Search Results (12)

Orphaned colonies of Cryptotermes domesticus readily produce replacement reproductives and continue propagation. In this study, we aimed to investigate the production and fecundity of neotenic reproductives in 5-year-old colonies of C. domesticus after orphaning. All 15 experimental colonies were successfully re-established by the neotenic reproductive pair. Three types of neotenic reproductives with various wing-bud lengths were observed: type I with micro wing buds, type II with short wing buds, and type III with long wing buds. Four patterns of pairs made up of these neotenics, namely, type I + type II, type I + type III, type II + type II, and type II + type III, exhibited reproductive capacities similar to those of the primary reproductive pair. We speculated that these neotenic reproductives were derived from various nymphal instars. The 5-year-old colonies had three instars of nymphs, with the majority being in the second instar, followed by the first. Thus, the combination of neotenic reproductives with short wing buds and micro wing buds was the dominant differentiation pathway of the orphaned colonies. After the removal of the original primary reproductive pair, the nymphs matured into neotenic reproductives and took over reproduction in the colony in 107.40 ± 15.18 days. This study highlights the importance of quarantine and routine inspection of wood, as well as the significance of early prevention and control of C. domesticus infestation in wood. Moreover, this study confirms the high differentiation and reproductive capacities of C. domesticus. Full article

The domestication of humans is not an issue of domesticity but of the effects of the domestication syndrome on a hominin species and its genome. These effects are well expressed in the ‘anatomically modern humans’, in their physiology, behavior, genetic defects, neuropathology, and distinctive neoteny. The physiological differences between modern (gracile) humans and their ancestors, robust Homo sapiens types, are all accounted for by the domestication syndrome. From deductions we can draw about early human behavior, it appears that modifications are attributable to the same cause. The domestication hypothesis ascribes the initiation of the changes to selective breeding introduced by the consistent selection of neotenous features. That would trigger genetic pleiotropy, causing the changes that are observed. Full article

The transplantation of neural progenitors into a host brain represents a useful tool to evaluate the involvement of cell-autonomous processes and host local cues in the regulation of neuronal differentiation during the development of the mammalian brain. Human brain development starts at the embryonic stages, in utero, with unique properties at its neotenic stages. We analyzed the engraftment and differentiation of human neuronal progenitor cells (hNPCs) transplanted in utero into the mouse brain. The influence of the environment was studied by transplanting human NPCs within the lateral ventricles (LV), compared with the prefrontal cortex (PFC) of immunocompetent mice. We developed a semi-automated method to accurately quantify the number of cell bodies and the distribution of neuronal projections among the different mouse brain structures, at 1 and 3 months post-transplantation (MPT). Our data show that human NPCs can differentiate between immature “juvenile” neurons and more mature pyramidal cells in a reproducible manner. Depending on the injection site, LV vs. PFC, specific fetal local environments could modify the synaptogenesis processes while maintaining human neoteny. The use of immunocompetent mice as host species allows us to investigate further neuropathological conditions making use of all of the engineered mouse models already available. Full article

Jurasaidae are a family of neotenic elateroid beetles which was described recently from the Brazilian Atlantic Forest biodiversity hotspot based on three species in two genera. All life stages live in the soil, including the larviform females, and only adult males are able to fly. Here, we report the discovery of two new species, Jurasai miraculum sp. nov. and J. vanini sp. nov., and a new, morphologically remarkable population of J. digitusdei Rosa et al., 2020. Our discovery sheds further light on the diversity and biogeography of the group. Most species of Jurasaidae are known from the rainforest remnants of the Atlantic Forest, but here for the first time we report a jurasaid species from the relatively drier Atlantic Forest/Caatinga transitional zone. Considering our recent findings, minute body size and cryptic lifestyle of all jurasaids, together with potentially high numbers of yet undescribed species of this family from the Atlantic Forest and possibly also other surrounding ecoregions, we call for both field research in potentially suitable localities as well as for a detailed investigation of a massive amount of already collected but still unprocessed materials deposited in a number of Brazilian institutes, laboratories and collections. Full article

