) that influence a second individual (recipient) of the same species. However, it is unclear whether mammalian pheromones can affect the donor itself. To address this question, the effect of self-exposure to an alarm pheromone was examined. Exposure to the alarm pheromone resulted in an enhanced anxiety response, which was not different between recipients that perceived their own pheromone and those that perceived another individual's pheromone. The present results suggest that the alarm pheromone influences the emotional system of the recipient as well as induces similar anxiogenic effects on the donor rat that released the alarm pheromone. This is the first evidence demonstrating the effectiveness of mammalian pheromone self-exposure.     

Fascin‐1 expression in canine cutaneous and oral melanocytic tumours

Fascin‐1 expression was examined in 9 cutaneous melanocytomas and 47 oral melanomas. The cases were scored on the basis of extent and intensity of staining, and combined scores were calculated. Fascin‐1 expression was observed in 5/9 (56%) melanocytomas and 46/47 (98%) melanomas. The combined score for fascin‐1 was significantly greater in stage III/IV melanomas than in stage I/II melanomas (P < 0.05). In addition, strong fascin‐1 staining was associated with a significantly shortened survival time (P < 0.05). The results of this study suggest that fascin‐1 overexpression correlates with the malignancy of canine melanoma and has the potential to be a new immunohistochemical marker to predict the clinical course of canine melanoma. In addition, targeted therapy for fascin‐1 may represent a new strategy for the treatment of canine melanoma.     

Decreased gene expression of insulin signaling genes in insulin sensitive tissues of obese cats

Type 2 diabetes mellitus (DM) animal models have provided ample opportunity for investigating pathogenesis, as well as to evaluate novel treatment and prevention options for the disease. Because the domestic cat shares a similar environment with humans, it is also confronted with many similar risk factors for diabetes, such as physical inactivity and obesity. Obesity is a significant risk factor for diabetes in cats, and as such, the domestic cat may serve as an ideal model for investigating obesity induced insulin resistance. This study determined changes in insulin signaling genes within insulin sensitive tissues of obese felines. Quantitative RT-PCR was performed to determine mRNA levels of three important insulin signaling genes which have been implicated with insulin resistance: insulin receptor substrate (IRS)-1, IRS-2, and phosphatidylinositol 3’-kinase (PI3-K) p85α. Obese cats had significantly lower IRS-2 and PI3-K p85α mRNA levels in liver and skeletal muscle as compared to control cats. This down regulation of insulin signaling genes in obese cats mirrors that of obese humans and rodents suffering from insulin resistance. Interestingly, preprandial blood tests indicated that our obese cats were no different from control cats with regards to glucose tolerance and insulin resistance, thus indicating that the obese cats used in our study had a moderate level of obesity. Therefore, insulin signaling gene alterations were occurring in insulin sensitive tissues of moderately obese felines before glucose intolerance was clinically evident. As such, the monitoring of key insulin signaling genes may have some important diagnostic value to determine the risk level and degree of obesity induced insulin resistance.     

Clinical significance of plasma mannose concentrations in healthy and diabetic dogs

Circulating levels of monosaccharides can act as a reflection of systemic glucose/ energy metabolism. Characteristic changes observed in these levels can be seen in patients with diabetes and other metabolic disorders. There have been a few reports describing the significance of mannose metabolism as an energy source under physiological and pathological conditions. However, the relationship between circulating levels of mannose and the pathophysiology of diabetes mellitus are unknown in dogs. This study examined circulating levels of mannose between healthy control and diabetic dogs and evaluated the clinical significance of mannose levels in dogs. Diabetic dogs demonstrated a higher circulating level of mannose in comparison to normal healthy control dogs. Plasma mannose was positively correlated with plasma glucose and fructosamine, respectively. Interestingly, plasma mannose levels were affected by plasma insulin levels. In the context of feeding and glucose tolerance tests, plasma mannose levels responded to changes in circulating insulin levels. Circulating plasma mannose levels decreased after feeding in both control and diabetic animals in spite of observed insulin level differences. However, when glucose tolerance tests were given, a positive correlation between mannose levels and insulin levels was observed. Therefore, plasma mannose levels obtained via glucose tolerance testing may be used as a new diagnostic method for evaluating insulin resistance or deficiency in diabetic dogs.