Histochemical observations on the crown skin of male baya: Lipids,lipase and phosphomonoesterases

Histochemical studies on localisation of lipids, lipase and phosphomonoeste-rases in the crown skin of male baya during non-breeding and breeding seasons were carried out. The results indicated a high turnover rate for lipid synthesis and its utilisation, increased acid and alkaline phosphatase activities in the crown skin of breeding male baya as compared to that in non-breeding season. It is surmised that crown skin of male baya becomes metabolically hyperactive during breeding season aiding processes such as cell growth and proliferation, keratinization and production of coloured feathers related to breeding.     

Studies on the striatal dopamine uptake system of weaver mutant mice and effects of ventral mesencephalic grafts

The dopamine (DA) uptake system was investigated in the mesostriatal system of normal and weaver mutant mice, which lose mesencephalic DA neurons, as well as in weaver mutants with ventral mesencephalic grafts to the striatum. Assays of [³H]DA uptake in striatal synaptosomal fractions in vitro and autoradiography of [³H]mazindol binding in brain sections were carried out in wild-type mice (+/+) and in the two hemispheres of homozygous weaver mutants (wv/wv) that had received unilateral grafts of mesencephalic cell suspensions to the right side. Net [³H]DA uptake, expressed as pmol/mg-protein/2-min, was on the average 50.6 in the striatum of wild-type mice, 7.9 in the non-grafted, and 10.1 in the transplanted striatum of weaver mutants. [³]DA uptake in wild-type mice differed significantly from both the grafted and non-grafted weaver striata (P<0.001). Paired comparisons for [³H]DA uptake between right and left sides of recipient weaver mice showed a significant side effect (P<0.02), the right side being 28–38% higher than the left side [mean of all individual (R-L)/L values]. The results of amphetamine-induced turning behavior tests were compared with the biochemical findings. Mice with grafts to the right side rotated an average of 22 turns to the left and 7 turns to the right during the five one-minute sessions; the mean value L/(L+R) was 64%. A plot of (L-R) rotations against (R-L) [³H]DA uptake gave a correlation coefficient of 0.552 (P<0.05), indicating that animals with a strong rotational bias to the left tended to have higher [³H]DA on the right. Similarly, the animals that were used for [³H]mazindol binding autoradiographic studies displayed on the average 72% rotations to the left side. In the [³H]mazindol binding data, non-grafted weaver mutants showed the severest depletion relative to wild-type in the dorsomedial and dorsolateral caudate-putamen (86% and 87%, respectively). Mice with unilateral grafts to the right side showed an increase in [³H]mazindol binding signal in the transplanted side of 40–64% (depending on dorsoventral topography) over the contralateral, non-grafted side. These findings attest to the functional effects of the grafts at the anatomical, biochemical, and behavioral levels. The parallel measurements of motor performance and DA uptake in the same animals offers an index of behavioral recovery as a function of transmitter-related activity. Furthermore, by conducting measurements of the synaptosomal DA uptake in vitro and of the binding characteristics of mazindol in brain slices by autoradiography, one has the advantage of combining the anatomical resolution of uptake site visualization with a dynamic indicator of function for DA uptake in the nerve terminal.Special issue dedicated to Professor Sidney Ochs     

The weaver mutant mouse as a model of nigrostriatal dysfunction

The weaver mutant mouse has a genetic defect that results in the loss of dopamine neurons in the nigrostriatal pathway. Striatal tyrosine hydroxylase and dopamine content are reduced by 60–70%, and dopamine uptake is reduced by as much as 95%. Deficits in all three of these striatal dopamine markers are seen as early as postnatal d 3. The striatal dopamine systems in the weaver apparently have the ability to compensate for this dopamine deficit. Thus, in the weaver, in vitro resting release, as well as amphetamine-evoked fractional release of endogenous dopamine are increased. An additional change seen in the weaver striatum is an elevated serotonin content. These alterations may play an adaptive role in attempting to compensate for the dopamine loss. In summary, the weaver mutant mouse has dramatic deficits in the nigrostriatal pathway, but also seems to develop certain adaptive mechanisms in dopaminergic and other transmitter systems that may compensate functionally for the dopamine deficit. Thus, the weaver mouse provides a unique animal model for studying naturally induced neuronal degeneration that complements those models using surgical and pharmacological protocols.     

Coenzyme Q10 inhibits mitochondrial complex-1 down-regulation and nuclear factor-kappa B activation

We have used control-homozygous weaver mutant, and -heterozygous weaver mutant mice in order to explore the basic molecular mechanism of neurodegeneration and the neuroprotective potential of coenzyme Q(10). Homozygous weaver mutant mice exhibited progressive neurodegeneration in the hippocampus, striatum, and cerebellum, and a reduction in the striatal levels of dopamine and coenzyme Qs (Q(9) and Q(10)) without any significant changes in norepinephrine and serotonin. Mitochondrial complex-1 was down regulated; whereas nuclear factor-kappa B was up regulated in homozygous weaver mutant mice. Rotenone inhibited complex-1, enhanced nuclear factor-kappa B, and caused apoptosis in human dopaminergic (SK-N-SH) neurons; whereas nuclear factor-kappa B antibody suppressed rotenone-induced apoptosis, suggesting that enhancing coenzyme Q(10) synthesis and suppressing the induction of NF-kappa B, may provide neuroprotection.     