Plants in the family Lemnaceae are aquatic monocots and the smallest, simplest, and fastest growing angiosperms. Their small size, the smallest family member is 0.5 mm and the largest is 2.0 cm, as well as their diverse morphologies make these plants ideal for laboratory studies. Their rapid growth rate is partially due to the family’s neotenous lifestyle, where instead of maturing and producing flowers, the plants remain in a juvenile state and continuously bud asexually. Maturation and flowering in the wild are rare in most family members. To promote further research on these unique plants, we have optimized laboratory flowering protocols for 3 of the 5 genera: Spirodela; Lemna; and Wolffia in the Lemnaceae. Duckweeds were widely used in the past for research on flowering, hormone and amino acid biosynthesis, the photosynthetic apparatus, and phytoremediation due to their aqueous lifestyle and ease of aseptic culture. There is a recent renaissance in interest in growing these plants as non-lignified biomass sources for fuel production, and as a resource-efficient complete protein source. The genome sequences of several Lemnaceae family members have become available, providing a foundation for genetic improvement of these plants as crops. The protocols for maximizing flowering described herein are based on screens testing daylength, a variety of media, supplementation with salicylic acid or ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (EDDHA), as well as various culture vessels for effects on flowering of verified Lemnaceae strains available from the Rutgers Duckweed Stock Cooperative. Full article

In eusocial insects (e.g., ants, bees, and termites), the roles of different castes are assigned to different individuals. These castes possess unique phenotypes that are specialized for specific tasks. The acquisition of sterile individuals with specific roles is considered a requirement for social evolution. In termites, the soldier is a sterile caste. In primitive taxa (family Archotermopsidae and Stolotermitidae), however, secondary reproductives (neotenic reproductives) with their mandibles developed into weapons (so-called reproductive soldiers, also termed as soldier-headed reproductives or soldier neotenics) have been reported. To understand the developmental mechanism of this unique caste, it is necessary to understand the environmental cues and developmental processes of reproductive soldiers under natural conditions. Here, we established efficient conditions to induce reproductive soldiers in Zootermopsis nevadensis. Male reproductive soldiers frequently developed after the removal of both the king and soldiers from an incipient colony. Similarly, high differentiation rates of male reproductive soldiers were observed after king-and-soldier separation treatment using wire mesh. However, no male reproductive soldiers were produced without direct interaction with the queen. These results suggest that male reproductive soldier development is repressed by direct physical interactions with both the king and soldiers and facilitated by direct physical interaction with the queen. Full article

Coptotermes gestroi is a subterranean termite with colonies generally headed by a pair of primary reproductives, although neotenics may occur. In this study, the male reproductive system was compared during different life stages of nymphs, alates, neotenic reproductives, and kings of C. gestroi, focusing on the modifications of this system along the maturation of these individuals. The structure of the male reproductive system follows the pattern described for insects, although C. gestroi males do not exhibit conspicuous penises and differentiated accessory glands. In kings, each testis consisted of about seven lobes, significantly increased in size as compared to younger males. The spermatogenesis begins in third-instar nymphs, which already presented spermatozoa in the testes. The seminal vesicles are individualized in C. gestroi and have a secretory distal portion and a proximal portion with a role in spermatozoa storage. The secretion of the seminal vesicles is strongly periodic acid Schiff (PAS)-positive, whereas the xylidine Ponceau test revealed proteins that increase in quantity while the males become older. This is the first record of glycoproteins in the lumen of seminal vesicles in termites. Further studies will clarify how they are produced and interact in the physiology and nutrition of the non-flagellate spermatozoa of C. gestroi. Full article

Termites are social insects that live in colonies headed by reproductive castes. The breeding system is defined by the number of reproductive individuals in a colony and the castes to which they belong. There is tremendous variation in the breeding system of termites both within and among species. The current state of our understanding of termite breeding systems is reviewed. Most termite colonies are founded by a primary (alate-derived) king and queen who mate and produce the other colony members. In some species, colonies continue throughout their life span as simple families headed by the original king and queen. In others, the primary king and queen are replaced by numerous neotenic (nymph- or worker-derived) reproductives, or less commonly primary reproductives, that are descendants of the original founding pair leading to inbreeding in the colony. In still others, colonies can have multiple unrelated reproductives due to either founding the colonies as groups or through colony fusion. More recently, parthenogenetic reproduction has shown to be important in some termite species and may be widespread. A major challenge in termite biology is to understand the ecological and evolutionary factors driving the variation in termite breeding systems. Full article

In this study, the ultrastructure of mitochondria in cardiomyocytes of naked mole rats (Heterocephalus glaber) aged from 6 months to 11 years was examined. Mitochondria in cardiomyocytes of naked mole rats have a specific ultrastructure that is different from those in cardiomyocytes of other mammalian species studied to date. In contrast to mitochondria of other mammalian cardiomyocytes, where the internal space is completely filled by tightly packed parallel rows of cristae, mitochondria in cardiomyocytes of naked mole rats have a chaotic pattern of cristae organization with wave-like contours. Gradual formation of mitochondrial ultrastructure occurs in naked mole rats for many years. Two mitochondrial populations are developed to the age of 5 years. In addition to the main population, there are some large organelles which exceed normal sizes by two to three times. Most cristae in these mitochondria are assembled into small groups, which form the curved and ring-like structures. The appearance of some specific structural changes (i.e. bundles of parallel cristae) is observed in the mitochondrial population of naked mole rat after 11 years of age. However, these bundles are very rare and of sporadic nature. Morphometric analysis has shown that the superficial density of the inner mitochondrial membrane is similar in all examined age groups of naked mole rats: 21.1 at 6 months; 23.21 at 3 years; 23.55 at 5 years; and 20.8 at 11 years. This level is almost two times lower than in other animals studied (mice and rats). The data demonstrate that pathological changes in mitochondrial apparatus are not present in naked mole rats at least until the age of 11 years. The mitochondrial apparatus corresponds to the phenotype in young animals, thus being another neotenic feature in naked mole rats. Full article

This paper begins with a refutation of the orthodox model of final Pleistocene human evolution, presenting an alternative, better supported account of this crucial phase. According to this version, the transition from robust to gracile humans during that period is attributable to selective breeding rather than natural selection, rendered possible by the exponential rise of culturally guided volitional choices. The rapid human neotenization coincides with the development of numerous somatic and neural detriments and pathologies. Uniformitarian reasoning based on ontogenic homology suggests that the cognitive abilities of hominins are consistently underrated in the unstable orthodoxies of Pleistocene archaeology. A scientifically guided review establishes developmental trajectories defining recent changes in the human genome and its expressions, which then form the basis of attempts to extrapolate from them into the future. It is suggested that continuing and perhaps accelerating unfavorable genetic changes to the human species, rather than existential threats such as massive disasters, pandemics, or astrophysical events, may become the ultimate peril of humanity. Full article

Several thousand Reticulitermes flavipes (Kollar) including worker, nymph, soldier, neotenic and alate castes were collected from three pine logs brought into the laboratory on dates five years apart. The neotenics, all nymphoid, were divided into three groups based on the extent of cuticle pigmentation and termed regular neotenics (RN), black-headed neotenics (BHN) or black neotenics (BN). All castes, from Log A, in 2008, provided a neutral sex ratio except BHN (N = 378) and BN (N = 51) which were exclusively male while the soldiers (N = 466) were female-biased. This information suggests that there is a sex-linked bifurcation along the path for termite development with a male-biased neotenic or female-biased soldier as the choice. In contrast, termites collected in 2004 from Log B provided sex ratios that included a female biased RN (N = 1017), a neutral soldier (N = 258) and male biased BHN (N = 99) and workers (N = 54). Log C, collected in 2009, provided female biased soldiers (N = 32), RNs (N = 18) and BHNs (N = 4) and only male BN (N = 5). Eight laboratory cultures, ranging in age from five to 14 years old, also were sampled and all castes sexed. The census included a 14-year old queen-right colony, an 8-year old polyandrous colony and six colonies provided nymphs and male-biased worker populations. Together these data indicate a flexible caste determination system providing a unique opportunity for a better understanding of the flexible developmental options available in R. flavipes that we discuss relative to the literature on Reticulitermes ontogeny. Full article

This paper addresses the development of the human species during a relatively short period in its evolutionary history, the last forty millennia of the Pleistocene. The hitherto dominant hypotheses of “modern” human origins, the replacement and various other “out of Africa” models, have recently been refuted by the findings of several disciplines, and by a more comprehensive review of the archaeological evidence. The complexity of the subject is reconsidered in the light of several relevant frames of reference, such as those provided by niche construction and gene-culture co-evolutionary theories, and particularly by the domestication hypothesis. The current cultural, genetic and paleoanthropological evidence is reviewed, as well as other germane factors, such as the role of neurodegenerative pathologies, the neotenization of humans in their most recent evolutionary history, and the question of cultural selection-based self-domestication. This comprehensive reassessment leads to a paradigmatic shift in the way recent human evolution needs to be viewed. This article explains fully how humans became what they are today. Full article