奶牛微卫星基因座与产奶性能关系的研究

根据小鼠与牛的遗传比较图谱及相关报道选择了与weaver基因连锁的7个微卫星基因库,并在荷斯坦牛群体中对这些基因座进行群体遗传学特性分析。选择具有中度以上多态性的4个微卫星基因座（BM6438、BMS2321、BMS711和TGLA116）进行产奶性能的相关分析。最小二乘分析结果表明,4个微卫星基因座对产奶量影响不显著（P＞0．05）,BM6438生BMS711基因座对乳成分影响不显著（P＞0．05）,BMS2321基因座对乳蛋白量和乳蛋白率有极显著的影响（P＜0．01）,TGLA116对乳蛋白量和乳蛋白率的影响达到0．05的显著水平。     

Song differences between populations of seven subspecies of the African forest weaver Ploceus bicolor Vieillot (Aves: Passeriformes)

We present an analysis of song type differences between populations of seven forest weaver (Ploceus bicolor) subspecies. Phonology and syntax of the melodious parts of song types differ between these populations to the same extent as they differ between population-specific dialects within a subspecies. Phonological and syntactical song features are socially transmitted; they can be transmitted even between representatives of taxonomically different subspecies. The Harsh Call, a complex element embedded in the melody, is of similar structure in populations of four South African subspecies, but shows markedly different characteristics in populations of the subspecies from Kenya and Cameroon. Song differences between populations are suggested to result from cultural drift and geographic isolation. A correspondence between genetically determined morphological structures on the one hand and socially transmitted song structure on the other seems to be a coincidence due to geographic separation.     

Comparison of alterations in tyrosine hydroxylase,dopamine levels,and dopamine uptake in the striatum of the weaver mutant mouse

Previous reports have shown that among the markers for the nigro-striatal dopamine (DA) system measured in the striatum, dopamine uptake seems to be more severely affected than the others in the weaver mutant mouse. In the present study we examined DA levels, tyrosine hydroxylase (TH) activity, and high-affinity DA uptake to determine if the DA uptake is most affected when all the measurements are made in the same striatal homogenate in the same laboratory. We found that the DA uptake activity was most altered (93% lower) compared to DA levels (68% lower) and TH activity (64% lower). The DA uptake was so low in the weaver that we could not obtain reliable kinetic parameters. For TH activity we found that the Vmax was 36% lower while the Km forl-tyrosine was 92% higher in the weaver striatum. This lower affinity for substrate suggests that the TH enzyme itself may be altered in the nigro-striatal system of the weaver mutant mouse.Special issue dedicated to Dr. Morris H. Aprison.     

Effect of differential photostimulation on induction of Fos-like immune-reactivity in the MBH region of Indian weaver bird

This study investigated the neuronal activation (c-fos) in the mediobasal hypothalamus (MBH) of the Indian weaver bird, after exposure to a single long-day. Wild-caught photosensitive birds were exposed to the short-days (LD 8L:16D). After four days of short-days photoperiod, the LD cycle was programmed such that the light illumination was continuous after zeitgeber time (ZT) 8. Birds were perfused on the same day at ZT 4 or ZT 20. Brains were processed for the immunohistochemistry of c-fos (Fos) in the MBH. We found a significant higher activation of Fos in neurons within the ventral tuberal division (containing infundibular nucleus) of the MBH, in group that received 20-h light than that received 4-h light on first long-day. But in the dorsal tuberal division, there was no noticeable difference in Fos-lir activation on after 4-h and 24-h light exposure. The results suggest that the ventral tuberal division of mediobasal hypothalamus is principally involved in detecting the photoperiodic information from the external environment, and hence, suggested as the key neural center, involved in the photoperiodic mechanism in Indian weaver bird.     

Circadian and Seasonal Responses in Indian Weaver Bird: Subjective Interpretation of Day and Night Depends Upon Both Light Intensity and Contrast Between Illuminations

This study investigated whether changes in illumination modify perception of day and night conditions in a diurnal species, the Indian weaver bird. Birds were initially subjected to a 12-h light:12-h dark regime (12L:12D; L?=?20 lux, D =?0.5 lux). After every 2 wks, the combinations of light illumination in L and D phases were changed as follows: 20:2 lux, 20:5 lux, 20:10 lux, 20:20 lux, 20:100 lux, and 20:200 lux. Finally, birds were released into dim constant light (0.5 lux) for 2 wks to determine the phase and period of the circadian activity rhythm. They were also laparotomized at periodic intervals to examine the effects of the light regimes on the seasonal testicular cycle. All individuals showed a consistently similar response. As evident by the activity pattern under these light regimes, both in total activity during contrasting light phases and during the 2?h in the beginning and end of first light phase, birds interpreted the period of higher light intensity as day, and the period of lower intensity as the night. During the period of similar light intensity, i.e., under LL, birds free-ran with a circadian period (～24?h). In bright LL (20 lux), the activity rhythm was less distinct, but periodogram analysis revealed the circadian period for the group as 24.46?±?0.41?h (mean?±?SE). However, in dim LL at the end of the experiment, all birds exhibited a circadian pattern with average period of 25.52?±?0.70?h. All birds also showed testicular growth and regression during the 16-wks study. It is suggested that weaver birds interpret day and night subjectively based on both the light intensity and contrast between illuminations during two phases over the 24?h. (Author correspondence: drskumar7@yahoo.com)